1 Scope
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.
Contents
Foreword I
1 Scope
2 Terms and Definition
3 Equipments and Materials
4 Culture Mediums and Reagents
5 Examination Procedure
6 Operation Procedure
6.1 Sample Liquification
6.2 Primary Fermentation Test
6.3 Duplicate Fermentation Test
6.4 Coliforms Most Probable Number (MPN) Report
7 Examination Procedure
8 Operation Procedure
8.1 Sample Liquification
8.2 Plate Enumeration
8.3 Selection of Plate Colony Count
8.4 Verification Test
8.5 Report of Coliforms Plate Enumeration
Annex A (Normative) Culture Mediums and Reagents
A.1 Lauryl Sulfate Tryptose (LST) Broth
A.2 Brilliantgreen Lactose Bile (BGLB) Broth
A.3 Violet Red Bile Agar (VRBA)
A.4 Phosphate Buffer
A.5 Aseptic Physiological Saline
A.6 1 mol/L NaOH
A.7 1 mol/LhCl
Annex B (Normative) Coliforms Most Probable Number (MPN) Search List
B.1 Coliforms Most Probable Number (MPN) Search List
