ISO 24333:2009

Overview

ISO 24333:2009 - "Cereals and cereal products - Sampling" defines standardized procedures for taking representative samples of cereals and cereal products for quality assessment and condition monitoring. The standard covers both dynamic (flowing) and static sampling, by manual or mechanical means, and applies to tests for heterogeneously distributed contaminants, homogeneously distributed quality parameters, insect detection and assessment of GMO lots (but not for detecting adventitious GM material in non‑GM products). It does not apply to seed grain.

Key topics and technical requirements

• Sampling stages: take a defined number of increments → form an aggregate sample → homogenize → subdivide into laboratory sample(s).
• Increment and sample size: ISO specifies minimum numbers and masses (see standard tables). In general, laboratory samples for contaminant analysis range from 1 kg to 10 kg; other analyses typically require at least 1 kg (3 kg for trial milling). One laboratory sample is required per lot or sub‑lot up to 1 500 t (e.g., a 6 000 t lot needs at least four lab samples).
• Flowing vs static sampling: when possible, sample while product is flowing so each part of the lot has equal probability of being sampled; static sampling requires regular, depth‑distributed increments (grid methods for deep stocks).
• Equipment: choose equipment appropriate to product and lot size; mechanical devices for flowing grain, manual probes for shallow static stock (up to ~2 m), mechanical probes up to ~2.5 m if they do not cause segregation, and suction sampling for greater depths. Annexes provide examples of mechanical sampling and dividing devices.
• Integrity and handling: keep equipment clean, prevent cross‑contamination, seal increments if sampling is prolonged, label and package samples correctly, and maintain chain of custody.
• Arbitration and safety: joint sampling by buyer/seller or agreed third party is recommended for disputes; follow hygiene and safety rules during sampling.

Applications

ISO 24333:2009 is practical for:

• Incoming/outgoing quality control in grain elevators, mills, and feed plants
• Regulatory monitoring for contaminants (mycotoxins, pesticides, heavy metals)
• Commercial transactions and arbitration involving large grain lots
• Pest (insect) presence assessments in stored grain
• Sampling GMO lots for quality and condition assessment (not for adventitious GM detection in non‑GM)

Who should use this standard

• Grain elevator and silo operators
• Mill and cereal processors
• Quality assurance and laboratory managers
• Commodity inspectors, traders and auditors
• Regulatory agencies and testing laboratories

Related standards

• ISO 6644 and ISO 13690 (superseded by ISO 24333)
• ISO/TR 29263 (referenced for sample mass ranges)
• ISTA rules (for seed grain sampling)