GB 22031-2010 English PDF

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GB 22031-2010: National food safety standard -- Determination of added citrate content in cheese and processed cheese products
Status: Valid

GB 22031: Historical versions

Standard ID	USD	BUY PDF	Lead-Days	Standard Title (Description)	Status
GB 22031-2010	229	Add to Cart	3 days	National food safety standard -- Determination of added citrate content in cheese and processed cheese products	Valid
GB/T 22031-2008	399	Add to Cart	3 days	Determination of added citrate content in cheese and processed cheese products by Enzyme -- Colorimetric method	Obsolete

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GB 22255   GB/T 22246   GB/T 21928   GB/T 45701   GB 28050   GB/T 22035   

Basic data

Standard ID: GB 22031-2010 (GB22031-2010)
Description (Translated English): National food safety standard -- Determination of added citrate content in cheese and processed cheese products
Sector / Industry: National Standard
Classification of Chinese Standard: C53;X16
Classification of International Standard: 67.100.30
Word Count Estimation: 10,188
Date of Issue: 2010-03-26
Date of Implementation: 2010-06-01
Older Standard (superseded by this standard): GB/T 22031-2008
Regulation (derived from): Circular of the Ministry of Health (2010)7
Issuing agency(ies): Ministry of Health of the People's Republic of China
Summary: This Chinese standard specifies the cheese and processed cheese products added citrate content (as citric acid) measurement method. This standard applies to cheese and processed cheese products added citrate content.

GB 22031-2010: National food safety standard -- Determination of added citrate content in cheese and processed cheese products

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
National food safety standard.Determination of added citrate content in cheese and processed cheese products National Standards of People's Republic of China People's Republic of China Ministry of Health issued Issued on. 2010-03-26 2010-06-01 implementation National Food Safety Standard Cheese and processed cheese products of citrate added Determine National food safety standard Determination of added citrate content in cheese and processed cheese products

Foreword

This standard replaces GB/T 22031-2008 "cheese and processed cheese products of added citrate content determination of enzyme - colorimetric method." The Standard Appendix A, Appendix B normative appendix. This standard replaces the standards previously issued as follows. --GB/T 22031-2008. National Food Safety Standard Determination of cheese and processed cheese products added citrate

1 Scope

This standard specifies the cheese and processed cheese products of added citrate content (citric acid meter) measurement method. This standard applies to the determination of citrate content in cheese and processed cheese products added to.

2 Normative references

The standard file referenced in the application of this standard is essential. For dated references, only the edition date of the note Apply to this standard. For undated references, the latest edition (including any amendments) applies to this standard. Principle 3 Determination of the total sample of citrate, deducting the amount of raw materials into the sample citrate (0.04 times the lactose conversion), namely Samples of added citrate content. Citrate, citric acid count. Step 4 Analysis Determination of the total content of the samples and citrate calculated according to Appendix A of the regulations. Determination and lactose content in the sample is calculated in accordance with Appendix B of the regulations.

5 expression analysis

Samples at levels of added citrate (1) is calculated. wa = wc-rwi (1) Where. wa-- sample added citrate content in terms of citric acid, the mass fraction (%) represented; wc-- total content of citric acid in the sample, in units of mass fraction (%); wi - lactose content in the sample, in units of mass fraction (%); r - the ratio of raw milk or whey and lactose content of citric acid content (citric acid/lactose) (r = 0.04). The arithmetic mean of two under the same condition of independent determination results indicated that the results of reservations to two decimal places.

6 precision

Two independent determination results under the absolute difference in repeatability condition must not exceed 10% of the arithmetic mean.

