Determination of the Aerobic Colony Count in Foods

HPB Method MFHPB-18
October 2001

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1. APPLICATION

This method is applicable to the enumeration of viable aerobic bacteria (psychrophilic, mesophilic and/or thermophilic bacteria) in foods, to determine compliance with the requirements of Sections 4 and 7 of the Food and Drugs Act. Where an Official Method for a food is specified, that method shall be followed. This revised method replaces MFHPB-18, dated April 1998.

2. PRINCIPLE

The Aerobic Colony Count (ACC) estimates the number of viable aerobic bacteria per g or mL of product. A portion of the product is mixed with a specified agar medium and incubated under specific conditions of time and temperature. It is assumed that each viable aerobic bacterium will multiply under these conditions and give rise to a visible colony which can be counted.

3. DEFINITION OF TERMS

See Appendix A of Volume 2.

Psychrophilic bacteria: an organism which grows optimally at or below 15^oC, which has an upper limit for growth at ca. 20^oC, and which has a lower limit of growth of 0^oC or lower.

Mesophilic bacteria: an organism whose optimim growth temperature lies within a range generally accepted as ca. 20 - 45^oC.

Thermophilic bacteria: an organism whose optimimum growth temperature is > 45^oC. See MFHPB-01.

4. COLLECTION OF SAMPLES

See Appendix B of Volume 2.