Organisms associated with food spoilage are generally recognised by their predominance in numbers or as a percentage of the microbiological flora of the food. The total process of isolation which encompasses sample preparation, choice of culture medium and incubation conditions (time, temperature, atmosphere) may not totally reflect the conditions in the food being examined. Thus colonies that develop on a total count medium may not be wholly representative of the organisms responsible for spoilage of the food.

Conventional bacteriological techniques used in the examination for spoilage organisms include performance of a “total” colony count, isolation of known spoilage organisms using selective media and identification of suspect colonies.