Appendix A

(Normative) Cheese and processed cheese products of enzymatic assay of citrate content A.1 Scope This standard applies to enzymatic assay cheese and processed cheese products citrate content. A.2 Principle Citrate lyase (CL) will citrate into oxaloacetate and acetate, malate dehydrogenase (MDH) and lactate dehydrogenase Catalase (LDH) catalyzed decarboxylation of oxaloacetate and decarboxylation of malonic at reduced nicotinamide adenine dinucleotide (of NADH) in the presence of Keto acid salt, were transformed into L- L- malic acid and lactic acid. NADH is oxidized in the reaction it became NAD. Determination of the sample solution at 340 nm In NADH absorbance difference calculation citrate content in the sample. A.3 Reagents and materials Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions of secondary water. A.3.1 trichloroacetic acid solution (200 g/L). Weigh 20 g of trichloroacetic acid (CCl3COOH) was dissolved in water, mix, and set the volume to 100 mL. A.3.2 sodium hydroxide solution (200 g/L). Weigh 20 g of sodium hydroxide (NaOH), dissolved in water transferred to 100 mL volumetric flask, Volume. Mixed thoroughly. A.3.3 sodium hydroxide solution (40 g/L). Weigh 4 g of sodium hydroxide (NaOH), dissolved in water transferred to 100 mL volumetric flask, Yung. Mixed thoroughly. A.3.4 sodium hydroxide solution (4 g/L). Weigh 0.4 g of sodium hydroxide (NaOH), dissolved in water transferred to 100 mL volumetric flask, Yung. Mixed thoroughly. A.3.5 zinc chloride solution (0.8 g/L). Weigh 0.8 g of zinc chloride (ZnCl2), dissolved in water transferred to 1000 mL volumetric flask, constant volume. Mixed thoroughly. A.3.6 buffer (pH 7.8). Weigh 7.13 g glycylglycine (H2NCH2CONHCH2CO2H), was dissolved in 70 mL of water, transferred to a 100 mL volumetric flask. Adjusted with sodium hydroxide solution (A.3.2) pH 7.8, was added 10 mL of zinc chloride solution (A.3.5) and dilute to 100 mL. Mixed thoroughly. Stored in a refrigerator 0 ℃ ~ 4 ℃, the solution can save around. A.3.7 sodium bicarbonate solution (4.0 g/L). Weigh 4.0 g of sodium bicarbonate (NaHCO3), dissolved in water transferred to 1000 mL volumetric flask, Volume. Mixed thoroughly. A.3.8 nicotinamide adenine dinucleotide (NADH) solution. take 50 mg of nicotinamide adenine dinucleotide disodium salt (C21H27N7O14P2Na2) and 100 mg of sodium bicarbonate (NaHCO3), was dissolved in 10 mL of water. A.3.9 ammonium sulfate solution (422 g/L). Weigh 42.2 g of ammonium sulfate [(NH4) 2SO4], dissolved in water transferred to 100 mL volumetric flask, Yung. Mixed thoroughly. A.3.10 malate dehydrogenase (MDH) and lactate dehydrogenase (LDH) suspension. ammonium sulfate solution (A.3.9) are dissolved Apple Dehydrogenase (pig heart, EC 1.1.1.37) and lactate dehydrogenase (rabbit, EC 1.1.1.27), so malate dehydrogenase (MDH) activity Not less than 600 IU/mL and lactate dehydrogenase activity is not less than 1400 IU/mL. Slowly stir into suspension after storage at 0 ℃ ~ 4 ℃ refrigerator And the solution can be kept for one year. A.3.11 citrate lyase (CL) solution. 0 ℃ dissolved in water with citrate lyase (Enterobacter aerogenes, EC 4.1.3.6), make lemon Citric acid lyase activity of not less than 40 IU/mL. Slowly stir into suspension after storage at 0 ℃ ~ 4 ℃ refrigerator, this solution can be Paul Deposit one week; at -20 ℃ refrigerator, you can save around. A.3.12 citric acid standard solution (160 μg/mL). Weigh 175 mg of citric acid monohydrate (C6H8O7 · H2O), dissolved in water was transferred to a 1000 mL volumetric flask, constant volume. Mixed thoroughly. A.4 instruments and equipment A.4.1 Balance. a sense of the