ISO 21569:2005

Overview

ISO 21569:2005 - Foodstuffs: Methods of analysis for the detection of genetically modified organisms and derived products - Qualitative nucleic acid based methods - defines standardized procedures to qualitatively detect GMOs by analysing nucleic acids extracted from food matrices. The standard focuses on PCR-based amplification methods and provides guidelines, minimum requirements and performance criteria to ensure comparable, accurate and reproducible results across laboratories. Annexes A–D give concrete method examples (target-taxon-specific, screening, construct-specific and event-specific).

Key topics and technical requirements

• Scope and principle
  • Qualitative detection gives a clear presence/absence answer for target DNA sequences relative to controls and method detection limits.
  • Main emphasis on conventional and real-time PCR methods.
• Sample and nucleic acid quality
  • Extracts must be free of PCR inhibitors; integrity and amplifiability influence detection limits, especially in processed foods.
• PCR design and reagents
  • Recommended primer characteristics: 18–30 nucleotides, optimal annealing ~60 °C, balanced GC content; product size chosen to match DNA degradation (e.g., 60–150 bp for highly degraded material).
  • Use of hot-start PCR is recommended to improve specificity.
  • Note: dUTP use can interfere with subsequent restriction analyses.
• Performance and validation
  • Performance criteria and method-specific values are provided in the annexes.
  • Optimized PCR should detect ~100 copies of template DNA within 40 cycles under ideal conditions.
  • Primer validation: (1) theoretical (sequence similarity search, e.g., BLAST), and (2) experimental specificity testing.
• Detection and confirmation
  • PCR products may be detected by gel electrophoresis or real-time PCR; identity confirmation by restriction analysis, hybridization or DNA sequencing.
• Quality assurance
  • Inclusion of appropriate positive/negative and inhibition controls, method reporting requirements and inter-laboratory comparability measures.

Practical applications and users

• Who uses it:
  • Food and feed testing laboratories, regulatory agencies, contract analytical labs, environmental monitoring groups, seed and ingredient suppliers, and academic researchers.
• Practical uses:
  • Regulatory compliance and labeling verification for GMO content.
  • Routine surveillance and screening of raw materials and processed foods.
  • Method development and validation for laboratories implementing qualitative GMO detection.
  • Event- or construct-specific identification for traceability and enforcement.

Related standards

• ISO 21571 - Nucleic acid extraction (complementary procedures)
• ISO 21570 - Quantitative nucleic acid based methods
• ISO 21568 - Sampling for GMO analysis
• ISO 24276 - General requirements and definitions for nucleic-acid based GMO methods

Keywords: ISO 21569:2005, GMO detection, qualitative PCR, nucleic acid based methods, food analysis, primer validation, event-specific, construct-specific, screening methods.