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GB 5413.34-2010: National food safety standard -- Determination of acidity in milk and milk products
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 g...