amount of 0.1 mg. A.4.2 pH meter. accuracy of 0.1. A.4.3 grinder. A.4.4 stoppered graduated colorimetric tube. 10 mL, dividing the value of 0.1 mL. A.4.5 medium speed filter paper. A.4.6 UV-Vis. 340 nm, 1 cm cuvette. A.4.7 water bath. A.5 Sample preparation A.5.1 cheese Remove shell surface or moldy cheese, the sample representative. With a grinder (A.4.3) The sample was crushed, and mix. A.5.2 cheese products Select a representative sample pulverized with a grinder (A.4.3), and mix. A.6 analysis step A.6.1 Preparation of test solution Weigh 1 g (accurate to 0.0001 g) sample (A.5), was dissolved in 50 mL of hot water (40 ℃ ~ 50 ℃), the entire transferred into 100 mL Flask, cooled to 20 ℃. Then add 10 mL of trichloroacetic acid solution (A.3.1), volume with water, mix well stand for 30 min. use Filter paper (A.4.5) filtered and filtrate was discarded early about 10 mL. Draw 25 mL filtrate in a beaker with sodium hydroxide solution (A.3.3) adjustment filter Solution to pH 4, and then sodium hydroxide solution (A.3.4,) to adjust the pH to 8. The beaker was transferred into a 100 mL volumetric flask, add water Yung. While doing the blank test. A.6.2 Determination A.6.2.1 Drawing standard curve Before using a reagent to room temperature. Imbibe 0.00 mL, 0.50 mL, 1.00 mL, 1.50 mL, 2.00 mL (equivalent to 0.80, 160,200,320μg citric acid) groups citric acid standard solution (A.3.12), were placed in 10 mL colorimetric tube (A.4.4), each added 1.00 mL buffer solution (A.3.6), 0.10 mL NADH solution (A.3.8), 0.02 mL malate dehydrogenase (MDH) and lactate dehydrogenase (LDH) Suspension (A.3.10), shake. Holding 5 min at 20 ℃ ~ 25 ℃ water bath (A.4.7), the water volume to 5.00 mL. One group With a 1 cm cuvette (A.4.6), with air as reference, measured in each colorimetric tube solution absorbance at a wavelength of 340 nm at A0. Another plus for each group Into 0.02 mL of citrate lyase (A.3.11), mixing, holding 10 min at 20 ℃ ~ 25 ℃ water bath (A.4.7), and by 1 cm Cuvette (A.4.6), with air as reference, measured in each colorimetric tube solution absorbance at a wavelength of 340 nm at A10. According to (2) is calculated Absorbance A, citric acid content of the ordinate, the absorbance A is the abscissa, the standard curve. A = A0-A10 (2) Where. A0 - citrate lyase before adding absorbance; A10 - absorbance of water bath 10 min after adding the citrate lyase. Note. If the absorbance decrease over .800, with an aqueous solution of diluted sample and blank test, repeat step A.6.2.1. A.6.2.2 Determination of test solution absorbance With two pipette 2.00 mL of test solution (A.6.1), placed in 10 mL colorimetric tube (A.4.4) in. A.6.2.1 with the following steps in "each plus Into 1.00 mL buffer (A.3.6) standard curve "operation, to identify the corresponding citric acid content on standard curve. At the same time short White test. A.7 expression analysis Citric acid content of the sample according to equation (A.2) calculations. X = 10000 VVm VVc ××× ×× (3) Where. X - citric acid content of the sample, in grams per hundred grams (g/100g); Isolated on c-- standard curve test solution of citric acid content in micrograms (μg); m-- sample mass, in grams (g); V1 - sample deproteinized constant volume after volume, in milliliters (mL); V2 - draw filtrate volume in milliliters (mL); V3 - constant volume filtrate volume in milliliters (mL); V4 - absorb the test solution volume in milliliters (mL). The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures. A.8 Precision Two independent determination results under the absolute difference in repeatability condition must not exceed 10% of the arithmetic mean.

