This document specifies a horizontal method for enumeration of microorganisms that are able to grow and form colonies in a solid medium after aerobic incubation at 30 °C.
The method described in this document is applicable to:
— products intended for human consumption;
— products intended for feeding animals (including pets);
— environmental samples in the area of food and feed production and handling;
— all samples from the primary production stage.
This technique is suitable for, but not limited to, the enumeration of microorganisms in test samples with a minimum of 10 colonies counted on a plate. This corresponds to a level of contamination that is expected to be higher than 10 cfu/ml for liquid samples or higher than 100 cfu/g for solid samples.
This technique is especially suitable for:
— products that require a reliable count when a low limit of quantification is specified,
— products expected to contain spreading colonies that can obscure colonies of other organisms, e.g. milk and milk products likely to contain spreading Bacillus species;
— products expected to contain bacteria that are sensitive to oxygen, e.g. some lactic acid bacteria that develop during shelf life or modified atmosphere storage.
This horizontal method was originally developed for the examination of samples belonging to the food chain. Because of the large variety of products in the food chain, it is possible that this horizontal method is not appropriate in every detail for all products. Nevertheless, it is expected that the required modifications are minimized so that they do not result in a significant deviation from this horizontal method.
Based on the information available at the time of publication of this document, the suitability of this method for the examination of certain fermented food and animal feeds is considered to be limited and other media or incubation conditions can be more appropriate. However, this method can still be applied to such products even though it is possible that the predominant microorganisms in those products are not detected effectively.
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