Determination of the mass fraction of fat in confectionery products. Confectionery products, methods for determining the mass fraction of fat. Extraction-weight method for determining the mass fraction of fat in flour confectionery products and finishing and baked semi-finished products
- Appendix 1 is mandatory. Correction for refractometric determination of the refractive indices of a fat solution and a mixture of fats in a solvent for temperatures from 15 to 35°C Appendix 2 is mandatory. Refractive indices and density of fats at 20°C Appendix 3 is mandatory. Correction for refractometric determination of the refractive index of fat and a mixture of fats for temperatures from 15 to 35 ° C. Appendix 4 is for reference. An example of calculating the refractive index and density of a mixture of fats in confectionery products. Recipe for "Kara-Kum" sweets
State standard of the USSR GOST 5899-85
"Confectionery products. Methods for determining the mass fraction of fat"
(approved by Decree of the USSR State Standard of August 30, 1985 N 2823)
Confectionery Methods for determination of fat fraction of total mass
Instead of GOST 5899 - 63
This standard applies to confectionery products and semi-finished products and establishes refractometric and extraction-gravity methods for determining the mass fraction of fat.
2. Refractometric method for determining the mass fraction of fat in confectionery products and semi-finished products (in chocolate and chocolate semi-finished products, pralines, cocoa powder, marzipan, flour confectionery products, finishing and baked semi-finished products, halva, etc.)
2.1. The method is based on extracting fat from a sample with monobromo- or monochloronaphthalene and determining the refractive index of the solvent and fat solution.
2.2. Equipment, materials and reagents
Hourglass at 1, 2, 3 minutes.
GOST 22524-77, capacity 25, 50.
GOST 12026-76.
GOST 9147-80 or evaporation bowl 1, 2 or 3 according to GOST 9147-80.
Conical flask with ground stopper in accordance with GOST 25336-82, nominal capacity 25, 50, 100.
Technical ethyl alcohol according to GOST 17299-78.
Ethyl ether (dehydrated) according to GOST 6265-74 or
2.3. Preparing for the test
2.3.1. Checking the refractometer zero point
Before starting to work with a refractometer, check the zero point of the device using distilled water. To do this, 1 - 2 drops of distilled water are placed between the prisms, then the scale eyepiece and the telescope eyepiece are adjusted to sharpness so that the field of view and sight lines are clearly visible.
The sighting line of the scale eyepiece is set to 1.333 (the refractive index of distilled water at 20°C) and the chiaroscuro boundary is observed through the telescope in relation to the intersection point of two mutually perpendicular sighting lines.
If the chiaroscuro boundary passes through the point of intersection of the sighting lines, then the device is set to zero. If this is not the case, then using a special key and screw, place the border of light and shadow at the point of intersection of the sighting lines.
The device must be checked at a prism temperature of 20°C. Temperature is measured with a thermometer specially mounted near the prisms of the refractometer. The required temperature is established by passing water at a given temperature.
2.3.2. Determination of the refractive index of a solvent
In each batch of monobromo- or monochloronaphthalene received for analysis, the refractive index is determined with an error of no more than 0.0001 by applying 1 - 2 drops of this solvent to the refractometer prism at a temperature ()°C.
2.3.3. Determination of solvent density
The pycnometer, dried at a temperature of 100 - 105 ° C to constant weight and cooled in a desiccator to room temperature, is weighed with an error of no more than 0.0015 g, and filled using a small funnel with distilled water slightly above the mark.
The pycnometer is closed with a stopper and kept for 20 minutes in a water thermostat or water bath at water temperature ()°C. At this temperature, the water level in the pycnometer is brought to the mark using a capillary tube or a strip of filter paper rolled into a tube. The pycnometer is again closed with a stopper and kept in a thermostat or water bath for another 10 minutes, checking the position of the meniscus in relation to the mark. Then the pycnometer is removed from the thermostat or water bath, wiped dry from the outside with a soft cloth, left under the glass of an analytical balance for 20 minutes and weighed with an error of no more than 0.0015 g.
Then it is freed from water, rinsed successively with ethyl alcohol and ether, dried as indicated above, cooled in a desiccator to room temperature and filled with the test solvent, after which the same operations are performed as with distilled water.
Filling the pycnometer with water (or solvent), installing the meniscus and weighing is repeated three times. The discrepancies between parallel weighings should not be more than 0.005 g. The arithmetic average is taken for calculation.
Solvent density () in is calculated using the formula
where m is the mass of the empty pycnometer, g;
Weight of pycnometer with distilled water, g;
Weight of pycnometer with solvent, g;
998.23 - value of water density at 20°C, .
2.3.3.1. The result of the determination is calculated accurate to the first decimal place. The final result is rounded to the nearest whole number.
2.3.4. Solvent Pipette Calibration
Calibration is carried out for each newly used pipette.
A pipette with a capacity of 2 is calibrated for the solvent, measuring with it the corresponding volume of monobromine or monochloronaphthalene and weighing it in a pre-weighed flask with a ground-in stopper or a weighing cup with an error of no more than 0.0015 g. The discrepancy between parallel weighings should be no more than 0.005 g. Weighing carried out three times. For the calculation, the arithmetic mean is taken.
The volume of the pipette () is calculated using the formula
where is the mass of the solvent corresponding to the volume of the pipette taken, g;
The density of the solvent at a temperature of 20°C, determined according to paragraph 2.3.3, .
2.3.4.1. The result is calculated accurate to the fourth decimal place. The final result is rounded to the third decimal place.
2.4. Carrying out the test
A sample of the crushed test product is weighed with an error of no more than 0.001 g.
The weight of the sample is determined from the table.
The sample is placed in a porcelain mortar or porcelain cup, rubbed with a pestle for 2 - 3 minutes, then 2 solvents are added with a pre-calibrated pipette according to clause 2.3.4 and again grind everything for 3 minutes, filter the contents through a paper filter into a small glass or other laboratory glassware . The filtrate is stirred with a glass rod. 2 drops of the filtrate are applied to the prism of a refractometer at a temperature of ()°C and the refractive index is measured.
The refractive index is determined at least three times and the arithmetic mean of the measurement results is taken as the test result.
To avoid evaporation of the solvent, the duration of filtration and determination of the refractive index should be no more than 30 minutes.
If the determination of the refractive index was not carried out at 20°C, then a correction must be made. If, when determining the refractive index, the temperature of the refractometer prisms is in the range of 15 - 20 ° C, the correction should be subtracted from the value of the refractive index; if the determination is carried out within the temperature range of 20 - 35 ° C, then the corresponding correction should be added to the found refractive index according to the mandatory Appendix 1.
2.5. Processing the results
2.5.1. The mass fraction of fat (X) as a percentage is calculated using the formula
where is the volume of solvent taken to extract fat, ;
Density of fat at 20°C, ;
Solvent refractive index;
Refractive index of a solution of fat in a solvent;
Refractive index of fat;
Weight of product sample, g.
2.5.2. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula
where W is the mass fraction of moisture in the product under study, %.
2.5.3. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place.
2.5.4. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between which in one laboratory should not exceed 0.3% in absolute value, and those performed in different laboratories - 0.5%.
The limit of possible measurement error is 0.5% (P=0.95).
Notes:
1. When calculating the mass fraction of fat, use the refractive index and density of fat given in the mandatory appendix 2.
2. If the product under study contains a mixture of fats (for example, cocoa butter and butter in chocolate with milk, nut butter, cocoa butter and confectionery fat in candy boxes, etc.), the refractive index and density can be determined by calculation (see .reference appendix 4).
The refractive index of a mixture of fats can also be determined by extracting fat from the test product as follows: 5 - 10 g of the crushed product is mixed with 15 - 20 ethyl or petroleum ether, chloroform or carbon tetrachloride, shaken for 10 minutes, the extract is filtered into a flask, the solvent is completely distilled off , the residue is dried in an oven at a temperature of 100 - 105 ° C for 30 minutes and the refractive index of the fat mixture is determined according to clause 2.4, taking into account the correction for temperature in accordance with the mandatory Appendix 3.
3. For unknown fats and mixtures of fats, the density is taken to be 930.
4. If the test product contains more than 5% water, then the mortar with the sample is placed in a drying cabinet and the sample is dried at a temperature of 100 - 105 ° C for 30 minutes, then the solvent is poured into the mortar, after it has cooled to room temperature, with a micropipette.
5. When the sample with the solvent is well ground in a mortar, when the mixture is transferred to the filter, it is allowed to apply drops of the fat solution in the solvent flowing from the funnel onto the prism of the refractometer, without waiting for the entire mixture to be filtered.
3. Refractometric method for determining the mass fraction of fat in confectionery products such as toffee, fudge, creamy toffee, START, KOROVKA candies, etc.
3.1. The method is based on the extraction of fat from a sample with monobrome or monochloronaphthalene after pre-treatment with acetic acid; The refractive index is determined after drying the extract with anhydrous sodium carbonate.
3.2. Equipment, materials and reagents
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g according to GOST 24104-80 or other scales that meet the specified requirements for their metrological characteristics.
A universal refractometer (URL) with a limiting refractive index of up to 1.7 or a refractometer of another system.
Electric drying cabinet with contact or technical thermostat.
Laboratory mercury glass thermometer according to GOST 215-73.
Hourglass at 1, 2, 3 minutes.
Water bath.
Pycnometer type PZh2 with a neck diameter of 6 mm according to GOST 22524-77, capacity 25, 50.
Pipettes version 1 or 4, 2nd accuracy class according to GOST 20292-74, capacity 2.
Laboratory filter paper according to GOST 12026-76.
Porcelain mortar with a diameter of no more than 70 mm with a pestle in accordance with GOST 9147-80 or evaporating bowl 1, 2, 3 in accordance with GOST 9147-80.
Solvent (monobromonaphthalene) with a refractive index of about 1.66 or (monochloronaphthalene) with a refractive index of about 1.63.
3.4. Carrying out the test
A sample of the crushed test product in an amount of about 1.5 g is weighed with an error of no more than 0.001 g and placed in a porcelain mortar or porcelain cup.
When determining the fat in toffee, add 1 water to the sample, for other products - 0.5 water. The sample is completely dissolved in a hot water bath, then cooled to room temperature, about 1 g of clean dry river sand and 1 acetic acid with a mass fraction of 80% are added, everything is thoroughly ground for 2 minutes, after which 2 monobromo- or monochloronaphthalene are added and ground for 3 minutes, add 2 g of anhydrous sodium carbonate when analyzing toffee (1 g for other products), mix thoroughly for about 1 minute and filter the contents through a paper filter into a small glass. The filtrate is stirred with a glass rod.
2 drops of the filtrate are applied to the prism of a refractometer at a temperature of ()°C and the refractive index is measured.
The refractive index is determined at least three times and the arithmetic mean of the measurement results is taken as the test result.
If the determination was not carried out at 20°C, then an amendment should be made according to clause 2.4 (see mandatory Appendix 1).
4. Extraction-weight method for determining the mass fraction of fat in flour confectionery products and finishing and baked semi-finished products
4.1. The method is based on extracting fat from a pre-hydrolyzed sample of the product with a solvent and determining the amount of fat by weighing after removing the solvent from a certain volume of the resulting solution.
4.2. Equipment, materials and reagents
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g and 3rd class with a maximum weighing limit of 1 kg according to GOST 24104-80 or other scales that meet the specified requirements for their metrological characteristics.
Electric drying cabinet with contact or technical thermostat.
Hourglass at 1, 2, 3 minutes.
Laboratory centrifuge.
Electric stove.
Water bath.
Flasks type Kn, version 1, 2 according to GOST 25336-82, with a capacity of 100, 250.
Refrigerator with a straight tube according to GOST 25336-82.
Medical hygroscopic cotton wool according to GOST 5556-81.
Laboratory filter paper according to GOST 12026-76.
Rubber bulb.
Phenolphthalein according to GOST 5850-72, alcohol solution with a mass fraction of 1%.
