ISO/NP 13559

Microbiology of the food chain — Horizontal method for the enumeration of contaminating microorganisms — Colony count at 30 °C by the surface plating technique

Scope

This document specifies a horizontal method for the enumeration of contaminating microorganisms that are able to grow and form colonies on the surface of sugar free agar (SFA) after aerobic incubation at 30 °C. Contaminating microorganisms can be enumerated in food and feed cultures in their pure form (e.g. probiotics and starter cultures) or when these cultures have been added to food and feed products (e.g. fermented products or products containing probiotics).
This document is applicable to:
— products intended for human consumption;
— products for feeding animals.
This document is applicable to matrices where bacterial cultures have been intentionally added. However, some food and feed cultures will be able to grow and form colonies on the surface of SFA after aerobic incubation at 30 °C (for example, Enterococcus lactis and Heyndrickxia coagulans). Equally some matrices may contain a high level of carbohydrates that, if the neat sample (liquid matrices) or the initial suspension is plated on SFA, the non-target microorganisms are able to grow and form colonies on the surface of SFA. Therefore, the suitability of this method is determined following the procedure described in Annex C.
This document is not applicable when non-target microorganisms are able to grow and form colonies in the surface of SFA.