Overview
ISO 13722:2017 specifies a standardized colony-count technique for the enumeration of viable Brochothrix spp. in the food chain. Originally focused on meat and meat products, the method is also applicable to other foods for human consumption, animal feed, environmental samples in food/feed production and handling, and primary production samples. The standard defines the principle, culture media (STAA), incubation conditions, confirmation tests and reporting format for reliable Brochothrix spp. counts.
Key topics and technical requirements
- Principle: Surface plating (spread plate) of test sample or decimal dilutions onto streptomycin sulfate/thallium acetate agar (STAA), incubation and colony confirmation.
- Inoculation: Transfer 0.1 ml of test sample or initial suspension to each plate and spread evenly; duplicate plates recommended for single suspensions.
- Incubation: Invert plates and incubate 22 °C to 25 °C for 48 h ± 4 h.
- Colony selection and counting: Count characteristic shiny, off‑white, round colonies ≥ 1 mm on plates containing 10–150 colonies; calculate results as CFU per gram or millilitre.
- Confirmation tests: Perform oxidase test (Brochothrix spp. are oxidase‑negative) and catalase test (Brochothrix spp. are catalase‑positive). Select five colonies per plate for confirmation.
- Media and safety notes: The STAA medium formulation is given in the annex; cycloheximide (actidione) has been omitted because of toxicity. Culture media performance testing follows ISO 11133.
- Performance: Validation data from an NMKL collaborative study are included; reported repeatability and reproducibility standard deviations were ~0.13 and 0.22 cfu/g, respectively.
Applications
- Routine food microbiology testing and quality control in meat processing and ready‑to‑eat products where Brochothrix (notably Br. thermosphacta) impacts shelf life and spoilage.
- Environmental monitoring in production and handling areas within food and feed facilities.
- Regulatory and laboratory confirmation testing, research on spoilage organisms, and comparative studies of microbial loads at different production stages.
Who should use this standard
- Food and feed testing laboratories, quality assurance teams in meat and seafood industries, regulatory authorities, and microbiologists conducting shelf‑life or spoilage investigations.
Related standards
Keywords: ISO 13722:2017, Brochothrix spp., Brochothrix thermosphacta, colony-count technique, STAA, food microbiology, enumeration, meat products, ISO standard.