4.3. Testing
4.3.1. A sample of the crushed test product in the amount of 10 g (if the fat content in the products is over 10%, the sample can be reduced to 5 g) is weighed with an error of no more than 0.01 g, placed in a conical flask with a capacity of 250, poured 100 1.5% hydrochloric acid (or 100 5% sulfuric acid), boil in a flask with reflux over low heat for 30 minutes. Then the flask is cooled with water to room temperature, 50% chloroform is added, tightly closed with a well-fitting stopper, shaken vigorously for 15 minutes, the contents are poured into centrifuge tubes and centrifuged for 2 - 3 minutes. Three layers are formed in the test tube. The top aqueous layer is removed. Using a pipette equipped with a rubber bulb, select the chloroform fat solution and filter it into a dry flask through a small cotton swab inserted into the narrow part of the funnel, with the tip of the pipette touching the cotton wool. 20 filtrate is placed in a flask with a capacity of approximately 100, previously brought to a constant mass and weighed with an error of no more than 0.001 g.
Filtration and selection should be carried out within 2 minutes, the chloroform from the flask is distilled off in a hot bath using a refrigerator with a straight tube. The fat remaining in the flask is dried to a constant weight, usually 1 - 1.5 hours, at a temperature of 100 - 105 ° C, cooled in a desiccator for 20 minutes and the flask is weighed with an error of no more than 0.001 g.
4.3.2. The following delamination method is allowed. After hydrolysis, 5 ammonia solution (density 910.0), 50 chloroform are added to the cooled flask. The contents of the flask are shaken for 15 minutes and left to settle for 1 hour. During this time, the lower chloroform layer is completely separated and becomes clearly visible. If separation does not occur, add another 2-3 ammonia, making sure that the phenolphthalein reaction remains acidic.
After separation, selection, filtration, distillation of the chloroform layer and drying of the fat are carried out according to clause 4.3.1.
Notes:
1. Distillation and filtration of the solvent is carried out under a hood.
2. In the absence of chloroform, the use of dichloroethane is allowed, which should be stored in dark bottles.
4.4. Processing the results
4.4.1. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula
where is the mass of the flask with dried fat, g;
Mass of an empty flask, g;
50 - volume of chloroform taken to dissolve fat;
m is the mass of the sample, g;
20 - volume of chloroform solution of fat taken for distillation;
W is the mass fraction of moisture in the product under study, %.
4.4.2. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place.
4.4.3. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between them in absolute value should not exceed 0.5%. The limit of possible measurement error is 0.8% (P=0.95).
5. Extraction-weight method
5.1. The method is used when disagreements arise to determine the mass fraction of fat in all confectionery products and semi-finished products.
The method is based on the extraction of fat with a solvent directly from a sample or from a sample pre-treated with hydrochloric acid. After distilling off the solvent from the resulting extract, the residue is dried and weighed.
5.2. Equipment, materials and reagents
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g according to GOST 24104-80 or other scales that meet the specified requirements for their metrological characteristics.
Electric drying cabinet with contact or technical thermostat.
Electric stove.
Petroleum ether according to regulatory and technical documentation.
5.3. Preparing for the test
A sample of the crushed product is weighed with an error of no more than 0.001 g. The mass of the sample of 5 - 10 g is calculated depending on the mass fraction of fat in the product under study so that the sample contains about 1 - 2 g of fat.
Products with high humidity, which spread during grinding and form lumps (taffy, bird's milk candy bodies, toffee, etc.), after grinding are subjected to the following processing. 15-20 distilled water and 20 concentrated hydrochloric acid are poured into a weighed glass, the contents are mixed with a glass rod, the glass is covered with a watch glass, and the contents are heated in a boiling water bath for 5 minutes. Then the watch glass is rinsed with hot distilled water over the glass.
Prepare a funnel with a filter, moisten the filter with distilled water, transfer the contents of the glass to the filter, allow the liquid to drain and wash the residue on the filter at least four times with hot distilled water. When washing, the filter must be filled with water all the time, so it is filled with water immediately as soon as the previous portion of liquid has drained.
The washed filter is removed from the funnel, placed in a weighing bottle and dried in an oven at a temperature of 100 - 105°C to constant weight.
Confectionery products with low moisture content (chocolate, halva, cookies) may not be treated with hydrochloric acid.
5.4. Testing
A sample of the crushed product or a dried filter with a sample treated with acid is placed in a paper cartridge, at the bottom of which a piece of cotton wool is preliminarily placed and which is sealed so as to close the cracks at the bottom. The top of the cartridge is also tightly covered with cotton wool. The cartridge is placed in the extractor, a refrigerator and a receiving flask are attached to the extractor. The receiving flask is pre-dried to constant weight at a temperature of 100 - 105°C, cooled in a desiccator to room temperature and weighed with an error of no more than 0.001 g.
Having placed the cartridge in the Soxhlet extractor and assembled the entire device, add the solvent, rinsing it first with the bottle in which the filter with the sample was dried.
The amount of solvent should be 1.5 times the volume of the extractor when filling it to the upper elbow of the siphon.
Extraction is carried out for at least 5 hours from a sample not treated with acid, and for at least 3.5 hours from a sample treated with acid.
To determine the end of extraction, 1-2 liquids are taken from the extractor, applied to a dry watch glass, and the solvent is evaporated. If the glass is clear after the solvent evaporates, the extraction is complete.
Once the extraction is complete, the flask containing the extracted fat and solvent is allowed to cool. Disconnect the flask, refrigerator and extractor. The receiving flask is connected to a direct condenser and the solvent is distilled off. After this, the flask is placed in a boiling water bath and the remaining solvent is removed.
To completely remove the solvent and moisture, the flask with fat is placed in a drying cabinet and kept at a temperature of 100 - 105 ° C for 1 hour, then cooled in a desiccator and weighed with an error of no more than 0.001 g.
5.5. Processing the results
5.5.1. The mass fraction of fat () as a percentage is calculated using the formula
where is the mass of the receiving flask without fat, g;
Mass of the receiving flask with fat, g;
m is the mass of the sample, g.
5.5.2. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula
where W is the mass fraction of moisture in the product under study, %.
5.5.3. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place.
5.5.4. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between which in one laboratory should not exceed 0.3% in absolute value, and those performed in different laboratories - 0.5%.
The limit of possible values of measurement error is 0.5%, (P = 0.95).
6. Safety requirements
6.1. The solvents used - ethyl ether, chloroform (trichloromethane), ethylene chloride (dichloroethane) and carbon tetrachloride must comply with the safety requirements regulated by GOST 6265-74, GOST 20015-74, GOST 1942-86
GOST 5899-85
Group H49
INTERSTATE STANDARD
CONFECTIONERY PRODUCTS
Methods for determining the mass fraction of fat
Confectionery Methods for determination of fat fraction of total mass
MKS 67.180.10
OKSTU 9109
Date of introduction 1986-07-01
ENTERED INTO EFFECT by Resolution of the USSR State Committee on Standards dated August 30, 1985 N 2823
The validity period was lifted according to Protocol No. 5-94 of the Interstate Council for Standardization, Metrology and Certification (IUS 11-12-94)
INSTEAD GOST 5899-63
REISSUE
This standard applies to confectionery products and semi-finished products and establishes refractometric and extraction-gravity methods for determining the mass fraction of fat.
1. SAMPLING METHODS
1. SAMPLING METHODS
1.1. Sampling - according to GOST 5904-82.
2. REFRACTOMETRIC METHOD FOR DETERMINING THE MASS FRACTION OF FAT IN CONFECTIONERY PRODUCTS AND SEMI-FINISHED PRODUCTS
2.1. The method is based on extracting fat from a sample with monobromo- or monochloronaphthalene and determining the refractive index of the solvent and fat solution.
2.2. Equipment, materials and reagents
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g according to GOST 24104-88* or other scales that meet the specified requirements for their metrological characteristics.
_________________
* On July 1, 2002, GOST 24104-2001 came into force (hereinafter).
Hourglass at 1, 2, 3 minutes.
Desiccator according to GOST 25336-82.
Porcelain mortar with a diameter of no more than 70 mm with a pestle in accordance with GOST 9147-80 or evaporating bowl 1, 2 or 3 in accordance with GOST 9147-80.
Conical flask with ground stopper in accordance with GOST 25336-82, nominal capacity 25, 50, 100 cm.
Technical ethyl alcohol according to GOST 17299-78.
Ethyl ether (dehydrated).
2.3. Preparing for the test
2.3.1. Checking the refractometer zero point
Before starting to work with a refractometer, check the zero point of the device using distilled water. To do this, 1-2 drops of distilled water are placed between the prisms, then the scale eyepiece and the telescope eyepiece are adjusted to sharpness so that the field of view and sight lines are clearly visible.
The sighting line of the scale eyepiece is set to 1.333 (the refractive index of distilled water at 20 °C) and the chiaroscuro boundary is observed through the telescope in relation to the intersection point of two mutually perpendicular sighting lines.
If the chiaroscuro boundary passes through the point of intersection of the sighting lines, then the device is set to zero. If this is not the case, then using a special key and screw, place the border of light and shadow at the point of intersection of the sighting lines.
The device must be checked at a prism temperature of 20 °C. Temperature is measured with a thermometer specially mounted near the prisms of the refractometer. The required temperature is established by passing water at a given temperature.
2.3.2. Determination of the refractive index of a solvent
In each batch of monobromo- or monochloronaphthalene received for analysis, the refractive index is determined with an error of no more than 0.0001 by applying 1-2 drops of this solvent to the refractometer prism at a temperature of (20.0±0.1) °C.
2.3.3. Determination of solvent density
The pycnometer, dried at a temperature of 100 ° C - 105 ° C to constant weight and cooled in a desiccator to room temperature, is weighed with an error of no more than 0.0015 g and filled using a small funnel with distilled water slightly above the mark.
The pycnometer is closed with a stopper and kept for 20 minutes in a water thermostat or water bath at a water temperature of (20.0±0.1) °C. At this temperature, the water level in the pycnometer is brought to the mark using a capillary tube or a strip of filter paper rolled into a tube. The pycnometer is again closed with a stopper and kept in a thermostat or water bath for another 10 minutes, checking the position of the meniscus in relation to the mark. Then the pycnometer is removed from the thermostat or water bath, wiped dry from the outside with a soft cloth, left under the glass of an analytical balance for 20 minutes and weighed with an error of no more than 0.0015 g.
Then it is freed from water, rinsed successively with ethyl alcohol and ether, dried as indicated above, cooled in a desiccator to room temperature and filled with the test solvent, after which the same operations are performed as with distilled water.
Filling the pycnometer with water (or solvent), installing the meniscus and weighing is repeated three times. The discrepancies between parallel weighings should not be more than 0.005 g. The arithmetic average is taken for calculation.
Solvent density () in kg/m is calculated using the formula
where is the mass of the empty pycnometer, g;
- mass of the pycnometer with distilled water, g;
- mass of pycnometer with solvent, g;
998.23 - value of water density at 20 °C, kg/m.
2.3.3.1. The result of the determination is calculated accurate to the first decimal place. The final result is rounded to the nearest whole number.
2.3.4. Solvent Pipette Calibration
Calibration is carried out for each newly used pipette.
A pipette with a capacity of 2 cm is calibrated by the solvent, measuring with it the corresponding volume of monobromine or monochloronaphthalene and weighing it in a pre-weighed flask with a ground stopper or a weighing cup with an error of no more than 0.0015 g. The discrepancy between parallel weighings should be no more than 0.005 g. Weighing is carried out three times. For the calculation, the arithmetic mean is taken.
The volume of the pipette () in cm is calculated using the formula
where is the mass of the solvent corresponding to the volume of the pipette taken, g;
- density of the solvent at a temperature of 20 °C, determined according to clause 2.3.3, kg/m.
2.3.4.1. The result is calculated accurate to the fourth decimal place. The final result is rounded to the third decimal place.
2.4. Carrying out the test
A sample of the crushed test product is weighed with an error of no more than 0.001 g.
The weight of the sample is determined from the table.
