ISO 16140-5:2020

Overview

ISO 16140-5:2020 - "Microbiology of the food chain - Method validation - Part 5" - specifies a protocol for factorial interlaboratory validation for non‑proprietary methods. The standard defines general principles and technical procedures based on orthogonal, factorial experimental designs to validate microbiological methods used to detect or quantify microorganisms in food, feed, environmental samples (production and handling) and primary production. It is particularly applicable to bacteria and fungi, with the possibility to extend to other microorganisms or metabolites on a case‑by‑case basis.

Key technical topics and requirements

• Factorial interlaboratory design: Uses orthogonal, factorial studies where multiple factors (e.g., technician, culture medium, temperature) are varied simultaneously to characterize method performance while reducing the number of participating laboratories.
• Minimum laboratories: The protocol enables validation with a reduced number of laboratories (a minimum of four), addressing situations where the larger interlaboratory studies required by ISO 16140‑2 are impractical.
• Scope of methods: Applicable only to non‑proprietary methods that are fully specified (including tolerances and media specifications) and already optimized.
• Validation pathways:
  • Validation against a reference method (qualitative and quantitative methods).
  • Validation without a reference method (quantitative methods only). Qualitative methods require a reference method in this document.
• Study stages:
  • In‑house validation prior to interlaboratory study.
  • Interlaboratory validation with specified measurement protocols, factor selection, and experimental designs (paired/unpaired options).
• Data analysis and interpretation: Includes calculations for summary data, precision estimates, analysis of factorial effects (including evaluation relative to RLOD - relative limit of detection), and development of accuracy profiles for quantitative methods.
• Supporting material: Informative annexes provide suggested factors and levels and worked examples for quantitative and qualitative studies.

Practical applications

• Accelerates method validation where time, resources, or specialized techniques limit the number of participating labs.
• Validates culture‑based and other microbiological detection/quantification methods used in:
  • Food safety testing and compliance
  • Feed analysis
  • Environmental monitoring in food/feed production facilities
  • Primary production sampling
• Helps demonstrate method robustness across typical laboratory variables (operator, media, incubation conditions).

Who would use this standard

• Microbiologists, method developers, and validation scientists
• Food and feed testing laboratories and quality control teams
• Reference laboratories and regulatory bodies evaluating non‑proprietary methods
• Standards committees and technical working groups

Related standards

• ISO 16140 series: Part 1 (vocabulary), Part 2 (validation vs reference methods), Part 3 (verification), Part 4 (single‑lab validation), Part 6 (confirmation/typing)
• ISO 17468 (development and validation rules for standardized methods)

Keywords: ISO 16140-5, method validation, factorial interlaboratory validation, microbiology of the food chain, non‑proprietary methods, quantitative methods, qualitative methods, orthogonal factorial study.