ISO 7889:2026

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[7]). 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.