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GB 5413.34-2010 PDF English


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GB 5413.34-2010: PDF in English

GB 5413.34-2010 National food safety standard - Determination of acidity in milk and milk products National Standards of People's Republic of China National Food Safety Standard Determination of acidity of milk and milk products National food safety standard Determination of acidity in milk and milk products People's Republic of China Ministry of Health issued Issued on. 2010-03-26 2010-06-01 implementation Foreword The standard method is given in the first two methods. Benchmarking is equivalent to the International Dairy Federation standard IDF 86. 1978 Dried milk- Determination of titratable acisity (reference method); conventional method is equivalent to the International Dairy Federation standard IDF 81.19 Dried milk- Determination of titratable acidity (routine method); a reference method for the arbitration law. 5009.46-2003 Determination of acidity "analysis of hygienic standard of milk and milk products" This standard replaces GB/T , GB/T 5416-85 "Cream test methods" Determination of acidity, GB 5425-85 "industrial casein test method", GB/T 5409-85 "milk test methods" The milk freshness test and GB/T 5413.28-1997 "Milk powder Determination of titratable acidity." This standard replaces the standards previously issued as follows. --GB/T 5409-85; --GB/T 5413.28-1997; --GB/T 5416-85; --GB 5425-85; --GB 5009.46-1985, GB/T 5009.46-1996, GB/T 5009.46-2003. National Food Safety Standard Determination of acidity of milk and milk products 1 Scope This standard specifies the milk, pasteurized milk, sterilized milk, raw milk, fermented milk, condensed milk, butter and casein determination of acidity. This standard is the first method for the determination of milk acidity; second method is suitable for pasteurized milk, sterilized milk, raw milk, fermented milk, condensed milk, Determination of butter and casein acidity. 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. Determination of first normal acidity of milk Benchmarking Principle 3 In 100 mL of dry matter and 12% of reconstituted milk to a pH of 0.1 mol/L NaOH volume consumed 8.3, calculated to determine its acidity. 4 Reagents and materials Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions tertiary water. 4.1 standard solution of sodium hydroxide (NaOH). 0.1000 mol/L. 4.2 nitrogen. 5. Apparatus 5.1 Balance. a sense of the amount of 1 mg. 5.2 Buret. Subdivision of 0.1 mL, accurate to 0.05 mL. 5.3 pH meter. with a glass electrode and a suitable reference electrode. 5.4 magnetic stirrer. Step 6 Analysis 6.1 Preparation of the sample The samples were all moved into about twice the volume of the sample in a clean, dry container (with closures), the container tightly closed immediately and repeatedly rotating vibrator Dang, the sample was mixed thoroughly. During this operation, the sample should avoid exposure to the air. 6.2 Determination 6.2.1 Weigh 4 g sample (accurate to 0.01 g) in a conical flask. 6.2.2 Take 96 mL of water about 20 ℃ with a graduated cylinder, the sample recovery, stirred and then allowed to stand for 20 min. 6.2.3 burette dropping sodium hydroxide solution to the conical flask (4.1) until the pH reached 8.3. Titration process, always with a magnetic stir Stirrer was added while stirring to the Erlenmeyer flask purged with nitrogen, a solution to prevent the absorption of carbon dioxide in the air. The entire process should be titrated within 1 min carry out. Recording milliliters of sodium hydroxide solution used to the nearest 0.05 mL, into the formula (1) calculations. Conventional method Principle 7 Phenolphthalein as an indicator, cobalt sulfate as a reference color, with 0.1 mol/L sodium hydroxide standard solution titration 100 mL of dry matter of 12% The reconstituted milk to pink consumed volume was calculated to determine its acidity. 8 Reagents and materials Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions tertiary water. 8.1 standard sodium hydroxide solution. Same as 4.1. 8.2 Reference solution. 3g heptahydrate cobalt sulfate (CoSO4 • 7H2O) was dissolved in water and dilute to 100 mL. 8.3 phenolphthalein indicator solution. Weigh 0.5 g phenolphthalein dissolved in 75 mL volume fraction of 95% ethanol and 20 mL of water, then drop Sodium hydroxide solution (8.1) until slightly pink, then add water volume to 100 mL. 9 instruments and equipment 9.1 Analysis of balance. a sense of the amount of 1 mg. 9.2 Buret. Subdivision of 0.1 mL, accurate to 0.05 mL. 10 analysis steps 10.1 Preparation of samples with 6.1. 10.2 Determination 10.2.1 said sample is taken and dissolved with 6.2.1,6.2.2. 10.2.2 to which was added 2.0 mL Erlenmeyer flask a reference solution (8.2), turning it slightly to make it mixed to obtain the standard color. Such as To determine if multiple similar products, this standard solution can be used throughout the determination process, but no longer than 2 h. 10.2.3 second only to the Erlenmeyer flask was added 2.0 mL of phenolphthalein indicator solution (8.3), turning it slightly to mix. Second only to the burette Conical flask was added dropwise a solution of sodium hydroxide (8.1), was added dropwise while the flask was rotated until color similar to the color of the standard solution and within 5 s Does not go away, the whole titration process should be completed within 45 s. Recording milliliters of sodium hydroxide solution used to the nearest 0.05 mL, into the formula (1) Calculations. 