The sample is placed in a porcelain mortar or porcelain cup, ground with a pestle for 2-3 minutes, then 2 cm of solvent is added with a pre-calibrated pipette according to clause 2.3.4 and the whole thing is ground again for 3 minutes, the contents are filtered through a paper filter into a small glass or other laboratory dishes The filtrate is stirred with a glass rod. 2 drops of the filtrate are applied to the prism of a refractometer at a temperature of (20.0±0.1) °C and the refractive index is measured.
The refractive index is determined at least three times and the arithmetic mean value of the measurement results is taken as the test result.
To avoid evaporation of the solvent, the duration of filtration and determination of the refractive index should be no more than 30 minutes.
If the determination of the refractive index was not carried out at 20 °C, then a correction must be made. If, when determining the refractive index, the temperature of the refractometer prisms is within the range of 15 °C - 20 °C, the correction should be subtracted from the value of the refractive index; if the determination is carried out within the temperature range of 20 °C - 35 °C, then the correction should be added to the found refractive index the corresponding amendment in accordance with Appendix 1.
2.5. Processing the results
2.5.1. The mass fraction of fat () as a percentage is calculated using the formula
where is the volume of solvent taken to extract fat, cm;
- fat density at 20 °C, kg/m;
- refractive index of the solvent;
- refractive index of a fat solution in a solvent;
- refractive index of fat;
- weight of the product sample,
2.5.2. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula
where is the mass fraction of moisture in the product under study, %.
2.5.3. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place.
2.5.4. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between which in one laboratory should not exceed 0.3% in absolute value, and those performed in different laboratories - 0.5%.
Notes:
1. When calculating the mass fraction of fat, use the refractive indices and density of fats given in Appendix 2.
2. If the product under study contains a mixture of fats (for example, cocoa butter and butter in chocolate with milk, nut butter, cocoa butter and confectionery fat in candy boxes, etc.), the refractive index and density can be determined by calculation (see Appendix 4).
The refractive index of a mixture of fats can also be determined by extracting fat from the test product as follows: 5-10 g of the crushed product is mixed with 15-20 cm of ethyl or petroleum ether, chloroform or carbon tetrachloride, shaken for 10 minutes, the extract is filtered into a flask, the solvent is completely distilled off, the residue is dried in an oven at a temperature of 100-105 ° C for 30 minutes and the refractive index of the fat mixture is determined according to clause 2.4, taking into account the correction for temperature according to Appendix 3.
3. For unknown fats and mixtures of fats, the density is taken to be 930 kg/m.
4. If the test product contains more than 5% water, then the mortar with the sample is placed in a drying cabinet and the sample is dried at a temperature of 100 ° C - 105 ° C for 30 minutes, then the solvent is poured into the mortar, after it has cooled to room temperature, with a micropipette .
5. When the sample with the solvent is well ground in a mortar, when the mixture is transferred to the filter, it is allowed to apply drops of the fat solution in the solvent flowing from the funnel onto the prism of the refractometer, without waiting for the entire mixture to be filtered.
3. REFRACTOMETRIC METHOD FOR DETERMINING THE MASS PERCENTAGE OF FAT IN CONFECTIONERY PRODUCTS TYPE TOFFISH, CREAM FANDE, CANDIES “START”, “KOROKA”, etc.
3.1. The method is based on the extraction of fat from a sample with monobrome or monochloronaphthalene after pre-treatment with acetic acid; The refractive index is determined after drying the extract with anhydrous sodium carbonate.
3.2. Equipment, materials and reagents
A universal refractometer (URL) with a limiting refractive index of up to 1.7 or a refractometer of another system.
Electric drying cabinet with contact or technical thermostat.
Laboratory mercury glass thermometer in accordance with GOST 28498-90 and normative and technical documentation.
Hourglass at 1, 2, 3 minutes.
Water bath.
Desiccator according to GOST 25336-82.
Pycnometer type PZh2 with a neck diameter of 6 mm in accordance with GOST 22524-77, capacity 25, 50 cm.
Pipettes version 1 or 4, 2nd accuracy class according to GOST 29169-91, capacity 2 cm.
Glass glasses according to GOST 25336-82, capacity 25, 50 cm.
Glass funnels with a diameter of no more than 40 mm in accordance with GOST 25336-82.
Laboratory filter paper according to GOST 12026-76.
Porcelain mortar with a diameter of no more than 70 mm with a pestle in accordance with GOST 9147-80 or evaporating bowl 1, 2, 3 in accordance with GOST 9147-80.
The solvent is bromonaphthalene (monobromonaphthalene) with a refractive index of about 1.66 or -chloronaphthalene (monochloronaphthalene) with a refractive index of about 1.63.
Acetic acid according to GOST 61-75, chemically pure, solution with a mass fraction of 80%.
Anhydrous sodium carbonate according to GOST 83-79, chemical grade.
3.3. Preparing for the test
3.3.1. Checking the refractometer according to clause 2.3.1.
3.3.2. Determination of the refractive index of the solvent according to clause 2.3.2.
3.3.3. Determination of solvent density according to clause 2.3.3.
3.3.4. Calibration of the pipette according to the solvent according to clause 2.3.4.
3.4. Carrying out the test
A sample of the crushed test product in an amount of about 1.5 g is weighed with an error of no more than 0.001 g and placed in a porcelain mortar or porcelain cup.
When determining the fat in iris, add 1 cm of water to the sample, for other products - 0.5 cm of water. The sample is completely dissolved in a hot water bath, then cooled to room temperature, about 1 g of clean dry river sand and 1 cm of acetic acid with a mass fraction of 80% are added, everything is thoroughly ground for 2 minutes, after which 2 cm of monobromo or monochloronaphthalene is added and grind for 3 minutes, add 2 g of anhydrous sodium carbonate when analyzing iris (1 g for other products), mix thoroughly for about 1 minute and filter the contents through a paper filter into a small glass. The filtrate is stirred with a glass rod.
2 drops of the filtrate are applied to the prism of a refractometer at a temperature of (20.0±0.1) °C and the refractive index is measured.
The refractive index is determined at least three times and the arithmetic mean of the measurement results is taken as the test result.
If the determination was not carried out at 20 °C, then an amendment should be made according to clause 2.4 (see Appendix 1).
3.5. Processing the results
The results are processed according to clause 2.5 of section 2.
4. EXTRACTION-GRAVE METHOD FOR DETERMINING THE MASS FRACTION OF FAT IN FLOUR CONFECTIONERY PRODUCTS AND FINISHING AND BAKED SEMI-FINISHED PRODUCTS
4.1. The method is based on extracting fat from a pre-hydrolyzed sample of the product with a solvent and determining the amount of fat by weighing after removing the solvent from a certain volume of the resulting solution.
4.2. Equipment, materials and reagents
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g and 3rd class with a maximum weighing limit of 1 kg according to GOST 24104-88 or other scales that meet the specified requirements for their metrological characteristics.
Electric drying cabinet with contact or technical thermostat.
Hourglass at 1, 2, 3 minutes.
Laboratory centrifuge.
Electric stove.
Desiccator according to GOST 25336-82.
Water bath.
Flasks type Kn, version 1, 2 according to GOST 25336-82, capacity 100, 250 cm.
Cylinders of execution 1, 3 according to GOST 1770-74, capacity 100 cm.
Pipettes version 2, 2nd accuracy class, according to GOST 29169-91, capacity 20, 50 cm.
Ball refrigerator according to GOST 25336-82.
Refrigerator with a straight tube according to GOST 25336-82.
Glass glasses according to GOST 25336-82, capacity 25, 50 cm.
Glass funnels according to GOST 25336-82.
Laboratory filter paper according to GOST 12026-76.
Rubber bulb.
Hydrochloric acid according to GOST 3118-77, solution with a mass fraction of 1.5%, chemical grade.
Sulfuric acid according to GOST 4204-77, solution with a mass fraction of 5%, chemical grade.
Chloroform (trichloromethane) according to GOST 20015-88 or
Ethylene chloride (dichloroethane) according to GOST 1942-86 with a density of 1252.0-1253.5 kg/m.
Ammonia water according to GOST 3760-79.
Phenolphthalein according to NTD, alcohol solution with a mass fraction of 1%.
4.3. Testing
4.3.1. A sample of the crushed test product in the amount of 10 g (if the fat content in the products is over 10%, the sample can be reduced to 5 g) is weighed with an error of no more than 0.01 g, placed in a conical flask with a capacity of 250 cm3, 100 cm3 of 1.5% is added. hydrochloric acid (or 100 cm of 5% sulfuric acid), boil in a flask with reflux over low heat for 30 minutes. Then the flask is cooled with water to room temperature, 50 cm of chloroform is added, tightly closed with a well-fitting stopper, shaken vigorously for 15 minutes, the contents are poured into centrifuge tubes and centrifuged for 2-3 minutes. Three layers are formed in the test tube. The top aqueous layer is removed. Using a pipette equipped with a rubber bulb, take a chloroform solution of fat and filter it into a dry flask through a small cotton swab inserted into the narrow part of the funnel, with the tip of the pipette touching the cotton wool. 20 cm of the filtrate is placed in a flask with a capacity of approximately 100 cm, previously brought to a constant mass and weighed with an error of no more than 0.001 g.
Filtration and selection should be carried out within 2 minutes, the chloroform from the flask is distilled off in a hot bath using a refrigerator with a straight tube. The fat remaining in the flask is dried to a constant weight, usually 1-1.5 hours, at a temperature of 100 ° C - 105 ° C, cooled in a desiccator for 20 minutes and the flask is weighed with an error of no more than 0.001 g.
4.3.2. The following delamination method is allowed. After hydrolysis, 5 cm of ammonia solution (density 910.0 kg/m) and 50 cm of chloroform are added to the cooled flask. The contents of the flask are shaken for 15 minutes and left to settle for 1 hour. During this time, the lower chloroform layer is completely separated and becomes clearly visible. If separation does not occur, add another 2-3 cm of ammonia, making sure that the phenolphthalein reaction remains acidic.
After separation, selection, filtration, distillation of the chloroform layer and drying of the fat are carried out according to clause 4.3.1.
Notes:
1. Distillation and filtration of the solvent is carried out under a hood.
2. In the absence of chloroform, the use of dichloroethane is allowed, which should be stored in dark bottles.
4.4. Processing the results
4.4.1. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula
where is the mass of the flask with dried fat, g;
- mass of the empty flask, g;
50 - volume of chloroform taken to dissolve fat, cm;
- weight of the sample, g;
20 - volume of chloroform solution of fat taken for distillation, cm;
- mass fraction of moisture in the product under study, %.
4.4.2. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place.
4.4.3. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between them in absolute value should not exceed 0.5%. The limit of possible measurement error is 0.8% (0.95).
5. EXTRACTION-GRAVE METHOD
5.1. The method is used when disagreements arise to determine the mass fraction of fat in all confectionery products and semi-finished products.
The method is based on the extraction of fat with a solvent directly from a sample or from a sample pre-treated with hydrochloric acid. After distilling off the solvent from the resulting extract, the residue is dried and weighed.
5.2. Equipment, materials and reagents
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g according to GOST 24104-88 or other scales that meet the specified requirements for their metrological characteristics.
Electric drying cabinet with contact or technical thermostat.
Electric stove.
Desiccator according to GOST 25336-82.
Water bath.
Soxhlet device.
Medical hygroscopic cotton wool according to GOST 5556-81.
Laboratory filter paper according to GOST 12026-76.
Glass glasses according to GOST 25336-82, capacity 100, 150 cm.
Weighing cups (bugs) in accordance with GOST 25336-82.
Laboratory funnels with a diameter of 50-70 mm according to GOST 25336-82.
Cylinder version 1 according to GOST 1770-74, capacity 25 cm.
Porcelain mortar with a diameter of 110-180 mm with a pestle in accordance with GOST 9147-80.
Watch glass.
Hydrochloric acid according to GOST 3118-77, concentrated, chemical grade.
Carbon tetrachloride according to GOST 20288-74 or
Chloroform according to GOST 20015-88, or
Ethyl ether (dehydrated) or
Petroleum ether according to regulatory and technical documentation.
