Livsmedelsmikrobiologi

This document specifies a method for the enumeration of the characteristic microorganisms Lactobacillus delbrueckii subsp. bulgaricus (in short: L. bulgaricus) and Streptococcus thermophilus (in short: S. thermophilus) by means of the colony-count technique. The method is applicable to yoghurts (for the definition see CXS 243‑2003). The colony-count technique (pour plates) is suitable for, but not limited to, the enumeration of L. bulgaricus and S. thermophilus in test samples with a minimum of 10 colonies counted on a plate. This corresponds to a level of the characteristic microorganisms L. bulgaricus and S. thermophilus that is expected to be higher than 100 cfu/g. The colony-count technique (spread plates) is suitable for, but not limited to, the enumeration of L. bulgaricus and S. thermophilus in test samples with a minimum of 10 colonies counted on a plate. This corresponds to a level of the characteristic microorganisms L. bulgaricus and S. thermophilus that is expected to be higher than 1 000 cfu/g.

This document specifies minimum requirements of performance characteristics for the detection and quantification of nucleic acid sequences (DNA or RNA) by PCR-based assays.

The PCR-based assays specified in this document do not include culturing and nucleic acid extraction stages.

NOTE ISO 22174:2024 [5], clause 13, states that this document specifies the performance characteristics for PCR-based methods. To differentiate from complete methods, which are evaluated according to validation standards such as the ISO 16140 series, the term "PCR-based assay" is used in this document.

This document applies to the detection and/or quantification of nucleic acids of microorganisms (bacteria, yeasts, moulds, viruses and protozoan parasites) associated with:

products intended for human consumption;

products for feeding animals;

environmental samples in the area of food and feed production and handling;

samples from the primary production stage.

This document, or parts of it, is also applicable to other fields of PCR diagnostics based on a case-by-case evaluation.

This document does not apply to sequencing methods or isothermal amplification method