Overview
ISO/TS 27265:2026 specifies standardized methods for the enumeration of thermoresistant spores of thermophilic bacteria in heat-processed milk and dried milk products. Developed jointly by ISO and the International Dairy Federation (IDF), this technical specification outlines reliable procedures using a colony-count technique at 55 °C following heat treatment of samples at either 106 °C (30 minutes) or 100 °C (30 minutes). The standard applies to a broad range of heat-processed dairy products, including pasteurized, ultra-high temperature (UHT) processed, and sterilized milk, as well as dried whole milk, skim milk, buttermilk, and whey products. By providing harmonized analytical methods, ISO/TS 27265:2026 supports food safety and product quality across the global dairy sector.
Key Topics
- Thermoresistant Spores: Focuses on spores of thermophilic bacteria capable of surviving high-temperature treatments, which are a key factor in dairy product spoilage and potential public health risks.
- Sample Preparation: Samples undergo defined heat treatments to selectively activate and enumerate thermoresistant spore-forming bacteria.
- Colony-Count Methods: The specification includes both pour-plate and spread-plate techniques using bromocresol purple (BCP) plate count skim milk agar for improved colony visibility.
- Incubation Conditions: Standardized incubation at 55 °C for 48 hours ensures enumeration of thermophilic bacteria.
- Quality Assurance: Emphasizes laboratory best practices and quality control, including the use of control strains and validated culture media.
- Reporting and Repeatability: Detailed requirements for reporting procedures, results, and any deviations, alongside specifications for the repeatability of results.
Applications
- Dairy Quality Control: Essential for manufacturers of pasteurized, UHT, sterilized, and dried milk products to monitor and control the levels of thermophilic spores, reducing spoilage and extending shelf life.
- Regulatory Compliance: Assists dairy laboratories and quality assurance teams in meeting international and national safety and quality requirements.
- Research and Development: Provides a robust method for academic and industrial research focused on improving dairy process hygiene and safety.
- Supply Chain Risk Management: Enables food processors and suppliers to assess and manage microbiological hazards associated with thermophilic spore-formers, ensuring consistent product safety and minimizing economic loss.
- Third-Party Testing Laboratories: Offers standardized protocols ensuring comparability and reliability of test results between different laboratories worldwide.
Related Standards
- ISO 6887-1: Preparation of test samples, initial suspension, and decimal dilutions for microbiological examination of foods.
- ISO 6887-5: Specific rules for the preparation of milk and milk products for microbiological testing.
- ISO 7218: General requirements and guidance for microbiological examinations of the food chain.
- ISO 11133: Preparation, production, storage, and performance testing of culture media for food, animal feed, and water microbiology.
- ISO 707 | IDF 50: Guidance on sampling of milk and milk products.
- ISO 5725-1: General principles and definitions for accuracy (trueness and precision) of measurement methods and results.
- ISO 19036: Estimation of measurement uncertainty for quantitative determinations in the food chain.
By adhering to ISO/TS 27265:2026, dairy sector stakeholders enhance food safety, product consistency, and international trade compliance through reliable detection and enumeration of thermoresistant thermophilic bacterial spores.