11 analysis results presentation Sample values in acidity (ºT) said, according to the formula (1). 1.0) 1 ( 1 × - × ×× = wm VcX (1) Where. Acidity, the sample unit X1-- degrees (ºT); C1-- standard concentration of sodium hydroxide solution, the unit of moles per liter (mol/L); The milliliters of sodium hydroxide solution used when V1-- titration, in milliliters (mL); m1-- saying that the quality of the samples taken, in grams (g); w - sample moisture content in grams per hundred grams (g/100g); 12--12 g milk quite 100 mL reconstituted milk (skimmed milk powder should be 9, skimmed whey powder should be 7); The molar concentration of sodium hydroxide theoretical definition 0.1-- acidity, expressed in moles per liter (mol/L). The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures. Note. In terms of lactic acid content of the sample represents acidity, the acid content of the sample (g/100g) = T × 0.009. T is the sample of titratable acidity (lactic acid 0.009 Conversion factor, namely 1 mL0.1 mol/L sodium hydroxide standard solution is equivalent to 0.009 g lactic acid. ) 12 Precision Two independent determination results under the absolute difference in repeatability condition must not exceed 1.0 ºT. The second method of measuring milk and other dairy products acidity Principle 13 Phenolphthalein as an indicator solution with 0.1000 mol/L sodium hydroxide standard titration solution of sodium hydroxide solution to the end of the body 100 g sample consumed Product, was calculated to determine the acidity of the sample. 14 Reagents and materials Unless otherwise specified, the reagents used in this method were of analytical grade or above specifications, water GB/T 6682 provisions tertiary water. 14.1 neutral ethanol - ether mixture. taking an equal volume of ethanol, adding ether after mixing 3 drops of phenolphthalein indicator solution, sodium hydroxide solution (4 g/L) drops to reddish. 14.2 sodium hydroxide standard solution. Same as 4.1. 14.3 phenolphthalein indicator solution. Same as 8.3. 15 instruments and equipment 15.1 balance. a sense of the amount of 1 mg. 15.2 titrator. 15.3 Buret. Subdivision of 0.1 mL. 15.4 water bath. 16 analysis steps 16.1 pasteurized milk, sterilized milk, raw milk, fermented milk Weigh 10 g (accurate to 0.001 g) was mixed sample, placed in 150 mL conical flask, add 20 mL freshly boiled and cooled to room temperature Water, and mix with a standard solution of sodium hydroxide (14.2) potentiometric titration to pH 8.3 as the end point; or to dissolve the sample after mixing was added 2.0 mL of phenolphthalein indicator solution (14.3), mix with standard sodium hydroxide solution (14.2) titrated to a reddish color and do not fade within 30 s, Record sodium hydroxide standard titration solution consumed in milliliters, into the formula (2) in the calculation. 16.2 Cream Weigh 10 g (accurate to 0.001 g) was mixed sample, add 30 mL neutral ethanol - ether mixture (14.1), mix the following By 16.1 "by potentiometric titration with standard sodium hydroxide solution to pH 8.3 for the end" operation. Casein 16.3 Weigh 5 g (accurate to 0.001 g) mixing the milled sample in flask, add 50 mL of water at room temperature (18 ℃ ~ 20 ℃ for 4 h ~ 5 h, or in a water bath heated to 45 ℃ and maintained at this temperature for 30 min, plus 50 mL of water, mix, by Dry filter paper. Draw filtrate in 50 mL Erlenmeyer flask with standard sodium hydroxide solution (14.2) as the end point potentiometric titration to pH8.3; Or above 50 mL was added to the filtrate, 2.0 mL of phenolphthalein indicator solution (14.3), mix with standard sodium hydroxide solution (14.2) to the micro titration Red, and do not fade within 30 s, the standard sodium hydroxide solution consumed in ml into the formula (3) is calculated. 16.4 condensed milk Weigh 10 g (accurate to 0.001 g) was mixed sample, placed in 250 mL conical flask, add 60 mL freshly boiled and cooled to room temperature Is dissolved in water, mix, according to the following 16.1 "potentiometric titration with standard sodium hydroxide solution to pH8.3 to end" operation. 17 analysis results presentation Sample values in acidity (ºT) said calculated as follows. 1.0 twenty two 2 × ×× = VcX (2) Where. Acidity, the sample unit X2-- degrees (ºT); C2-- molar concentration of sodium hydroxide standard solution, unit mole per liter (mol/L); V2-- titration standard solution of sodium hydroxide consumption by volume in milliliters (mL); m2-- sample mass, in grams (g); The molar concentration of sodium hydroxide theoretical definition 0.1-- acidity, expressed in moles per liter (mol/L). The arithmetic average of the two independent determination results obtained under repeatability conditions, said the results to three significant figures. 1.0 3 × ××× = Vc X (3) Where. Acidity, the sample unit X3-- degrees (ºT); C3-- molar concentration of sodium hydroxide standard solution, unit mole per liter (mol/L); V3-- titration standard solution of sodium hydroxide consumption by volume in milliliters (mL); m3-- sample mass, in grams (g); The molar concentration of sodium hydroxide theoretical definition 0.1-- acidity, expressed in moles per liter (mol/L); 2-- sample dilution. The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures. 18 Precision Two independent determination results under the absolute difference in repeatability condition must not exceed 1.0 ºT. ......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.