Appendix B

(Normative) Enzymatic determination of cheese and processed cheese lactose content B.1 Scope This standard applies to enzymatic assay cheese and processed cheese products lactose content. B.2 Principle In β- galactosidase (β-GLS) catalyzed hydrolysis of lactose is the D- glucose (G) and D- galactose (GL). Hexokinase (HK) D- phosphorylation of glucose to glucose 6-phosphate is generated (G6P), while adenosine triphosphate (ATP) into adenosine diphosphate (ADP). By glucose-6-phosphate dehydrogenase (G6PDH) catalyzed oxidation of glucose-6-phosphate to glucose 6-phosphate acid (GA6P), while nicotinamide Adenine dinucleotide phosphate (of NADP) is reduced to reduced nicotinamide adenine dinucleotide phosphate (NADPH). At a wavelength of 340 nm Absorbance is proportional to the value of the lactose content of NADPH, compared with standard series quantitation. C12H22O11 (L) H2O β-GLS D-C6H12O6 (G) D-C6H12O6 (GL) D-C6H12O6 (G) ATP HK G6P ADP G6P NADP H2O G6PDH GA6P NADPH H B.3 Reagents and materials Unless otherwise specified, the method used were of analytical grade reagents and water for the two water GB/T 6682 regulations. B.3.1 Standard lactose substance (C12H22O11 · H2O), the purity of ≥99%. B.3.2 potassium ferrocyanide solution (36 g/L). Weigh 3.6 g of potassium ferrocyanide {K4 [Fe (CN) 6] · 3H2O}, dissolved in water, the volume to 100 mL, Mix well. B.3.3 zinc sulfate solution (72 g/L). Weigh 7.2 g zinc sulfate (ZnSO4 · 7H2O), dissolved in water, the volume to 100 mL, and mix. B.3.4 sulfuric acid solution (2 mol/L). Measure 60 mL of sulfuric acid, slowly inject the right amount of water, diluted with water and cooled to room temperature to 1000 L, Mix well. Warning. When diluting concentrated sulfuric acid should be added slowly to the water, and stirred constantly. Otherwise it will cause an explosion. B.3.5 sodium hydroxide solution (200 g/L). Weigh 20.0 g of sodium hydroxide (NaOH), dissolved in water, the volume to 100 mL, and mix. B.3.6 sodium hydroxide solution (4 g/L). Weigh 4.0 g of sodium hydroxide (NaOH), dissolved in water, dilute to 1000 mL, and mix. B.3.7 ammonium sulfate solution (422 g/L). Weigh 42.2 g of ammonium sulfate [(NH4) 2SO4], dissolved in water, the volume to 100 mL, and mix. B.3.8 citrate buffer (pH 6.6). Weigh 2.8 g of sodium citrate (C6H5O7Na3 · 2H2O), 0.042 g citric acid (C6H8O7 · H2O) and 0.635 g of magnesium sulfate heptahydrate (MgSO4 · 7H2O) was dissolved in 40 mL of water, sulfuric acid solution (B.3.4) or hydroxide Sodium solution (B.3.6) adjusting the pH to 6.6 ± 0.1, the water volume to 50 mL, mixing after the placement 0 ℃ ~ 4 ℃ refrigerator storage, save Three months before, using the place to room temperature. B.3.9 triethanolamine (TEA) buffer (pH 7.6). Weigh 14.0 g hydrochloric acid triethanolamine (C6H15NO3 · HCl), 0.25 g seven Over anhydrous magnesium sulfate (MgSO4 · 7H2O), was dissolved with 80 mL of water, adjusting the pH with sodium hydroxide solution (B.3.5) until after 7.6 ± 0.1, dilute to 100 mL, after mixing place 0 ℃ ~ 4 ℃ refrigerator storage, can be kept for two months. B.3.10 NADP -ATP-TEA buffer suspension. 65 mg were taken accurately called nicotinamide adenine dinucleotide phosphate, disodium (C21H26N7O17P3Na2) and 170 mg 5- adenosine triphosphate disodium salt (C10H14N5O13P3Na2), was dissolved in 30 mL of triethanolamine buffer Solution (B.3.9), and after mixing place 0 ℃ ~ 4 ℃ refrigerator storage can be maintained for two weeks before using to room temperature. B.3.11 β- galactosidase - ammonium sulfate [β-GLS- (NH4) 2SO4] suspension (pH about 7.6). The [beta] galactosidase (β-GLS, Escherichia E. coli, EC 3.2.1.23) were dissolved in ammonium sulfate solution (B.3.7), allowing β- galactosidase activity is not less than 60 IU/mL. Slowly stir After the suspension was absorbed into place 0 ℃ ~ 4 ℃ refrigerator, up to 12 months. When using the suspension should be immersed in a container of ice water. B.3.12 hexokinase glucose-6-phosphate dehydrogenase - ammonium sulfate [HK-G6PDH- (NH4) 2SO4] suspension. The hexokinase (HK, yeast Mother, EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (G6PDH, yeast, EC 1.1.1.49) was dissolved ammonium sulfate solution (B.3.7), allowing Hexokinase activity of not less than 280 IU/mL (25 ℃), 6- phosphate dehydrogenase activity is not less