Overview
ISO 6639-2:1986 (part of the ISO 6639 series) sets out accepted methods for sampling cereals and pulses to determine hidden insect infestation. It covers general principles, required apparatus, recommended sampling times and places, pre-sampling inspection and lot identification, procedures for sampling bulk grain and grain in bags, preparation of laboratory samples, and packaging, labelling and despatch of samples.
This part is intended for routine use at any level of trade - from producer to consumer - and supports practical decision-making when inspecting grain stores, transport vehicles or stacks of bags.
Key Topics
-
General principles: Sampling schemes aim to maximise practical information; where insect populations are unknown, schemes are pragmatic rather than strictly statistical. Clean, dry sampling equipment and contamination control are emphasised.
-
Apparatus: Examples include automatic samplers or pelican scoops for flowing grain, hand scoops for static surfaces, cylindrical samplers or sample dividers for bags, and woven sample bags resistant to insect attack. Sample bags should be cleaned and may be disinfected (standard notes describe oven treatment) and stored in sealed jars until use.
-
Sampling times and places: Samples may be taken at any point in the distribution chain. It is generally not useful to sample less than three weeks after harvest due to insect life cycles. Sampling during commodity movement (loading/unloading) is often most effective; static storage sampling is more difficult but important for long-term storage.
-
Bulk grain sampling: For flowing grain use equipment that samples across the entire cross-section (automatic sampler or pelican scoop). For static bulks, priority sampling locations are surface zones and shallow depths (surface layers and near ventilation or outlet points) where infestation is likeliest. Surface-layer depth depends on temperature conditions.
-
Sampling grain in bags: Select sample bags by a randomized scheme adapted to stack size; always include corner and top-layer bags where insects commonly concentrate. Use a cylindrical sampler or an appropriate divider to obtain representative increments.
-
Laboratory sample preparation: Combine increments to form a bulk sample unless individual increments are being examined; reduce bulk samples using established reduction methods to obtain a laboratory sample of not less than 1 kg. Pack samples in cleaned sample bags and seal with metal seals to ensure inviolability.
-
Packaging, labelling and despatch: Labels should indicate that samples are for hidden insect infestation analysis and include contractual identifiers. Despatch samples promptly - normally within 48 hours - and protect samples against transit hazards.
Applications
- Routine quality control at storage facilities, terminals and processing plants
- Inspection during trading, shipping and receiving of cereals and pulses
- Forensic or dispute investigations where precise sampling and chain-of-custody are required
- Basis for audit protocols and pest management planning
Related Standards
- ISO 6639-1/3/4 - companion parts covering general principles, reference and rapid methods
- ISO 950 - cereals: sampling (grain)
- ISO 951 - pulses in bags: sampling
- ISO 6644 - automatic sampling by mechanical means
These related standards define specific sampling devices, reduction methods and additional procedural detail that complement ISO 6639-2:1986.
Open preview (PDF)Cereals and pulses — Determination of hidden insect infestation — Part 2: Sampling