ISO 4833-1:2013 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 is applicable to: a) products intended for human consumption and for animal feed; b) environmental samples in the area of food and feed production and handling.

ISO 4833-1:2013 is applicable to: 1) products that require a reliable count when a low limit of detection is specified (below 10²/g or 10²/ml for liquid samples or below 10³/g for solid samples); 2) products expected to contain spreading colonies that obscure colonies of other organisms, e.g. milk and milk products likely to contain spreading Bacillus spp.

The applicability of ISO 4833-1:2013 to the examination of certain fermented food and animal feeds is limited and other media or incubation conditions can be more appropriate. However, this method can be applied to such products even though it is possible that the predominant microorganisms in those products are not detected effectively.

For some matrices, the method specified in ISO 4833-1:2013 can give different results to those obtained using the method specified in ISO 4833-2.