than 140 IU/mL (25 ℃). Slowly stir After the suspension was absorbed into place 0 ℃ ~ 4 ℃ refrigerator, up to 12 months. When using the suspension should be immersed in a container of ice water. B.3.13 lactose standard solution (80 μg/mL). learn precisely weighed 87 ℃ bake 2 h to constant weight lactose standard substance (B.3.1) 0.842 g, Dissolved in water and dilute to 100 mL, shake. Imbibe 1.00 mL of the above solution was diluted with water to 100 mL, to obtain a concentration of 80 μg/mL Lactose standard working solution. The solution was placed 0 ℃ ~ 4 ℃ refrigerator, prepared before use. B.4 instruments and equipment B.4.1 balance. a sense of the amount of 0.1 mg. B.4.2 Quantitative filter paper. speed, diameter 15 cm. B.4.3 colorimetric tube. 10 mL, with cover. B.4.4 Spectrophotometer. 340 nm, 1 cm cuvette. B.4.5 Water bath. Can incubated at 20 ℃ ~ 36 ℃. B.5 analysis step B.5.1 Sample Preparation Take a representative sample of at least 200 g, mixed thoroughly, placed in a sealed glass container. B.5.2 Preparation of test solution Accurately weigh 1 g sample into a beaker. With warm water (40 ℃ ~ 50 ℃) was dissolved, with stirring glass rod, the sample is completely transferred to the beaker 100 mL volumetric flask to volume with water and mix. Added 5 mL potassium ferrocyanide solution (B.3.2), 5 mL zinc sulfate solution (B.3.3) and 10 mL NaOH solution (B.3.6), mix well after each addition solution, water volume to 100 mL, mix well stand for 30 min. filter, Abandoned part of the filtrate to the beginning. Draw 5.00 mL filtrate in 100 mL volumetric flask, dilute to 100 mL of water, is the test solution. B.5.3 Draw standard curve Using a micro pipette 0.00,0.20,0.40,0.60,0.80,1.00 mL (equivalent 0,16,32,48,64,80μg lactose) Lactose Standard Standard solution (B.3.13), were placed in a colorimetric tube (B.4.3), each was added 0.20 mL of citrate buffer solution (B.3.8), 0.05 mLβ- Galactosidase - ammonium sulfate suspension (B.3.11), shaken, heated in water bath (B.4.5) in 15 min. After removing added 1.00 mL NADP -ATP-TEA buffer solution (B.3.10), 0.05 mL hexokinase glucose -6- phosphate dehydrogenase - ammonium sulfate suspension (B.3.12), Shake the pan in a water bath (B.4.5) in a constant temperature 60 min. After removing the cooled to room temperature, water volume to 5.00 mL, shake for 5 min. With a 1 cm cuvette (B.4.4), reagent solution lactose content of zero standard solution as reference, measured each colorimetric tube at the wavelength at 340 nm The absorbance of the solution. Lactose content of the ordinate absorbance as the abscissa, the standard curve. B.5.4 Determination of test solution absorbance Imbibe 1.00 mL sample solution (B.5.2) in colorimetric tube (B.4.3) added 0.20 mL citrate buffer solution (B.3.8), 1.00 mL NADP -ATP-TEA buffer solution (B.3.10), 0.05 mL hexokinase glucose-6-phosphate dehydrogenase - ammonium sulfate suspension (B.3.12), shake the pan in a water bath (B.4.5) in a constant temperature 60 min. After removing the cooled to room temperature, water volume to 5.00 mL, shake, Place 5 min, the test solution as the reference solution. Imbibe 1.00 mL sample solution (B.5.2) in colorimetric tube (B.4.3) in. The following press B.5.3 "each added 0.20 mL citrate buffer Solution (B.3.8) placed 5 min "operation, 1 cm cuvette (B.4.4), measured in each colorimetric tube solution at a wavelength of 340 nm with Absorbance, isolated lactose content in the corresponding standard curve. B.6 expression analysis The lactose content of the sample according to the formula (4) calculations. X = 10000 VVm VVc ××× ×× (4) Where. X - the lactose content of the sample, in grams per hundred grams (g/100g); c - the standard curve isolated lactose content of the test solution, in micrograms (μg); m - mass of sample in grams (g); V1 - sample deproteinized constant volume after volume, in milliliters (mL); V2 - draw filtrate volume in milliliters (mL); V3 - constant volume filtrate volume in milliliters (mL); V4 - absorb the test solution volume in milliliters (mL). The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures. B.7 Precision Two independent determination results under the absolute difference in repeatability condition must not exceed 10% of the arithmetic mean. ......

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