GB/T 5009.202-2003 Determination of polar components (PC) in edible vegetable oils during frying

This standard specifies the determination of polar components in edible frying oil by column chromatography. This standard is applicable to the determination of polar components in vegetable oils, animal oils and refined oils used for frying various foods. GB/T 5009.202-2003 Determination of polar components (PC) in edible vegetable oils during frying GB/T5009.202-2003 Standard download decompression password: www.bzxz.net

ICS67.040
National Standard of the People's Republic of China
GB/T5009.202—2003
Replaces GB/T7102.2-1994
Determination of polar compouds in edible vegetable oils used in frying food
Determination of polar compouds in ediblevegetable oils used in frying foodIssued on August 11, 2003
Ministry of Health of the People's Republic of China
Administrative Committee of Standardization of the People's Republic of China
Implementation on January 1, 2004
GB/T5009.202—2003
This standard replaces GB/T7102.2—1994 "Determination of polar components (PC) in edible vegetable oils used in frying". Compared with GB/T7102.2-1994, this standard has been modified as follows: The Chinese name of the standard has been modified, and the Chinese name of the standard has been changed to "Determination of polar components (PC) in frying of edible vegetable oils":
The structure of the original standard has been modified in accordance with GB/T20001.4-2001 "Standard Preparation Rules Part 4: Chemical Analysis Methods".
Appendix A of this standard is a normative appendix.
This standard is proposed and managed by the Ministry of Health of the People's Republic of China. This standard is drafted by the Analysis and Testing Institute of Jilin Provincial Health and Disease Prevention Center. The main drafters of this standard are Yu Feng, Gao Binfu, Li Huaichun, Ding Jiahua, and Zhang Wei. The original standard was first issued in 1994, and this is the first revision. 588
1 Scope
Determination of polar components (PC) in frying of edible vegetable oils
This standard specifies the determination of polar components in edible frying oil by column chromatography. GB/T5009.202—2003
This standard applies to the determination of polar components in vegetable oils, animal oils and refined oils for frying various foods. 2 Terms and definitions
The following terms and definitions apply to this standard. Polar component polarcompound
Polar component refers to the deterioration of edible oil under the process conditions of frying food, and the occurrence of thermal oxidation reaction, thermal polymerization reaction, thermal oxidation polymerization reaction, thermal cracking reaction and hydrolysis reaction, which produces some components with greater polarity than normal vegetable oil molecules (triglycerides). It is the general term for the thermal oxidation products (triglycerides containing keto groups, hydroxyl groups, peroxide groups and carboxyl groups), thermal polymerization products, thermal oxidation polymerization products, and hydrolysis products (free fatty acids, monoglycerides and diglycerides) of triglycerides. 3 Principle
When the fried fat passes through a silica gel column with a certain amount of water adsorbed, the triglycerides (i.e. the fat that has not changed after frying) are eluted first and flow out of the column under the elution of the mobile phase. After evaporating the eluent, weigh it, which is the mass of the non-polar component. The mass of the polar component (the fat that has undergone chemical changes after frying) is subtracted from the mass of the column sample. 4 Reagents
4.1 Silica gel (for column chromatography): particle size range 60 mesh to 100 mesh, and the water content is about 5% according to the following method: dry the silica gel in an oven at 160℃ for 24 hours, then take it out and cool it to room temperature in a desiccator, then weigh 152g silica gel and 8g water, put them in a 500mL ground-mouth conical flask with a glass stopper, mechanically shake for 1 hour, and seal it for use. 4.2 Petroleum aldehyde (boiling range 30℃～60℃) + ether eluent: 87+13. 4.3 Sea sand: purified by calcination and acid washing. 4.4 10% vanadium phosphate ethyl solution colorimeter.
