Overview
ISO 7889:2026 - Yoghurt - Enumeration of characteristic microorganisms - Colony-count technique, specifies the internationally recognized method for the enumeration of the main yoghurt cultures, Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) and Streptococcus thermophilus (S. thermophilus), in yoghurt using the colony-count technique. Issued jointly by ISO and the International Dairy Federation (IDF), this standard ensures consistent, reliable testing for yoghurt producers, laboratories, and regulators. Accurate enumeration of these characteristic microorganisms is essential for monitoring product quality, authenticity, and compliance with food industry standards.
Key Topics
- Enumeration Method: The standard details the colony-count technique, including both pour plate and spread plate methods, for counting viable colonies of L. bulgaricus and S. thermophilus in yoghurt samples.
- Applicability: Suitable for all types of yoghurt as defined in CXS 243-2003, where the microorganism levels are above 100 cfu/g for pour plates and above 1,000 cfu/g for spread plates.
- Microorganism Identification: Focuses on the detection of L. bulgaricus on MRS 5.4 agar (anaerobic incubation) and S. thermophilus on M17-S agar (microaerobic incubation).
- Sample Preparation: Standardizes the preparation of yoghurt test samples, dilutions, inoculation, incubation, and enumeration steps to ensure repeatability and reproducibility.
- Quality Assurance: Recommends appropriate controls, validation procedures, and documentation following ISO 7218 and ISO 11133 for laboratory reliability.
Applications
ISO 7889:2026 is crucial for a range of stakeholders in the food and dairy sectors:
- Yoghurt Manufacturers: By implementing this method, producers can verify that cultured dairy products meet required microbial standards, ensuring consistent flavour, texture, safety, and shelf-life.
- Quality Control Laboratories: Enables standardized and accredited microbiological testing of dairy products, supporting product compliance and food safety audits.
- Regulatory Authorities: Provides a harmonized reference method for enforcement, market surveillance, and verification of claims regarding yogurt cultures.
- Research & Product Development: Facilitates scientific assessment of fermentation processes and optimization of starter cultures, supporting innovation in probiotic and functional dairy products.
The colony-count technique outlined in ISO 7889:2026 supports traceability and transparency in the dairy supply chain, from raw material to finished product, meeting both regulatory and consumer expectations for yoghurt quality and authenticity.
Related Standards
To ensure best practices and regulatory compliance, ISO 7889:2026 should be used in conjunction with:
- ISO 6887-1 & ISO 6887-5 - Preparation of test samples and dilutions for microbiological examination of food and milk products.
- ISO 7218 - General guidance for microbiological examinations, including equipment, safety, and reporting.
- ISO 11133 - Preparation, production, storage, and performance testing of culture media.
- CXS 243-2003 - Codex standard for fermented milks, including yoghurt definitions and specifications.
- ISO 9232 - Identification of L. bulgaricus and S. thermophilus.
For laboratories seeking accreditation or producers targeting international markets, use of ISO 7889:2026 within this framework of dairy testing standards ensures reliable yoghurt microbiology results and supports global recognition of product quality.
Keywords: ISO 7889, yoghurt testing, L. bulgaricus enumeration, S. thermophilus enumeration, colony-count technique, dairy microbiology standard, yoghurt quality control, international standards, fermented milk testing, ISO standards for dairy.
