ISO 4832:2006

ISO 4832:2006 gives general guidelines for the enumeration of coliforms. It is applicable to products intended for human consumption and for the feeding of animals, and environmental samples in the area of food production and food handling, by means of the technique of counting colonies after incubation on a solid medium at 30 °C or at 37 °C.
This technique is recommended when the number of colonies sought is expected to be more than 100 per millilitre or per gram of the test sample.