GB/T 5009.159-2003 Determination of reduced ascorbic acid in foods

This standard specifies the spectrophotometric method for ascorbic acid in foods. This standard applies to the determination of reduced ascorbic acid in various foods. This standard does not apply to the determination of dehydrogenated ascorbic acid. GB/T 5009.159-2003 Determination of reduced ascorbic acid in foods GB/T5009.159-2003 Standard download decompression password: www.bzxz.net

TCS 67. G40
National Standard of the People's Republic of China
GB/T 5009.159-2003
Determining reduced-form ascorbic acid in foods
Determining reduced-form ascorbic acid in foods2003-08-11Promulgated
Ministry of Health of the People's Republic of China
National Standards Administration of Standardization of the People's Republic of China
2004-01-01Implementation
Appendix A of this standard is an informative appendix
GD/T 5009.159--2003
This standard was issued by the Ministry of Health of the People's Republic of China and is under the jurisdiction of the Ministry of Health of the People's Republic of China. The responsible drafting unit of this standard is the Health and Epidemic Prevention Station of Hebei Province, and the co-drafting units are: Hebei Provincial Health and Epidemic Prevention Station, Tianjin Food Hygiene Inspection Institute and Gulin Epidemic Prevention Station. The main drafters of this standard. Zhang Wenbo, Li Xinchai, Han Huixin, Xia Yinguo, Qing. 329
GB/T 5009.159—2003
The current national standard CB/T12S92—19904 Determination of total ascorbic acid in vegetables, fruits and their products (fluorescence method and 2,-dinitromethamine method) determines ascorbic acid by oxidative dehydrogenation, but does not determine ascorbic acid by catalysis. Moreover, it is limited to the test group of dried fruits, and the operation is very difficult. It is even more unsuitable for the determination of samples such as non-nutritional foods and white foods. Therefore, a standard test method for the determination of ascorbic acid in food was developed. This method has the characteristics of high sensitivity, good accuracy, simple operation, rapidity and wide application. It is suitable for the determination of ascorbic acid in various foods. Determination of reduced ascorbic acid in food. This standard specifies the spectrophotometric method of ascorbic acid in food. This standard is suitable for the determination of reduced ascorbic acid in food. This standard is not suitable for the determination of desaturated ascorbic acid. 2 Principle
GB/F5009.159-2603
In acetic acid solution, ascorbic acid reacts with solid B to generate a colorless ascorbic acid-2-hydroxybutyryl lactone. The absorbance is measured at 42 μm. Compare with the standard series: 3 Test
3. Add 11.6 μL of acetic acid solution (2 mol/s) and dilute to 100 mL with water. 3.2 Acetic acid drop (0.5 mul/1.), absorb 2.9 ml of acetic acid, dilute to 20 mL with water 3.3 Ethylene glycol disodium acetate (0.25 ml/L) weigh 9.3 ethylamine disodium acetate CmHN, QN, 21 l: put into water, heat to dissolve, then cool to 10. 3.4 Strong white precipitate bzxz.net
3.4.1 Ethylene glycol solution (20 g/1): weigh 22.0 g zinc ethylene glycol [Z (CHCOO), ·2HO], add 3 mL of glacial acetic acid to water, and dilute to 100 mL
3.4.2 Iodine solution (106 g/L): weigh 10. Ferrocyanide [K, Fe (CN>, -3H02, add water to dissolve to m
3.5 Color developer 3. Anti-ascorbic acid standard (2.0/L): Weigh 0.200g ascorbic acid, dissolve it in 20ml (2ml/L) and transfer it to a 10ml standard volumetric flask, dilute it with water to the mark, and add water to the mark. Each milliliter of this solution is equivalent to 2.0g ascorbic acid (store in a refrigerator at ℃ for 2 days). 3.7 Anti-ascorbic acid standard: Use boiling liquid (C.19/L). Use a tube to accurately draw 5.0n ascorbic acid standard (2.0/L) into a CCmL standard container, nl acetic acid solution (2ml/L). 4.1 Spectrophotometer. 4.2 Crusher. 4.3 Centrifugal precipitator. 4.4 10 μm glass colorimetric tube: E Analysis steps 5.1 Preparation of sample 5.1.1 Quality control 5.1.1.1 Liquid sample, sample with scurvy content below 0.2%, can be directly sampled and measured after being homogenized: Sample with scurvy content above 33% can be sampled and measured after being homogenized. 5.1.1.2 For water-soluble solid test, weigh 1.0~5g accurately to 0.001g (including ascorbic acid below 1.2g/kg) into milk, add 5mL acetic acid (2mol/L) to dissolve, transfer to 100ml brown volumetric bottle, add water to dilute to scale, 5.1.1.3 Water content: weigh 20.0g-50.0g of sample into a grinder, add double amount of acetic acid solution (2mol/L) to make a homogenate. Weigh 100~20.0g (including ascorbic acid below 0.2g/kg) into a 100mL brown volumetric bottle, add 5ml acetic acid (2mol/L), stir with a sieve, and mix. Filter with paper, and set aside. Samples that are not easy to pass can be centrifuged by centrifuge: the supernatant is used for determination.