Distilled water according to GOST 6709-72.
5.3. Preparing for the test
A sample of the crushed product is weighed with an error of no more than 0.001 g. The mass of a sample of 5-10 g is calculated depending on the mass fraction of fat in the product under study so that the sample contains about 1-2 g of fat.
Products with high humidity, which spread during grinding and form lumps (taffy, bird's milk candy bodies, toffee, etc.), after grinding are subjected to the following processing. 15-20 cm of distilled water and 20 cm of concentrated hydrochloric acid are poured into a weighed glass, the contents are mixed with a glass rod, the glass is covered with a watch glass, and the contents are heated in a boiling water bath for 5 minutes. Then the watch glass is rinsed with hot distilled water over the glass.
Prepare a funnel with a filter, moisten the filter with distilled water, transfer the contents of the glass to the filter, allow the liquid to drain and wash the residue on the filter at least four times with hot distilled water. When washing, the filter must be filled with water all the time, so it is filled with water immediately as soon as the previous portion of liquid has drained.
The washed filter is removed from the funnel, placed in a weighing bottle and dried in an oven at a temperature of 100 ° C - 105 ° C until constant weight.
Confectionery products with low moisture content (chocolate, halva, cookies) may not be treated with hydrochloric acid.
5.4. Testing
A sample of the crushed product or a dried filter with a sample treated with acid is placed in a paper cartridge, at the bottom of which a piece of cotton wool is preliminarily placed and which is sealed so as to close the cracks at the bottom. The top of the cartridge is also tightly covered with cotton wool. The cartridge is placed in the extractor, a refrigerator and a receiving flask are attached to the extractor. The receiving flask is pre-dried to constant weight at a temperature of 100 °C - 105 °C, cooled in a desiccator to room temperature and weighed with an error of no more than 0.001 g.
Having placed the cartridge in the Soxhlet extractor and assembled the entire device, add the solvent, rinsing it first with the bottle in which the filter with the sample was dried.
The amount of solvent should be 1.5 times the volume of the extractor when filling it to the upper elbow of the siphon.
Extraction is carried out for at least 5 hours from a sample not treated with acid, and for at least 3.5 hours from a sample treated with acid.
To determine the end of extraction, 1-2 cm of liquid is taken from the extractor, applied to a dry watch glass, and the solvent is evaporated. If the glass is clear after the solvent evaporates, the extraction is complete.
Once the extraction is complete, the flask containing the extracted fat and solvent is allowed to cool. Disconnect the flask, refrigerator and extractor. The receiving flask is connected to a direct condenser and the solvent is distilled off. After this, the flask is placed in a boiling water bath and the remaining solvent is removed.
To completely remove the solvent and moisture, the flask with fat is placed in a drying cabinet and kept at a temperature of 100 ° C - 105 ° C for 1 hour, then cooled in a desiccator and weighed with an error of no more than 0.001 g.
5.5. Processing the results
5.5.1. The mass fraction of fat () as a percentage is calculated using the formula
where is the mass of the receiving flask without fat, g;
- mass of the receiving flask with fat, g;
- weight of the sample, g;
5.5.2. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula
where is the mass fraction of moisture in the product under study, %.
5.5.3. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place.
5.5.4. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between which in one laboratory should not exceed 0.3% in absolute value, and those performed in different laboratories - 0.5%.
The limit of possible measurement error is 0.5% (0.95).
6. SAFETY REQUIREMENTS
6.1. The solvents used - ethyl ether, chloroform (trichloromethane), ethylene chloride (dichloroethane) and carbon tetrachloride must comply with the safety requirements regulated by regulatory and technical documentation, GOST 20015-88, GOST 1942-86, GOST 20288-74.
6.2. Work with all solvents must be carried out only under traction.
6.3. When working with solvents, do not use open flame.
APPENDIX 1 (mandatory). Correction for refractometric determination of the refractive indices of a solution of fat and a mixture of fats in a solvent for temperatures from 15 to 35 ° C
ANNEX 1
Mandatory
Temperature, °C | Amendment |
APPENDIX 2 (mandatory). Refractive indices and density of fats at 20 °C
APPENDIX 2
Mandatory
Name of fats | Density, kg/m | Refractive index |
Cocoa butter | ||
Confectionery fat | ||
Margarine | ||
Soybean oil | ||
Sunflower oil | ||
Cow butter | ||
Corn oil | ||
Coconut oil | ||
Sesame oil | ||
Shocklin type fats | ||
Phosphatide concentrates | ||
Cooking fat | ||
Nut oil: | ||
peanuts | ||
almonds | ||
hazelnuts | ||
Apricot kernel oil | ||
Rendered pork fat |
APPENDIX 3 (mandatory). Correction for refractometric determination of the refractive index of fat and a mixture of fats for temperatures from 15 to 35 ° C
APPENDIX 3
Mandatory
Temperature, °C | Amendment |
|
Subtract from the found refractive index |
||
Add to the found refractive index |
||
APPENDIX 4 (for reference). An example of calculating the refractive index and density of a mixture of fats in confectionery products.
APPENDIX 4
Information
An example of calculating the refractive index and density of a mixture of fats
in confectionery products. Recipe for "Kara-Kum" sweets
name of raw materials | Mass fraction of dry substances, % | Total consumption of raw materials per 1 ton of unwrapped sweets, kg | Mass fraction of fat | Refractive index of fat | Fat density at | ||||
in dry matter | |||||||||
Chocolate glaze | |||||||||
Granulated sugar | |||||||||
Powdered sugar | |||||||||
Roasted almond kernel | |||||||||
Cocoa liquor | |||||||||
Butter | |||||||||
Cacao butter | |||||||||
Vanillin | |||||||||
Liquefier | |||||||||
To calculate the refractive index of a mixture of fats, the resulting sum of the products of fat masses and the refractive index (column 8) should be attributed to the sum of fat masses (column 6)
To calculate the density of a fat mixture, the resulting sum of the products of fat masses and fat density (column 10) should be attributed to the sum of fat masses (column 6)
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INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
INTERSTATE
STANDARD
CONFECTIONERY PRODUCTS Methods for determining the mass fraction of fat
Official publication
Standardinform
Preface
The goals, basic principles and basic procedure for carrying out work on interstate standardization are established by GOST 1.0-92 “Interstate standardization system. Basic provisions" and GOST 1.2-2009 "Interstate standardization system. Standards
Standard information
1 PREPARED by the State Scientific Institution “Research Institute of the Confectionery Industry” of the Russian Academy of Agricultural Sciences (GNU NII KP Rosselkhozakademii)
2 INTRODUCED by the Federal Agency for Technical Regulation and Metrology (Rosstandart)
3 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (protocol dated December 3, 2012 No. 54-P)
|
4 By Order of the Federal Agency for Technical Regulation and Metrology dated June 27, 2013 No. 256-st, the interstate standard GOST 31902-2012 was put into effect as a national standard of the Russian Federation on January 1, 2014.
5 This standard has been prepared based on the application of GOST R 54053-2010
6 INTRODUCED FOR THE FIRST TIME
Information about changes to this standard is published in the annual information index “National Standards”, and the text of changes and amendments is published in the monthly information index “National Standards”. In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the monthly information index “National Standards”. Relevant information, notifications and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet
©Standardinform, 2014
In the Russian Federation, this standard cannot be fully or partially reproduced, replicated and distributed as an official publication without permission from the Federal Agency for Technical Regulation and Metrology
Laboratory filter paper according to GOST 12026.
A porcelain mortar with a diameter of no more than 70 mm with a pestle in accordance with GOST 9147 or an evaporating bowl 1,2 or 3 in accordance with GOST 9147.
The solvent is a-bromonaphthalene (monobromonaphthalene; 1-bromonaphthalene reactive) with a refractive index of about 1.66 or a-chloronaphthalene (monochloro-naphthalene) with a refractive index of about 1.63.
Technical ethyl alcohol (hydrolysis) in accordance with GOST 17299 or rectified technical ethyl alcohol in accordance with GOST 18300.
9.3 Preparing to take measurements 9.3.1 Checking the refractometer zero point
Before starting to work with a refractometer, check the zero point of the device using distilled water. To do this, 1-2 drops of distilled water at a temperature of (20.0 ± 0.1) °C are placed between the prisms, then the scale eyepiece and the telescope eyepiece are set to sharpness so that the field of view and sight lines are clearly visible.
The sighting line of the scale eyepiece is set to 1.333 (the refractive index of distilled water at a temperature of 20 °C) and the chiaroscuro boundary is observed through the telescope in relation to the intersection point of two mutually perpendicular sighting lines.
If the chiaroscuro boundary passes through the point of intersection of the sighting lines, then the device is set to zero. If this is not the case, then using a special key and screw, set the border of light and shadow to the point of intersection of the sighting lines.
The device must be checked at a prism temperature of 20 °C. Temperature is measured with a thermometer specially mounted near the prisms of the refractometer. The temperature of the prism is ensured by water passing through it at a temperature of 20 °C.
9.3.2 Determination of the refractive index of a solvent
In each batch of monobromo- or monochloronaphthalene received for analysis, the refractive index is determined with an error of no more than 0.0001 by applying one or two drops of this solvent to the refractometer prism at a temperature of (20.0 + 0.1) °C.
9.3.3 Determination of solvent density
The pycnometer, dried at a temperature of 100 °C-105 °C to a constant weight and cooled in a desiccator to a temperature of (20.0 + 0.1) °C, is weighed with an error of no more than 0.0015 g, filled using a small funnel with distilled water a little higher tags.
The pycnometer is closed with a stopper and kept for 20 minutes in a water thermostat or water bath at a water temperature of (20.0 + 0.1) °C. At this temperature, the water level in the pycnometer is brought to the mark using a capillary tube or a strip of filter paper rolled into a tube. The pycnometer is again closed with a stopper and kept in a thermostat or water bath for another 10 minutes, checking the position of the meniscus in relation to the mark. Then the pycnometer is removed from the thermostat or water bath, the outside is wiped dry with a soft cloth, left in the case of the analytical balance for 20 minutes and weighed with an error of no more than 0.0015 g.
Then it is freed from water, rinsed successively with ethyl alcohol and ether, dried as indicated above, cooled in a desiccator to room temperature and filled with a solvent, after which the same operations are carried out as with distilled water.
Filling the pycnometer with water (or solvent), installing the meniscus and weighing is repeated three times. The discrepancies between parallel weighings should not be more than 0.005 g. The arithmetic mean is taken for calculation.
Solvent density p 20, kg/m 3, calculated by the formula
20 = (t 2 -t)-99823^ (5)
where t 2 is the mass of the pycnometer with solvent, g; t is the mass of the empty pycnometer, g;
GOST 31902-2012
998.23 - value of water density at a temperature of 20 °C, kg/m3; t 1 - mass of pycnometer with distilled water, g.
Solvent density is calculated to the third decimal place and rounded to the second decimal place.
9.3.4 Solvent pipette calibration
Calibration is carried out for each newly used pipette.
A pipette with a capacity of 2 cm 3 is calibrated by the solvent, measuring with it the corresponding volume of monobromine or monochloronaphthalene and weighing it in a pre-weighed flask with a ground stopper or a weighing cup with an error of no more than 0.0015 g. The discrepancy between parallel weighings should be no more than 0.005 g Weighing is carried out three times. For the calculation, the arithmetic mean is taken.
Pipette capacity V p, cm 3, is calculated using the formula
where is the mass of the solvent corresponding to the capacity of the pipette taken, g;
p*° - density of the solvent at a temperature of 20 °C, determined according to 9.3.3, kg/m 3.
9.3.4.1 The result is calculated to the fourth decimal place. The final result is rounded to the third decimal place.
9.4 Taking measurements
A sample of the crushed analyzed product is weighed with an error of no more than 0.001 g. The mass of the analyzed sample is determined according to Table 3.