4.5 High-efficiency thin layer silica gel G plate (no fluorescence). 5 Instruments
Two types of chromatography columns are used. When the laboratory temperature is below 25℃, type A (commonly used) chromatography columns can be used. When the temperature exceeds 25℃, type B columns with circulating water jackets are used, see Figure 1. 589
GB/T5009.202—2003
6 Operation steps
6.1 Sample preparation
Inner diameter 21mm
Inner diameter 21mm
Preheat the frying oil sample slowly and mix thoroughly. If there are impurities and moisture, filter them out with filter paper. Use a small beaker to accurately weigh about 2.5g of oil sample (accurate to 0.01g). Quantitatively transfer to a 50mL volumetric flask, dilute with eluent and set aside. 6.2 Column loading
In order to prevent bubbles in the column, when the laboratory temperature is lower than 25℃, use type A column, and when the laboratory temperature is higher than 25℃, use type B column. When using type B column, the cooling water can be introduced into the jacket of the column by using the high-level bottle method to adjust the water to about 20℃ with ice cubes (if the tap water temperature is about 20℃, tap water can also be used) to ensure that the temperature of the column is lower than 25℃. First put a little glass wool at the bottom of the column, then add 30mL of eluent into the column. If there are bubbles, use glass wool to stir and drive away the bubbles. Weigh 35g silica gel (4.1) and add 80mL eluent (4.2) in a 100mL beaker. Use a glass rod without stirring to make the silica gel float as much as possible. Slowly pour it into the vertical chromatography column to make it flow evenly. Use a little eluent to clean the funnel and column wall. After sedimentation, release the eluent to 10cm above the silica gel surface. Gently shake to flatten the silica gel. Then add 4g sea sand into the column through the funnel, and then release the eluent to make it flush with the surface of the sea sand. 6.3 Column
Accurately draw 20mL of the prepared oil sample (6.1) and slowly transfer it to the chromatography column (6.2) along the column wall. Open the stopcock to make the sample liquid flush with the sea sand surface. 6.4 Elution of non-polar components
Cool the 400mL beaker and desiccator dried in an oven at 103℃±2℃ to room temperature and balance for 30 minutes. Weigh its mass ml on an analytical balance and place it under the column. Add 250mL of eluent (4.2). The elution rate is about 2mL/min. Wash until the liquid surface is flush with the sea sand surface. Then use a small amount of eluent to clean the outer wall below the stopcock and collect it in a beaker with a mass of m. This is the non-polar component. 6.5 Evaporation weighing plate
Put the eluent in the beaker in water at 90℃ and evaporate to dryness, then accurately weigh its mass m2.6.6 Calculationwww.bzxz.net
X=m-(mm2)×100
Wherein:
X polar component content, %;
mass of the oil sample on the column, in grams (g); mass of the empty cup, in grams (g):
the sum of the mass of the empty cup (m) and the mass of the non-polar component, in grams (g). Appendix A
(Normative Appendix)
Elution of polar components and thin layer chromatography monitoring GB/T5009.202—2003
Most of the polar components can be eluted, but due to their strong adsorption, they cannot be eluted 100%. The separation of them from the non-polar components can be monitored by thin layer chromatography.
A.1 Elution of polar components
If polar components need to be eluted, after washing off non-polar components, 150mL of eluent can be used to wash the polar components into a beaker of mass ms, evaporate to dryness according to 6.5, and then accurately weigh its mass m. The content of polar components can be calculated by the following formula: X=m-
(mgmg)
Where:
X-polar component content, %
empty cup mass, in grams (g);
the sum of the empty cup mass (m3) and the mass of polar components, in grams (g). m
A.2 Thin layer chromatography monitoring column chromatography
Use a micro syringe to gently spot about 2μL of the solution eluted from the column on the bottom edge of the chromatography plate 3cm away, so that the diameter of the spot is no more than 0.3cm. After the solvent evaporates, place the chromatography plate in a chromatography tank with a developing agent (petroleum ether + acetaldehyde + acetic acid, 70+30+2) and develop for about 15min (about 10cm away from the origin). Take out the chromatography plate, evaporate the solvent and spray the chromatography plate with 10% molybdophosphoric acid ethanol solution. Ethanol evaporates and heat in an oven at 120℃~130℃ until the spot is colored. The quality of column chromatography separation is judged according to the separation degree of polar and non-polar components (i.e. R. value). The thin layer chromatography separation diagram is shown in Figure A.1. ?
1--Fried vegetable oil sample,
2--Non-polar component,
3--Polar component;
--Unfried vegetable oil sample.
Figure A1 Thin layer chromatography separation diagram
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