GB 5009.237-2016 PDF English
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GB 5009.237-2016: National Food Safety Standard -- Determination of pH value of food
---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB5009.237-2016GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National standard for food safety - Determination of pH value in food Issued on: AUGUST 31, 2016 Implemented on: MARCH 1, 2017 Issued by. National Health and Family Planning Commission of the People’s Republic of China 3. No action is required - Full-copy of this standard will be automatically & immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
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... 9Foreword
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 food1 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. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