5.1.2 Egg-forming food (milk powder, milk powder, feed, dehydrated food, etc.). Mix the sample and weigh 5.0~10.0g accurately to 0.5g. Use a pipette to transfer 5.0L~10.0L of the sample into a 10mL brown container. Add 10mL of acetic acid solution (2mL/L), zinc acetate solution (22U/L) and potassium ferrocyanide solution (106R/L) to 7.5ml each. Add water to the scale. Mix well, transfer all the sieve into a centrifuge tube, centrifuge at 3°C/min for 10min, and the supernatant is used for determination. At the same time, take the same amount of acetic acid solution, zinc acetate solution and ferrocyanide solution and make a reagent blank test according to the same method. 5.2 Preparation of standard curve
Precision pipette C.5.1.0, 2, 0, 4, 0.5, 0.8, 1.0, 1.5, 2.01ml. Ascorbic acid standard using box (equivalent to ascorbic acid 0: 10.U, 20, J, 40, U, 60, 0.$0, 0, 100, 0.150, 0.200.Cg). Place them in 10ml colorimetric camp respectively, add 0.3ml Z disodium diaminetetraacetic acid solution (0.25mol/L), 0.5ml acetic acid solution (n, 5mnl/T.), 1.25ml. Fast blue disc R drop reduction (2g/J.), add water to dilute the sample to the scale, mix with a spoon). After leaving at room temperature (2%~25℃) for 20min, store in 1cm colorimetric medium, take 4% as reference, collect light at wavelength 420nm, and draw standard curve with absorbance of each point. 5.3 Test sample determination
5.3.1 Determination of non-protein test sample: collect 0.5mL~5.5mL (about equivalent to ascorbic acid 2 (0.25mol/L)) of the sample solution prepared according to 5.1.1 in colorimetric medium, add 3mL of ethylenediamine disodium acetylcholine solution (0.25mol/L) and proceed according to the law. Select absorbance from the standard curve to check the ascorbic acid content. 5.3.2, protein Shake the white sample: Pipette the test solution prepared in 5.1.2 (equivalent to less than 200% of anti-hypertensive aldehyde) and an equal amount of blank solution (0.5mL~5mL). Place each in a 1mL colorimetric tube. Add 1.5mL of disodium ethylenediaminetetraacetic acid (0.25mol/L), 1.0mL of acetic acid (0.5ml/L), 1.25mL of solid solution (<2g/L), and dilute with water until Scale, mix, room temperature <20℃~25.) After setting at 31rmil: move into 1cm room, use reagent blank as reference, measure absorbance at wavelength 42unm, and find out the ascorbic acid content on the sample absorbance curve. 6 Calculation of results
Calculate according to the following formula.
X——Concentration of ascorbic acid in the sample, unit is gram per hundred gram (gram per hundred milligram mg/10og (mg/lOmL) cConcentration of ascorbic acid in the sample solution, unit is microgram (g) - sample mass (volume) unit is gram (ml (rL) ): V: Total volume of the sample solution, unit is liter (); V: Volume of the solution taken during the measurement, unit is milliliter (mJ), 7 Density
The absolute value of two independent measurement results obtained under repeatability conditions shall not exceed 10% of the arithmetic mean. 332
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