This standard specifies the enumeration methods of coliforms in food.
This standard is applicable to the enumeration of coliforms in food.
2 Terms and Definitions
2.1 Coliforms
It refers to the aerobic and anaerobicgram-negative non-spore-bearing bacillus that can ferment lactose, produce acid andgas under a certain cultivation condition.
2.2 Most probable number, MPN
It refers to an indirect enumeration method based on Poisson distribution.
3 Equipments and Materials
Except forgeneral microbe laboratory sterilization and cultivation equipments, other equipments and materials are listed as following:
3.1 Thermostatic incubator: 36℃±1℃.
3.2 Refrigerator: 2℃~5℃
3.3 Thermostatic water bath: 46℃±1℃.
3.4 Scale: sensibility 0.1g.
3.5 Homogenizer.
3.6 Oscillator.
3.7 Sterile straw: 1mL (with 0.01mL scale), 10mL (with 0.1mL scale) or micropipettor and sucker.
3.8 Sterile cone flask: capacity 500mL.
3.9 Sterile culture dish: diameter 90 mm.
3.10 Acidimeter or pH color comparison tube or short-range pH paper.
3.11 Colony counter.