A sample of the product is placed in a porcelain mortar or porcelain cup, ground with a pestle for 2-3 minutes, then 2 cm 3 of solvent is added with a pre-calibrated pipette according to 9.3.4 and the whole thing is ground again for 3 minutes, filter the contents through a paper filter into a small glass or other laboratory dishes The filtrate is stirred with a glass rod.
Two drops of the filtrate are applied to the prism of a refractometer at a temperature of (20.0 ± 0.1) °C and the refractive index is read.
The refractive index is determined at least three times and the arithmetic mean value of the measurement results is taken as the result of the determination.
To avoid evaporation of the solvent, the duration of filtration and determination of the refractive index should not exceed 30 minutes.
If the determination of the refractive index was not carried out at a temperature of 20 °C, then a correction is made. If, when determining the refractive index, the temperature of the refractometer prisms is 15 °C-20 °C, then the correction should be subtracted from the refractive index value; if the determination is carried out at a temperature of 20 °C-35 °C, then the corresponding correction should be added to the found refractive index according to Appendix A.
9.5 Processing of measurement results
9.5.1 Mass fraction of fatХ,%, is calculated using the formula
at r Rz° Lr-/7r. f iqq t-1000 P rzh -P f
where \/ p is the volume of solvent taken to extract fat, cm 3; p*° - fat density at 20 °C, kg/m3;
t is the mass of the analyzed sample, g;
Г7 р - refractive index of the solvent;
PrZh - refractive index of a fat solution in a solvent;
Rf - refractive index of fat.
9.5.2 Mass fraction of fat X-,% in terms of dry matter, is calculated using the formula
X 1 = X "100 (8)
where X is the mass fraction of fat, %;
W is the mass fraction of moisture in the analyzed product according to GOST 5900, %.
9.5.3 Calculations are carried out to the second decimal place, followed by rounding to the first decimal place.
The final result of determining the mass fraction of fat in confectionery products and semi-finished products is taken to be the arithmetic mean of the results of two parallel determinations performed under repeatability conditions, if the acceptance condition is met
I Yi-Y 2\ where Y 1 and Y 2 are the results of two parallel determinations, %; g - repeatability (convergence) limit of two parallel determinations, %, given in Table 4. 9.5.4 Characteristics of the error in determining the mass fraction of fat in confectionery products and semi-finished products with a confidence probability of P = 0.95 are given in Table 4. Notes 1 When calculating the mass fraction of fat, the refractive indices and density of fats given in Appendix B are used. 2 If the analyzed product contains a mixture of fats (for example, cocoa butter in chocolate with milk, nut butter, cocoa butter and confectionery fat in candy cases, etc.), the refractive index and density can be determined by calculation (see Appendix D) . The refractive index of a mixture of fats can also be determined by extracting fat from the analyzed product as follows: 5-10 g of the crushed product is mixed with 15-20 cm 3 of ethyl or petroleum ether, chloroform or carbon tetrachloride, shaken for 10 minutes, the extract is filtered into a flask , the solvent is completely distilled off, the residue is dried in an oven at a temperature of 105 ° C for 30 minutes and the refractive index of the fat mixture is determined according to 9.4, taking into account the correction for temperature according to Appendix B. 3 For unknown fats and mixtures of fats, the density is taken to be 930 kg/m 3 . 4 If the analyzed product contains more than 5% water, then the mortar with the analyzed sample is placed in a drying cabinet and the sample is dried at a temperature of 100 ° C-105 ° C for 30 minutes, then the solvent is poured into the mortar, after it has cooled to room temperature, with a micropipette. 5 If the sample is well ground with the solvent in a mortar, when the mixture is transferred to the filter, it is allowed to apply drops of the fat solution in the solvent flowing from the funnel onto the prism of the refractometer, without waiting for the entire mixture to be filtered. The method is based on the extraction of fat from the analyzed sample with monobromine or monochloronaphthalene after pre-treatment with acetic acid. The refractive index is determined after drying the extract with anhydrous sodium carbonate. Sodium carbonate anhydrous x. parts according to GOST 83. The river sand is clean. It is allowed to use other measuring instruments and auxiliary equipment with metrological and technical characteristics and reagents of quality not lower than those specified. 763 cm3 of concentrated acetic acid with a density of 1.049 g/cm3 is placed in a volumetric flask with a capacity of 1000 cm3. The volume of the solution is adjusted to the mark with distilled water. 10.4.1 Checking the refractometer - according to 9.3.1. 10.4.2 Determination of the refractive index of the solvent - according to 9.3.2. 10.4.3 Determination of solvent density - according to 9.3.3. 10.4.4 Calibration of the pipette for solvent - according to 9.3.4. The analyzed sample of the crushed product in an amount of about 1.5 g is weighed with an error of no more than 0.001 g and placed in a porcelain mortar or porcelain cup. When determining fat in confectionery products with a moisture mass fraction of no more than 9% (such as toffee), add 1 cm 3 of water to the sample; for confectionery products with a moisture mass fraction of at least 9% (such as milk mass candies) - 0.5 cm 3 water. The analyzed sample is completely dissolved in a hot water bath, then cooled to room temperature, about 1 g of clean dry river sand and 1 cm 3 of acetic acid with a mass fraction of 80% are added, everything is thoroughly ground for 2 minutes, after which 2 cm 3 of monobrome is added - or monochloronaphthalene and grind for 3 minutes. If the mass fraction of moisture in the confectionery product is no more than 9%, add 2 g of anhydrous sodium carbonate, and no less than 9% - 1 g; mix thoroughly for about 1 minute and filter the contents through a paper filter into a small glass. The filtrate is stirred with a glass rod. Two drops of the filtrate are applied to the prism of a refractometer at a temperature of (20.0 + 0.1) °C and the refractive index is determined. The refractive index is determined at least three times and the arithmetic mean value of the measurement results is taken as the result of the determination. If the determination was not carried out at a temperature of 20 °C, then the amendment should be made according to 9.4 (see Appendix A). 10.6.1 Results are processed according to 9.5. 10.6.2 The final result of determining the mass fraction of fat in confectionery products containing milk and products of its processing is taken as the arithmetic mean value of the results of two parallel determinations performed under repeatability conditions, if the acceptance condition is met |Xi-X 2 |<г, (10) where X 1 and X 2 are the results of two parallel determinations, %; g - repeatability (convergence) limit of two parallel determinations, %, given in Table 5. 10.6.3 Characteristics of the error in determining the mass fraction of fat in confectionery products containing milk and products of its processing, with a confidence probability of P = 0.95 are given in Table 5. Appendix A (mandatory) Corrections for refractometric determination of the refractive indices of a solution of fat and a mixture of fats in a solvent at temperatures from 15 °C to 35 °C A.1 Corrections for the refractometric determination of the refractive indices of a solution of fat and a mixture of fats in a solvent at temperatures from 15 °C to 35 °C are given in Table A.1. Table A.1 Temperature, °C Amendment Temperature, °C Amendment Subtract from the found refractive index Add to the found refractive index Adopted by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 47-2015 of June 18, 2015) Registered by the Bureau of Standards MGS No. 11054 The date of entry into force of this change is determined by the specified national standardization bodies* Clause 7.4.1. Fourth, fifth paragraphs. Delete the words: “with an error of no more than 0.001 g”; last paragraph. Replace the claim and paragraph numbers: “(1)” with “(1a)”, “7.5.1” with “7.5.1a”. Subsection 7.5 should be supplemented with paragraph - 7.5.1a (before paragraph 7.5.1): t-\) 50-100 ~t20 “7.5.1 a The mass fraction of fat with preliminary hydrolysis of the product and extraction with chloroform U m s,%, in flour and sugar confectionery products and semi-finished products is calculated using the formula where m is the mass of the empty flask, g; t 2 - mass of the flask with the resulting fat, g; 50 - volume of chloroform taken to dissolve fat, cm 3; t is the mass of the analyzed sample, g; 20 - volume of filtrate taken for distillation, cm 3. Calculations are carried out to the second decimal place, followed by rounding to the first decimal place. The final result of determining the mass fraction of fat with preliminary hydrolysis of the product and extraction with chloroform in flour and sugar confectionery products and semi-finished products is taken as the arithmetic mean of the results of two parallel determinations performed under repeatability conditions, if the acceptance condition according to formula (2) given in 7.5.1 is met. " Clause 7.5.1. The first paragraph after the words “Mass fraction of fat” should be supplemented with the words: “with preliminary hydrolysis of the product and extraction with petroleum ether.” Clauses 7.5.2,8.5.2,9.5.4,10.6.3. Tables 1,2,4,5. Column “Measurement range of mass fraction, %”. Replace the values: “from 0 to 60” with “From 2 to 60”. Date of entry into force on the territory of the Russian Federation - 2016-01-01. Refrigerator KhPT 1-300-14/23 THS according to GOST 25336.” Subsection 9.2. Fourth paragraph. Replace the words: “at the cost of dividing 1 °C” with “at the cost of dividing 0.1 °C”; add a paragraph (before the last one): “A water bath or a water thermostat that ensures that the temperature is maintained from 20 °C to 100 °C.” Clauses 9.3.3 (first, second paragraphs), 9.3.4 (second paragraph). Delete the words: “with an error of no more than 0.0015 g.” Subsection 9.4. First paragraph. Replace the words: “with an error of no more than 0.001 g” with “with recording the weighing result to the third decimal place”; Table 3 should be presented in a new edition: Subsection 10.5. First paragraph. Replace the words: “with an error of no more than 0.001 g” with “with recording the weighing result to the third decimal place.” (IMS No. 11 2015) Confectionery Methods of determination of fat weight fraction Date of introduction -2014-01-01 This standard applies to confectionery products and semi-finished products and establishes extraction-weight and refractometric methods for determining the mass fraction of fat. This standard uses normative references to the following interstate standards: The method is based on the extraction of fat from the analyzed product sample with a solvent and determination of the mass fraction of fat after removal of the solvent. Laboratory scales with limits of permissible absolute error of single weighing + 0.2 mg. Liquid thermometer with a measurement range from 0 °C to 100 °C and a division value of 1 °C according to GOST 28498. 1 An electric laboratory drying cabinet with a thermostat that ensures that the temperature in the working chamber is maintained at (100 + 2) °C. Laboratory centrifuge with a speed of at least 3000 revolutions per minute and heat-resistant centrifuge tubes with caps with a capacity of 50 cm 2. The electric stove is a closed type, providing heating in the temperature range from 80 °C to 200 °C according to GOST 14919. Water bath, ensuring temperature maintenance up to 100 °C. Soxhlet apparatus consisting of: nozzles NET-250 TS. 1,2-Dichloroethane technical according to GOST 1942. Chloroform (trichloromethane) according to GOST 20015. Petroleum ether with a boiling point of 40 °C-70 °C and a density of 0.64-0.65 g/cm2. Silver nitrate x. parts according to GOST 1277. It is allowed to use other measuring instruments and auxiliary equipment with metrological and technical characteristics and reagents of quality not lower than those specified. 200-250 cm2 of distilled water is placed in a volumetric flask with a capacity of 1000 cm2. Add 609 cm 2 of concentrated hydrochloric acid with a density of 1.198 g/cm 2 . The volume of the solution is adjusted to the mark with distilled water. 400-500 cm2 of distilled water is placed in a volumetric flask with a capacity of 1000 cm2. Add 27.2 cm 2 of concentrated sulfuric acid with a density of 1.84 g/cm 2 . The volume of the solution is adjusted to the mark with distilled water. 400-500 cm2 of distilled water is placed in a volumetric flask with a capacity of 1000 cm2. Add 34.8 cm 2 of concentrated hydrochloric acid with a density of 1.198 g/cm 2 . The volume of the solution is adjusted to the mark with distilled water. The shelf life of solutions of hydrochloric and sulfuric acids in tightly closed glass containers in a fume hood at room temperature is no more than two weeks. 16.99 g of silver nitrate is placed in a volumetric flask with a capacity of 1000 cm2, and 400-500 cm2 of distilled water is added. The volume of the solution is adjusted to the mark with distilled water. The solution must be freshly prepared. Place 1.0 g of phenolphthalein in a volumetric flask with a capacity of 100 cm3, add 40-50 cm3 of ethyl alcohol and mix thoroughly until completely dissolved. The volume of the solution is adjusted to the mark with distilled water. The solution is stored in a glass container at room temperature. 