Foreword
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This standard replaces GB 4789.26-2013 Food microbiological examination - Examination of commercial sterilization.
The following main changes have been made with respect to GB 4789.26-2013:
——The definitions of “commercial sterilization” and “acidified food” are added;
——The procedures for examination of commercial sterilization in food production are added;
——The requirement of re-weighing after incubation and the method for examining the tightness of canned food are deleted;
——The applicable scope of the standard, and the definitions of low acid food and acid food as well as the corresponding examination steps are modified.
National food safety standard - Food microbiological examination - Examination of commercial sterilization
1 Scope
This standard specifies the procedures, steps, requirements for result judgment and reporting in connection with the examination of commercial sterilization of food.
This standard is applicable to the examination of commercial sterilization of food.
2 Terms and definitions
2.1
commercial sterilization
state in which the food is moderately sterilized by heating and does not contain either pathogenic or non-pathogenic microorganisms that can reproduce at normal temperatures
2.2
low acid food
food with equilibrium pH greater than 4.6 and water activity greater than 0.85 after sterilization
2.3
acid food
food that has not been acidified but (or the broth) has an equilibrium pH of 4.6 or less and water activity greater than 0.85 after sterilization. Tomato products with pH less than 4.7 are acid foods
2.4
acidified food
food with water activity greater than 0.85 and equilibrium pH equal to or less than 4.6 after being acidified by adding acidity regulator or using other acidification methods
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3 Equipment and materials
In addition to the conventional sterilization and culture equipment and materials in microbiological laboratory, other equipment is as follows.
3.1 Refrigerator: 2°C–5°C;
3.2 Constant temperature incubator: 30°C±1°C, 36°C±1°C, 55°C±1°C;
3.3 Constant-temperature culture room: 30°C±2°C, 36°C±2°C, 55°C±2°C;
3.4 Constant temperature water bath: 55°C±1°C;
3.5 Homogenizer, with sterile homogeneous bags, homogeneous cups or mortars.
3.6 Potentiometric pH meter: With an accuracy of pH 0.01;
3.7 Microscope objective: 10X–100X;
3.8 Can punch or container opener;
3.9 Anaerobic incubator (jar).
4 Culture media and reagents
4.1 Culture media: See Annex A.
4.2 Crystal violet staining solution: See Annex A, A.8.
4.3 Gram staining solution: See Annex A, A.9.
4.4 Sterilized saline water: See Annex A, A.10.
4.5 Xylene.
4.6 Ethanol solution containing 4% iodine: 4 g of iodine is dissolved in 100 mL of 70% ethanol solution.
4.7 75% ethanol solution: Pipette 75 mL of anhydrous ethanol and 25 mL of water, and mix them well for later use.
4.8 70% ethanol solution: Pipette 70 mL of anhydrous ethanol and 30 mL of water, and mix them well for later use.
Foreword i
1 Scope
2 Terms and definitions
3 Equipment and materials
4 Culture media and reagents
5 Examination of commercial sterilization in food circulation
6 Examination of commercial sterilization in food production
Annex A Media and reagents
Annex B Inoculated culture and analysis of anomaly
