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GB 5413.31-2013 English PDF (GB5413.31-2013)

GB 5413.31-2013 English PDF (GB5413.31-2013)

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GB 5413.31-2013: National Food Safety Standard Determination of urease in infant foods and dairy products

This standard specifies the determination methods for urease in infant foods and dairy products. This standard applies to qualitative detection of urease in infant food and dairy urease.
GB/T 5413.31-2013
GB
NATIONAL STANDARD
OF THE PEOPLE REPUBLIC OF CHINA
National standard on food safety
Infant food and dairy products ?€?
Determination of urease
ISSUED ON. NOVEMBER 29, 2013
IMPLEMENTED ON. JUNE 01, 2014
Issued by. National Family Planning Commission
Table of contents
Foreword ... 3
1 Scope ... 4
2 Principles ... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 6
5 Analysis steps ... 6
6 Presentation of analysis results ... 6
7 Detection limit ... 7
Foreword
This standard replaces GB/T 5413.31-1997 Milk powder and formula foods for infant and young children - Qualitative detection of urease.
As compared with GB/T 5413.31-1997, the main changes of this standard are as follows.
- MODIFY the standard name;
- ADD the storage conditions for urea solution;
- ADD the storage conditions for Nessler's reagent;
- ADD the time limit for determination results.
National standard on food safety
Food and dairy products for infant and young children
- Determination of urease
1 Scope
This standard specifies the determination methods for urease in infant foods and dairy products.
This standard applies to qualitative detection of urease in infant food and dairy urease.
2 Principles
Under the appropriate pH and temperature conditions, urease will catalyze the urea to convert into ammonium carbonate. Ammonium carbonate will, under the alkaline conditions, generate ammonium hydroxide, which will react with the potassium iodide double salt in the Nessler's reagent to produce brown double- mercury ammonium iodide.
3 Reagents and materials
Note. Unless otherwise stated, the reagents used in this standard are of analytical pure AND the water is grade III water as specified in GB/T 6682. 3.1 Reagents
3.1.1 Urea (H2NCONH2).
3.1.2 Sodium tungstate (Na2WO4?€?2H2O).
3.1.3 Potassium sodium tartrate (C4H4O6KNa?€?4H2O).
3.1.4 Sulfuric acid (H2SO4).
3.1.5 Disodium hydrogen phosphate (Na2HPO4).
3.1.6 Potassium dihydrogen phosphate (KH2PO4).

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