Overview
EN ISO 6540:2021 (ISO 6540:2021) specifies standardized methods for the determination of moisture content in maize, covering both milled grains and whole grains. Published by CEN/ISO, the standard defines a reference (absolute) method for milled maize, groats, grits and maize flour (Clause 4) and a routine whole-grain method (Clause 5). It replaces the 2010 edition and includes informative annexes on the absolute method, interlaboratory test results and fidelity data.
Key topics and technical requirements
- Two validated methods:
- Reference (absolute) method - intended as the laboratory benchmark for moisture determination; requires specialized equipment and experienced personnel (see Clause 4 and Annex A).
- Routine whole-grain method - simplified approach for whole maize that avoids grinding and pre-drying (see Clause 5).
- Scope of products: whole maize, ground whole maize, groats, grits and maize flour.
- Sampling and sample preparation: standardized procedures for representative sampling, grinding (where required) and handling to account for maize-specific challenges (high moisture, large grain size).
- Measurement procedure elements: defined test portions, drying procedures, weighing and calculation of moisture content (see Clauses 4.4–4.6 and 5.4–5.5).
- Performance and quality metrics: precision data including repeatability, reproducibility, interlaboratory test results and uncertainty assessment are provided (Clause 4.7 and Annex B).
- Known bias: the routine whole-grain method exhibits a positive bias (~0.30 % mass fraction) relative to the reference method; therefore it is not suitable for expert reports or for calibration/checking of humidity meters (see Table B.3).
Applications and users
- Who uses EN ISO 6540:2021
- Grain testing laboratories and quality control labs
- Grain processors, millers and food manufacturers
- Commodity traders and storage operators monitoring moisture for storage stability
- Regulatory bodies and conformity assessment organizations
- Instrument manufacturers (moisture meters) referencing standard methods
- Practical uses
- Routine QC moisture checks on incoming/outgoing maize shipments (use whole-grain method for throughput)
- Official laboratory reporting and calibration using the reference/absolute method
- Establishing moisture specifications for storage, processing and sale
Related standards
- ISO 712 (general methods for cereals) - referenced as context for cereal moisture methods
- CEN/TC 338 publications on cereals and cereal products
For anyone involved in maize moisture analysis, EN ISO 6540:2021 is the authoritative reference for method selection, performance expectations and reporting practices. Keywords: EN ISO 6540:2021, maize moisture content, moisture determination, reference method, routine method, whole grains, milled grains.