3-5 g of the crushed analyzed sample is weighed, recording the result to the third decimal place, placed in a conical flask with a capacity of 250 cm 3, 100 cm 3 of 1.5% hydrochloric acid (or 100 cm 3 of 5% sulfuric acid) is added, boil in a flask with reflux over low heat for 30 minutes. Then the flask is cooled with water to room temperature, 50 cm 3 of chloroform is added, tightly closed with a well-fitting stopper, shaken vigorously for 15 minutes, the contents are poured into centrifuge tubes and centrifuged for 2-3 minutes at a speed of 3000 rpm. Three layers are formed in the test tube. The upper aqueous layer is removed using a separatory funnel. Delamination can also occur in the following way. After hydrolysis, 5 cm 3 of ammonia solution with a density of 910.0 kg/m 3.50 cm 3 of chloroform is added to the cooled flask. The contents of the flask are shaken for 15 minutes and left to settle for 1 hour. During this time, the lower chloroform layer is completely separated and becomes clearly visible. If separation does not occur, add another 2-3 cm 3 of ammonia, making sure that the reaction for phenolphthalein remains acidic. Using a pipette equipped with a rubber bulb, a chloroform fat solution is taken and filtered into a dry flask through a small cotton swab inserted into the narrow part of the funnel, with the tip of the pipette touching the cotton wool. 20 cm 3 of the filtrate is placed in a flask with a capacity of approximately 100 cm 3, previously brought to a constant mass (the difference between two successive weighings should not exceed 0.001 g) and weighed with an error of no more than 0.001 g. The weighing result is recorded to the second decimal place. Filtration and selection should be carried out within 2 minutes, the chloroform from the flask is distilled off in a hot bath using a refrigerator with a straight tube. The fat remaining in the flask is dried to a constant weight (the difference between two successive weighings should not exceed 0.001 g) for 1.0-1.5 hours at a temperature of 100 °C, then cooled in a desiccator for 20 minutes and the flask is weighed with an error of no more than 0.001 g. The weighing result is recorded to the second decimal place. Two parallel determinations are carried out and the mass fraction of fat is calculated using formula (1) given in 7.5.1. 10-15 g of the prepared sample with the weighing result recorded to the third decimal place is placed in a glass beaker and 45 cm 3 of distilled water at a temperature of 60 °C-70 °C is slowly poured into it with constant stirring until a homogeneous suspension is obtained. Then add 55 cm 3 of hydrochloric acid with a molar concentration of (HCI) = 8 mol/dm 3 (8 N) and mix. Cover with a watch glass, then slowly bring to a boil and simmer for 15 minutes. Rinse the watch glass with 100 cm 3 of distilled water and filter the contents of the glass through a paper filter, rinsing the glass with distilled water. The filter cake is washed with distilled water until there is a complete absence of 01“ ions in the filtrate, which is confirmed by the absence of turbidity when adding a silver nitrate solution of molar concentration with (AgN0 3) = 0.1 mol/dm 3 (0.1 n) to the filtrate and stirring the resulting mixtures. The filter with the sediment is dried in a glass beaker in an oven at a temperature of 100 °C. The dried filter with sediment is placed in a paper cartridge and the fat is extracted with petroleum ether in a Soxhlet apparatus, using as a fat receiver a pre-defatted conical flask with a capacity of 250 cm 3, dried for 1 hour at a temperature of 100 ° C and weighed, recording the weighing result to the third decimal sign. Rinse the beaker for hydrolysis, the watch glass (previously dried) and the beaker for drying with three 50 cm 3 portions of petroleum ether and add it to the Soxhlet apparatus flask. Extract the fat for 4 hours. Separate the flask from the Soxhlet apparatus and slowly evaporate the solvent in a water bath in a fume hood. Carbon tetrachloride according to GOST 20288. Ethyl ether (sulfur), analytical grade. It is allowed to use other measuring instruments and auxiliary equipment with metrological and technical characteristics and reagents of quality not lower than those specified. 5-10 g of crushed analyzed sample is calculated so that it contains 1-2 g of fat and weighed. The weighing result is recorded to the second decimal place. Confectionery products, the production processes of which include heat treatment of raw materials and semi-finished products above 70 °C, are subjected to the following processing. 15-20 cm 3 of distilled water and 20 cm 3 of concentrated hydrochloric acid are poured into the glass with the sample being analyzed, the contents are mixed with a glass rod, the glass is covered with a watch glass, and the contents are heated in a boiling water bath for 5 minutes. Then the watch glass is rinsed with hot distilled water over the glass. Prepare a funnel with a filter, moisten the filter with distilled water, transfer the contents of the glass to the filter, allow the liquid to drain and wash the residue on the filter at least four times with distilled water at a temperature of 60 °C-70 °C, preventing the filter from drying out. The washed filter is removed from the funnel, placed in a weighing bottle and dried in an oven at a temperature of 105 ° C to constant weight (the difference between two successive weighings should not exceed 0.001 g). Confectionery products such as chocolate, halva and others, the production processes of which do not involve heat treatment above 70 °C, may not be treated with hydrochloric acid. The analyzed sample of the crushed product or a dried filter with the analyzed sample treated with acid is placed in a paper cartridge, on the bottom of which a piece of cotton wool is preliminarily placed and which is sealed so as to close the cracks at the bottom. The top of the cartridge is also tightly covered with cotton wool. The cartridge is placed in the extractor, a refrigerator and a receiving flask are attached to the extractor. The receiving flask is pre-dried in an oven to constant weight at a temperature of 105 °C, cooled in a desiccator to room temperature and weighed. The weighing result is recorded to the second decimal place. Having placed the cartridge in the Soxhlet device, add a solvent (carbon tetrachloride, or chloroform, or ethyl ether), after rinsing the bottle in which the filter with the analyzed sample was dried. The amount of solvent should be 1.5 times the volume of the extractor when filling it to the upper elbow of the siphon. Extraction is carried out for at least 5 hours from the analyzed sample not treated with hydrochloric acid, and for at least 3.5 hours from the analyzed sample treated with hydrochloric acid. To determine the end of the process, 1-2 cm 3 of liquid is taken from the extractor, applied to a dry watch glass and placed in a fume hood until the solvent has completely evaporated. If the glass is clear after the solvent evaporates, the extraction is complete. At the end of the process, the flask with the extract is cooled, the refrigerator and the extractor are disconnected. Then attach the receiving flask to a direct condenser and distill off the solvent. After this, the flask is placed in a boiling water bath and the remaining solvent is distilled off. Hourglass at 1,2,3 minutes. Pycnometer type PZh2 with a neck diameter of 6 mm, capacity 25.50 cm 3 according to GOST 22524. Pipettes 1-2-1-2 according to GOST 29227. GOST 5899-85 INTERSTATE STANDARD CONFECTIONERY PRODUCTS Methods for determining the mass fraction of fat Confectionery Methods for determination of fat fraction of total mass MKS 67.180.10 Date of introduction 1986-07-01 ENTERED INTO EFFECT by Resolution of the USSR State Committee on Standards dated August 30, 1985 N 2823 This standard applies to confectionery products and semi-finished products and establishes refractometric and extraction-gravity methods for determining the mass fraction of fat. 1. SAMPLING METHODS 1.1. Sampling - according to GOST 5904-82. 2.1. The method is based on extracting fat from a sample with monobromo- or monochloronaphthalene and determining the refractive index of the solvent and fat solution. 2.2. Equipment, materials and reagents 2.3. Preparing for the test 2.3.1. Checking the refractometer zero point If the chiaroscuro boundary passes through the point of intersection of the sighting lines, then the device is set to zero. If this is not the case, then using a special key and screw, place the border of light and shadow at the point of intersection of the sighting lines. 2.3.2. Determination of the refractive index of a solvent 2.3.3. Determination of solvent density where is the mass of the empty pycnometer, g; 2.3.3.1. The result of the determination is calculated accurate to the first decimal place. The final result is rounded to the nearest whole number. 2.3.4. Solvent Pipette Calibration where is the mass of the solvent corresponding to the volume of the pipette taken, g; 2.3.4.1. The result is calculated accurate to the fourth decimal place. The final result is rounded to the third decimal place. 2.4. Carrying out the test The sample is placed in a porcelain mortar or porcelain cup, ground with a pestle for 2-3 minutes, then 2 cm of solvent is added with a pre-calibrated pipette according to clause 2.3.4 and the whole thing is ground again for 3 minutes, the contents are filtered through a paper filter into a small glass or other laboratory dishes The filtrate is stirred with a glass rod. 2 drops of the filtrate are applied to the prism of a refractometer at a temperature of (20.0±0.1) °C and the refractive index is measured. 2.5. Processing the results 2.5.1. The mass fraction of fat () as a percentage is calculated using the formula where is the volume of solvent taken to extract fat, cm; 2.5.2. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula where is the mass fraction of moisture in the product under study, %. 2.5.3. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place. 2.5.4. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between which in one laboratory should not exceed 0.3% in absolute value, and those performed in different laboratories - 0.5%. 1. When calculating the mass fraction of fat, use the refractive indices and density of fats given in Appendix 2. 2. If the product under study contains a mixture of fats (for example, cocoa butter and butter in chocolate with milk, nut butter, cocoa butter and confectionery fat in candy boxes, etc.), the refractive index and density can be determined by calculation (see Appendix 4). 3. For unknown fats and mixtures of fats, the density is taken to be 930 kg/m. 4. If the test product contains more than 5% water, then the mortar with the sample is placed in a drying cabinet and the sample is dried at a temperature of 100 ° C - 105 ° C for 30 minutes, then the solvent is poured into the mortar, after it has cooled to room temperature, with a micropipette . 5. When the sample with the solvent is well ground in a mortar, when the mixture is transferred to the filter, it is allowed to apply drops of the fat solution in the solvent flowing from the funnel onto the prism of the refractometer, without waiting for the entire mixture to be filtered. 3.1. The method is based on the extraction of fat from a sample with monobrome or monochloronaphthalene after pre-treatment with acetic acid; The refractive index is determined after drying the extract with anhydrous sodium carbonate. 3.2. Equipment, materials and reagents 3.3.1. Checking the refractometer according to clause 2.3.1. 3.3.2. Determination of the refractive index of the solvent according to clause 2.3.2. 3.3.3. Determination of solvent density according to clause 2.3.3. 3.3.4. Calibration of the pipette according to the solvent according to clause 2.3.4. 3.4. Carrying out the test When determining the fat in iris, add 1 cm of water to the sample, for other products - 0.5 cm of water. The sample is completely dissolved in a hot water bath, then cooled to room temperature, about 1 g of clean dry river sand and 1 cm of acetic acid with a mass fraction of 80% are added, everything is thoroughly ground for 2 minutes, after which 2 cm of monobromo or monochloronaphthalene is added and grind for 3 minutes, add 2 g of anhydrous sodium carbonate when analyzing iris (1 g for other products), mix thoroughly for about 1 minute and filter the contents through a paper filter into a small glass. The filtrate is stirred with a glass rod. 3.5. Processing the results 4.1. The method is based on extracting fat from a pre-hydrolyzed sample of the product with a solvent and determining the amount of fat by weighing after removing the solvent from a certain volume of the resulting solution. 