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GB 5009.237-2016National Food Safety Standard -- Determination of pH value of food (English PDF)

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Issued by

National Health and Family Planning Commission of the People’s Republic of China 3. No action is required - Fu

Level / Type

National · Mandatory

Issue date

August 31, 2016

Implementation date

March 1, 2017

Scope

GB 5009.237-2016 (National Food Safety Standard -- Determination of pH value of food) is available as an English-translated PDF.

GB 5009.237-2016 — This Standard specifies the methods for determination of pH in meat and meat products, oysters in aquatic products, and canned food.

This Standard is applicable to the pH testing for the homogenized products and the pH non-destructive testing for the slaughtered carcasses and lean meat in meat and meat products, the pH determination for oysters in aquatic products, and the pH determination for canned food.

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Document preview — GB 5009.237-2016

National Standard of the People's Republic of China

Issued by: National Health and Family Planning Commission of the People’s Republic of China 3. No action is required - Fu

Foreword...3
1 Scope...4
2 Principle...4
3 Reagents and materials...4
4 Instruments and equipment...6
5 Analytical procedures...6
6 Expression of the analysis results...9
7 Precision...9

Foreword

This Standard replaces the determination of pH in GB/T 5009.45-2003 Method

for analysis of hygienic standard of fish and other aquatic products, the

determination of pH in GB/T 10786-2006 Analytical methods of canned food,

and GB/T 9695.5-2008 Meat and meat products - Measurement of pH.

Compared with the substituted standards, the major changes in this Standard

are as follows.

— CHANGE the standard name into "National standard for food safety -

Determination of pH value in food"; and

— This Standard integrates the methods for determination of pH in food in

GB/T 5009.45-2003 Method for analysis of hygienic standard of fish and

other aquatic products, GB/T 10786-2006 Analytical methods of canned

food and GB/T 9695.5-2008 Meat and meat products - Measurement of

pH.

National standard for food safety -

Determination of pH value in food

1 Scope

This Standard specifies the methods for determination of pH in meat and meat

products, oysters in aquatic products, and canned food.

This Standard is applicable to the pH testing for the homogenized products

and the pH non-destructive testing for the slaughtered carcasses and lean meat

in meat and meat products, the pH determination for oysters in aquatic products,

and the pH determination for canned food.

2 Principle

A glass electrode is used as a reference electrode, a calomel electrode or a

silver-silver chloride electrode as a reference electrode. When the

concentration of hydrogen ions in the sample or sample solution changes, the

electromotive force between the indicator electrode and the reference electrode

also changes, resulting in a DC potential (that is, potential difference). INPUT

to an A/D converter through a preamplifier, in order to achieve the purpose of

pH measurement.

3 Reagents and materials

Unless otherwise stated, the reagents used in this method are of analytical

grade, and water is the tertiary water specified in GB/T 6682. Water used in the

preparation of buffer solution shall be freshly boiled, or USE nitrogen free of

carbon dioxide to remove carbon dioxide in the water.

3.1 Reagents

3.1.1 Potassium hydrogen phthalate [KHC6H4(COO)2].

3.1.2 Potassium dihydrogen phosphate (KH2PO4).

3.1.3 Disodium (hydrogen) phosphate (Na2HPO4).

3.1.4 Potassium bitartrate (KHC4H4O6).

3.1.5 Disodium citrate (Na2HC6H5O7).

For heterogeneous samples, PROCEED in accordance with Subclause 5.2.4.

5.2.2 Samples (only for meat and meat products)

ADD potassium chloride solution with 10 times the mass of the sample to be

tested to a homogenized sample (SEE Subclause 5.1.1.3). USE a homogenizer

to perform homogenization.

5.2.3 Determination of homogenized samples

TAKE a quantity of the sample that can immerse or embed the electrode.

INSERT the electrode into the sample. ADJUST the temperature compensation

system of the pH meter to the sample temperature. If the pH meter is not

equipped with a temperature compensation system, the temperature of the

sample to be determined shall be kept within the range of 20°C ± 2°C.

DETERMINE by taking the steps suitable for the pH meter in use. After the

reading display is stable, READ the value directly. Accurate to 0.01. PROCEED

in accordance with Subclause 5.2.5.

The same prepared sample shall be determined at least twice.

5.2.4 Determination of heterogeneous samples

USE a knife or pin to punch a hole on the sample, so as not to damage the

composite electrode.

ADJUST the temperature compensation system of the pH meter (4.2) to the

sample temperature. If the pH meter is not equipped with a temperature

compensation system, the temperature of the sample to be determined shall be

kept within the range of 20°C ± 2°C. DETERMINE by taking the steps suitable

for the pH meter in use. After the reading display is stable, READ the value

directly. Accurate to 0.01.

Fresh meat is usually stored between 0°C and 5°C. A pH meter with a

temperature compensation system is required for the determination. REPEAT

the determination at the same point. REPEAT the determination at different

points on the sample, if necessary. The number of determination points

depends on the properties and size of the sample.

The same prepared sample shall be determined at least twice.

5.2.5 Electrode cleaning

USE degreasing cotton dipped with ether and ethanol successively to wipe the

electrodes. RINSE with water eventually. STORE the electrodes as required by

the manufacturer.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 9 pages — is available in the English PDF.

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