4.2. Equipment, materials and reagents 4.3. Testing 4.3.1. A sample of the crushed test product in the amount of 10 g (if the fat content in the products is over 10%, the sample can be reduced to 5 g) is weighed with an error of no more than 0.01 g, placed in a conical flask with a capacity of 250 cm3, 100 cm3 of 1.5% is added. hydrochloric acid (or 100 cm of 5% sulfuric acid), boil in a flask with reflux over low heat for 30 minutes. Then the flask is cooled with water to room temperature, 50 cm of chloroform is added, tightly closed with a well-fitting stopper, shaken vigorously for 15 minutes, the contents are poured into centrifuge tubes and centrifuged for 2-3 minutes. Three layers are formed in the test tube. The top aqueous layer is removed. Using a pipette equipped with a rubber bulb, take a chloroform solution of fat and filter it into a dry flask through a small cotton swab inserted into the narrow part of the funnel, with the tip of the pipette touching the cotton wool. 20 cm of the filtrate is placed in a flask with a capacity of approximately 100 cm, previously brought to a constant mass and weighed with an error of no more than 0.001 g. 4.3.2. The following delamination method is allowed. After hydrolysis, 5 cm of ammonia solution (density 910.0 kg/m) and 50 cm of chloroform are added to the cooled flask. The contents of the flask are shaken for 15 minutes and left to settle for 1 hour. During this time, the lower chloroform layer is completely separated and becomes clearly visible. If separation does not occur, add another 2-3 cm of ammonia, making sure that the phenolphthalein reaction remains acidic. 1. Distillation and filtration of the solvent is carried out under a hood. 2. In the absence of chloroform, the use of dichloroethane is allowed, which should be stored in dark bottles. 4.4. Processing the results 4.4.1. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula where is the mass of the flask with dried fat, g; 4.4.2. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place. 4.4.3. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between them in absolute value should not exceed 0.5%. The limit of possible measurement error is 0.8% (0.95). 5.1. The method is used when disagreements arise to determine the mass fraction of fat in all confectionery products and semi-finished products. 5.2. Equipment, materials and reagents 5.4. Testing 5.5.1. The mass fraction of fat () as a percentage is calculated using the formula where is the mass of the receiving flask without fat, g; 5.5.2. The mass fraction of fat () as a percentage in terms of dry matter is calculated using the formula where is the mass fraction of moisture in the product under study, %. 5.5.3. The results of parallel determinations are calculated accurate to the second decimal place. The final result is rounded to the first decimal place. 5.5.4. The final test result is taken as the arithmetic mean of the results of two parallel determinations, the permissible differences between which in one laboratory should not exceed 0.3% in absolute value, and those performed in different laboratories - 0.5%. 6.1. The solvents used - ethyl ether, chloroform (trichloromethane), ethylene chloride (dichloroethane) and carbon tetrachloride must comply with the safety requirements regulated by regulatory and technical documentation, GOST 20015-88, GOST 1942-86, GOST 20288-74. 6.2. Work with all solvents must be carried out only under traction. 6.3. When working with solvents, do not use open flame. ANNEX 1 Temperature, °C Amendment APPENDIX 2 Name of fats Density, kg/m Refractive index Cocoa butter Confectionery fat Margarine Soybean oil Sunflower oil Cow butter Corn oil Coconut oil Sesame oil Shocklin type fats Phosphatide concentrates Cooking fat Nut oil: peanuts almonds hazelnuts Apricot kernel oil Rendered pork fat APPENDIX 3 Temperature, °C Amendment Subtract from the found refractive index Add to the found refractive index APPENDIX 4 An example of calculating the refractive index and density of a mixture of fats name of raw materials Mass fraction of dry substances, % Total consumption of raw materials per 1 ton of unwrapped sweets, kg Mass fraction of fat Refractive index of fat Fat density at in dry matter Chocolate glaze Granulated sugar Powdered sugar Roasted almond kernel Cocoa liquor Butter Cacao butter Vanillin Liquefier To calculate the refractive index of a mixture of fats, the resulting sum of the products of fat masses and the refractive index (column 8) should be attributed to the sum of fat masses (column 6) To calculate the density of a fat mixture, the resulting sum of the products of fat masses and fat density (column 10) should be attributed to the sum of fat masses (column 6) ROSSTANDART
FSUE STANDARDINFORM
FA ON TECHNICAL REGULATION
In GOST 5899-85 “Confectionery products. Method for determining the mass fraction of fat" two methods of determination are given: extraction and refractometric. The extraction method gives the most accurate results and is therefore used as the arbitration method for all sugar confectionery products. The method is based on fat extraction with a solvent in a special Soxhlet apparatus. The fastest and least labor-intensive is the refractometric method. The method is based on determining the refractive index of fat extracted from a sample with a solvent. The refractive index of the solvent must be significantly different from the refractive index of the fat. The greater the difference, the more accurate the results. The solvent should not dissolve water and should be low-volatile. These requirements are met by monobromonaphthalene with a refractive index of 1.63. To determine the refractive index of a solvent, 1-2 drops of solvent are applied to the prism of a universal refractometer with a limiting refractive index of 1.7 at a temperature of 20 C and the refractive index of the solvent is read off on a scale. The refractometric method has two options. The first version of the method is used to determine the mass fraction of fat in chocolate, praline, halva, and marzipan. First, using Table 16, determine the mass of the sample, after which the required amount of crushed product is weighed with an accuracy of 0.001 g. Table 16. Dependence of sample weight on fat mass fraction The sample is placed in a porcelain mortar or cup, ground with a pestle for 2-3 minutes, 2 cm 3 of solvent is added (with a previously calibrated pipette) and grinding continues for another 3 minutes. The contents of the cup are then filtered into a dry cup through a folded paper filter placed in a small funnel, discarding the first 2-3 drops. The filtrate is carefully mixed with a glass rod, 2 drops are applied to the prism of the refractometer and the refractive index is measured. The determinations are carried out at least 3 times and the arithmetic mean of the measurements is taken as the final result. The duration of filtration and determination of the refractive index should be no more than 30 minutes to avoid evaporation of the solvent. The measurement of the refractive index of the studied filtrate is usually carried out at 20° C. The mass fraction of fat X,%, in terms of dry matter is calculated using the formula where Vp is the volume of solvent taken to extract fat, cm 3; Rzh - relative density of fat at 20° C, g/cm 3 ; Pr is the refractive index of the solvent; Prz - refractive index of a solution of fat in a solvent; Rf - refractive index of fat, determined according to table 139; 100 - conversion factor to percentage; W - humidity of this product, %. If the product contains an unknown fat or a complex mixture of fats, then the fat is first extracted from 5-10 g of the product with a threefold amount of chloroform, shaking the flask for 15 minutes, filtered, the solvent is distilled off, the residue is dried and the refractive index is determined. For a mixture of fats or unknown fat, Rf is taken to be approximately 0.93. Table 17. Refractive indices and density of fats 20 0 C Name of fat Refractive index Density, g/cm 3 Sesame oil Sunflower oil Cow butter Margarine Peanut butter Mustard oil Confectionery fat Soybean oil Corn oil Phosphatide concentrates Cooking fat Rendered pork fat Cocoa butter The second version of the refractometric method is recommended for determining the mass fraction of fat in confectionery products such as toffee, fudge, creamy toffee, “Start”, “Korovki” candies, etc. To carry out the analysis, you will need the same equipment, auxiliary materials and glassware as in the first version of the method. Progress of determination Weigh the pre-crushed test sample in an amount of approximately 1.5 g with an accuracy of 0.001 g, transfer the sample into a mortar or porcelain cup, add 0.5 cm 3 (for iris 1 cm 3) of water and, placing the cup in a hot water bath, achieve complete dissolution of the product. After cooling the solution to room temperature, add about 1 g of clean dry sand and 1 cm 3 of acetic acid solution to the cup, thoroughly grind the contents (about 3 minutes), add 1 g (for iris 2 g) dry sodium carbonate, stir for another 1 minute and filter through a funnel with a paper filter. 2 drops of the filtrate are applied to the refractometer prism and the refractive index is determined. Measurements are carried out at least three times and the arithmetic mean is taken as the test result. If the refractive index was determined at 20° C, when calculating the mass fraction of fat (per dry matter) using formula 43, the values of the refractive index of fat in the solvent obtained in the experiment are used.10 Refractometric method for determining the mass fraction of fat in confectionery products containing milk and its products
10.1 Essence of the method
10.3 Preparation of a solution of acetic acid with a mass fraction of 80%
10.4 Preparing to take measurements
10.5 Taking measurements
10.6 Processing results
Change No. 1 GOST 31902-2012 Confectionery products. Methods for determining the mass fraction of fat
INTERSTATE STANDARD
CONFECTIONERY PRODUCTS Methods for determining the mass fraction of fat
1 area of use
2 Normative references
7 Extraction-weight method for determining the mass fraction of fat in flour and sugar confectionery products and semi-finished products
7.1 Essence of the method
7.2 Measuring instruments, auxiliary equipment, glassware, reagents and materials
GOST 31902-2012
7.3 Preparation of solutions
7.3.1 Preparation of a solution of hydrochloric acid of molar concentration with (HCI) = = 8 mol/dm 2 (8 n)
7.3.2 Preparation of a solution of sulfuric acid with a mass fraction of 5.0%
7.3.3 Preparation of a solution of hydrochloric acid with a mass fraction of 1.5%
7.3.4 Preparation of a silver nitrate solution of molar concentration c(AgN0 3) = = 0.1 mol/dm 2 (0.1 n)
7.3.5 Preparation of an alcohol solution of phenolphthalein with a mass fraction of 1%
7.4 Taking measurements
7.4.1 Determination of the mass fraction of fat with preliminary hydrolysis of the product and extraction with chloroform
7.4.2 Determination of the mass fraction of fat by preliminary hydrolysis of the product and extraction with petroleum ether
8.3 Preparing to take measurements
8.4 Taking measurements
Group H49
OKSTU 9109
The validity period was lifted according to Protocol No. 5-94 of the Interstate Council for Standardization, Metrology and Certification (IUS 11-12-94)
INSTEAD GOST 5899-63
REISSUE1. SAMPLING METHODS
2. REFRACTOMETRIC METHOD FOR DETERMINING THE MASS FRACTION OF FAT IN CONFECTIONERY PRODUCTS AND SEMI-FINISHED PRODUCTS
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g according to GOST 24104-88* or other scales that meet the specified requirements for their metrological characteristics.
_________________
* On July 1, 2002, GOST 24104-2001 came into force (hereinafter).
Hourglass at 1, 2, 3 minutes.
Desiccator according to GOST 25336-82.
Porcelain mortar with a diameter of no more than 70 mm with a pestle in accordance with GOST 9147-80 or evaporating bowl 1, 2 or 3 in accordance with GOST 9147-80.
Conical flask with ground stopper in accordance with GOST 25336-82, nominal capacity 25, 50, 100 cm.
Technical ethyl alcohol according to GOST 17299-78.
Ethyl ether (dehydrated).
Before starting to work with a refractometer, check the zero point of the device using distilled water. To do this, 1-2 drops of distilled water are placed between the prisms, then the scale eyepiece and the telescope eyepiece are adjusted to sharpness so that the field of view and sight lines are clearly visible.
The sighting line of the scale eyepiece is set to 1.333 (the refractive index of distilled water at 20 °C) and the chiaroscuro boundary is observed through the telescope in relation to the intersection point of two mutually perpendicular sighting lines.
The device must be checked at a prism temperature of 20 °C. Temperature is measured with a thermometer specially mounted near the prisms of the refractometer. The required temperature is established by passing water at a given temperature.
In each batch of monobromo- or monochloronaphthalene received for analysis, the refractive index is determined with an error of no more than 0.0001 by applying 1-2 drops of this solvent to the refractometer prism at a temperature of (20.0±0.1) °C.
The pycnometer, dried at a temperature of 100 ° C - 105 ° C to constant weight and cooled in a desiccator to room temperature, is weighed with an error of no more than 0.0015 g and filled using a small funnel with distilled water slightly above the mark.
The pycnometer is closed with a stopper and kept for 20 minutes in a water thermostat or water bath at a water temperature of (20.0±0.1) °C. At this temperature, the water level in the pycnometer is brought to the mark using a capillary tube or a strip of filter paper rolled into a tube. The pycnometer is again closed with a stopper and kept in a thermostat or water bath for another 10 minutes, checking the position of the meniscus in relation to the mark. Then the pycnometer is removed from the thermostat or water bath, wiped dry from the outside with a soft cloth, left under the glass of an analytical balance for 20 minutes and weighed with an error of no more than 0.0015 g.
Then it is freed from water, rinsed successively with ethyl alcohol and ether, dried as indicated above, cooled in a desiccator to room temperature and filled with the test solvent, after which the same operations are performed as with distilled water.
Filling the pycnometer with water (or solvent), installing the meniscus and weighing is repeated three times. The discrepancies between parallel weighings should not be more than 0.005 g. The arithmetic average is taken for calculation.
Solvent density () in kg/m is calculated using the formula
- mass of the pycnometer with distilled water, g;
- mass of pycnometer with solvent, g;
998.23 - value of water density at 20 °C, kg/m.
Calibration is carried out for each newly used pipette.
A pipette with a capacity of 2 cm is calibrated by the solvent, measuring with it the corresponding volume of monobromine or monochloronaphthalene and weighing it in a pre-weighed flask with a ground stopper or a weighing cup with an error of no more than 0.0015 g. The discrepancy between parallel weighings should be no more than 0.005 g. Weighing is carried out three times. For the calculation, the arithmetic mean is taken.
The volume of the pipette () in cm is calculated using the formula
- density of the solvent at a temperature of 20 °C, determined according to clause 2.3.3, kg/m.
A sample of the crushed test product is weighed with an error of no more than 0.001 g.
The weight of the sample is determined from the table.
The refractive index is determined at least three times and the arithmetic mean value of the measurement results is taken as the test result.
To avoid evaporation of the solvent, the duration of filtration and determination of the refractive index should be no more than 30 minutes.
If the determination of the refractive index was not carried out at 20 °C, then a correction must be made. If, when determining the refractive index, the temperature of the refractometer prisms is within the range of 15 °C - 20 °C, the correction should be subtracted from the value of the refractive index; if the determination is carried out within the temperature range of 20 °C - 35 °C, then the correction should be added to the found refractive index the corresponding amendment in accordance with Appendix 1.
- fat density at 20 °C, kg/m;
- refractive index of the solvent;
- refractive index of a fat solution in a solvent;
- refractive index of fat;
- weight of the product sample,
Notes:
The refractive index of a mixture of fats can also be determined by extracting fat from the test product as follows: 5-10 g of the crushed product is mixed with 15-20 cm of ethyl or petroleum ether, chloroform or carbon tetrachloride, shaken for 10 minutes, the extract is filtered into a flask, the solvent is completely distilled off, the residue is dried in an oven at a temperature of 100-105 ° C for 30 minutes and the refractive index of the fat mixture is determined according to clause 2.4, taking into account the correction for temperature according to Appendix 3. 3. REFRACTOMETRIC METHOD FOR DETERMINING THE MASS PERCENTAGE OF FAT IN CONFECTIONERY PRODUCTS TYPE TOFFISH, CREAM FANDE, CANDIES “START”, “KOROKA”, etc.
A universal refractometer (URL) with a limiting refractive index of up to 1.7 or a refractometer of another system.
Electric drying cabinet with contact or technical thermostat.
Laboratory mercury glass thermometer in accordance with GOST 28498-90 and normative and technical documentation.
Hourglass at 1, 2, 3 minutes.
Water bath.
Desiccator according to GOST 25336-82.
Pycnometer type PZh2 with a neck diameter of 6 mm in accordance with GOST 22524-77, capacity 25, 50 cm.
Pipettes version 1 or 4, 2nd accuracy class according to GOST 29169-91, capacity 2 cm.
Glass glasses according to GOST 25336-82, capacity 25, 50 cm.
Glass funnels with a diameter of no more than 40 mm in accordance with GOST 25336-82.
Laboratory filter paper according to GOST 12026-76.
Porcelain mortar with a diameter of no more than 70 mm with a pestle in accordance with GOST 9147-80 or evaporating bowl 1, 2, 3 in accordance with GOST 9147-80.
The solvent is bromonaphthalene (monobromonaphthalene) with a refractive index of about 1.66 or -chloronaphthalene (monochloronaphthalene) with a refractive index of about 1.63.
Acetic acid according to GOST 61-75, chemically pure, solution with a mass fraction of 80%.
Anhydrous sodium carbonate according to GOST 83-79, chemical grade.
3.3. Preparing for the test
A sample of the crushed test product in an amount of about 1.5 g is weighed with an error of no more than 0.001 g and placed in a porcelain mortar or porcelain cup.
2 drops of the filtrate are applied to the prism of a refractometer at a temperature of (20.0±0.1) °C and the refractive index is measured.
The refractive index is determined at least three times and the arithmetic mean of the measurement results is taken as the test result.
If the determination was not carried out at 20 °C, then an amendment should be made according to clause 2.4 (see Appendix 1).
The results are processed according to clause 2.5 of section 2. 4. EXTRACTION-GRAVE METHOD FOR DETERMINING THE MASS FRACTION OF FAT IN FLOUR CONFECTIONERY PRODUCTS AND FINISHING AND BAKED SEMI-FINISHED PRODUCTS
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g and 3rd class with a maximum weighing limit of 1 kg according to GOST 24104-88 or other scales that meet the specified requirements for their metrological characteristics.
Electric drying cabinet with contact or technical thermostat.
Hourglass at 1, 2, 3 minutes.
Laboratory centrifuge.
Electric stove.
Desiccator according to GOST 25336-82.
Water bath.
Flasks type Kn, version 1, 2 according to GOST 25336-82, capacity 100, 250 cm.
Cylinders of execution 1, 3 according to GOST 1770-74, capacity 100 cm.
Pipettes version 2, 2nd accuracy class, according to GOST 29169-91, capacity 20, 50 cm.
Ball refrigerator according to GOST 25336-82.
Refrigerator with a straight tube according to GOST 25336-82.
Glass glasses according to GOST 25336-82, capacity 25, 50 cm.
Glass funnels according to GOST 25336-82.
Laboratory filter paper according to GOST 12026-76.
Rubber bulb.
Hydrochloric acid according to GOST 3118-77, solution with a mass fraction of 1.5%, chemical grade.
Sulfuric acid according to GOST 4204-77, solution with a mass fraction of 5%, chemical grade.
Chloroform (trichloromethane) according to GOST 20015-88 or
Ethylene chloride (dichloroethane) according to GOST 1942-86 with a density of 1252.0-1253.5 kg/m.
Ammonia water according to GOST 3760-79.
Phenolphthalein according to NTD, alcohol solution with a mass fraction of 1%.
Filtration and selection should be carried out within 2 minutes, the chloroform from the flask is distilled off in a hot bath using a refrigerator with a straight tube. The fat remaining in the flask is dried to a constant weight, usually 1-1.5 hours, at a temperature of 100 ° C - 105 ° C, cooled in a desiccator for 20 minutes and the flask is weighed with an error of no more than 0.001 g.
After separation, selection, filtration, distillation of the chloroform layer and drying of the fat are carried out according to clause 4.3.1.
Notes:
- mass of the empty flask, g;
50 - volume of chloroform taken to dissolve fat, cm;
- weight of the sample, g;
20 - volume of chloroform solution of fat taken for distillation, cm;
- mass fraction of moisture in the product under study, %.5. EXTRACTION-GRAVE METHOD
The method is based on the extraction of fat with a solvent directly from a sample or from a sample pre-treated with hydrochloric acid. After distilling off the solvent from the resulting extract, the residue is dried and weighed.
General purpose laboratory scales of the 2nd accuracy class with a maximum weighing limit of 200 g according to GOST 24104-88 or other scales that meet the specified requirements for their metrological characteristics.
Electric drying cabinet with contact or technical thermostat.
Electric stove.
Desiccator according to GOST 25336-82.
Water bath.
Soxhlet device.
Medical hygroscopic cotton wool according to GOST 5556-81.
Laboratory filter paper according to GOST 12026-76.
Glass glasses according to GOST 25336-82, capacity 100, 150 cm.
Weighing cups (bugs) in accordance with GOST 25336-82.
Laboratory funnels with a diameter of 50-70 mm according to GOST 25336-82.
Cylinder version 1 according to GOST 1770-74, capacity 25 cm.
Porcelain mortar with a diameter of 110-180 mm with a pestle in accordance with GOST 9147-80.
Watch glass.
Hydrochloric acid according to GOST 3118-77, concentrated, chemical grade.
Carbon tetrachloride according to GOST 20288-74 or
Chloroform according to GOST 20015-88, or
Ethyl ether (dehydrated) or
Petroleum ether according to regulatory and technical documentation.
Distilled water according to GOST 6709-72.
5.3. Preparing for the test
A sample of the crushed product is weighed with an error of no more than 0.001 g. The mass of a sample of 5-10 g is calculated depending on the mass fraction of fat in the product under study so that the sample contains about 1-2 g of fat.
Products with high humidity, which spread during grinding and form lumps (taffy, bird's milk candy bodies, toffee, etc.), after grinding are subjected to the following processing. 15-20 cm of distilled water and 20 cm of concentrated hydrochloric acid are poured into a weighed glass, the contents are mixed with a glass rod, the glass is covered with a watch glass, and the contents are heated in a boiling water bath for 5 minutes. Then the watch glass is rinsed with hot distilled water over the glass.
Prepare a funnel with a filter, moisten the filter with distilled water, transfer the contents of the glass to the filter, allow the liquid to drain and wash the residue on the filter at least four times with hot distilled water. When washing, the filter must be filled with water all the time, so it is filled with water immediately as soon as the previous portion of liquid has drained.
The washed filter is removed from the funnel, placed in a weighing bottle and dried in an oven at a temperature of 100 ° C - 105 ° C until constant weight.
Confectionery products with low moisture content (chocolate, halva, cookies) may not be treated with hydrochloric acid.
A sample of the crushed product or a dried filter with a sample treated with acid is placed in a paper cartridge, at the bottom of which a piece of cotton wool is preliminarily placed and which is sealed so as to close the cracks at the bottom. The top of the cartridge is also tightly covered with cotton wool. The cartridge is placed in the extractor, a refrigerator and a receiving flask are attached to the extractor. The receiving flask is pre-dried to constant weight at a temperature of 100 °C - 105 °C, cooled in a desiccator to room temperature and weighed with an error of no more than 0.001 g.
Having placed the cartridge in the Soxhlet extractor and assembled the entire device, add the solvent, rinsing it first with the bottle in which the filter with the sample was dried.
The amount of solvent should be 1.5 times the volume of the extractor when filling it to the upper elbow of the siphon.
Extraction is carried out for at least 5 hours from a sample not treated with acid, and for at least 3.5 hours from a sample treated with acid.
To determine the end of extraction, 1-2 cm of liquid is taken from the extractor, applied to a dry watch glass, and the solvent is evaporated. If the glass is clear after the solvent evaporates, the extraction is complete.
Once the extraction is complete, the flask containing the extracted fat and solvent is allowed to cool. Disconnect the flask, refrigerator and extractor. The receiving flask is connected to a direct condenser and the solvent is distilled off. After this, the flask is placed in a boiling water bath and the remaining solvent is removed.
To completely remove the solvent and moisture, the flask with fat is placed in a drying cabinet and kept at a temperature of 100 ° C - 105 ° C for 1 hour, then cooled in a desiccator and weighed with an error of no more than 0.001 g.
5.5. Processing the results
- mass of the receiving flask with fat, g;
- weight of the sample, g;
The limit of possible measurement error is 0.5% (0.95). 6. SAFETY REQUIREMENTS
APPENDIX 1 (mandatory). Correction for refractometric determination of the refractive indices of a solution of fat and a mixture of fats in a solvent for temperatures from 15 to 35 ° C
Mandatory
APPENDIX 2 (mandatory). Refractive indices and density of fats at 20 °C
Mandatory
APPENDIX 3 (mandatory). Correction for refractometric determination of the refractive index of fat and a mixture of fats for temperatures from 15 to 35 ° C
Mandatory
APPENDIX 4 (for reference). An example of calculating the refractive index and density of a mixture of fats in confectionery products.
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