Overview
ISO 520:2010 specifies a standardized laboratory method for the determination of the mass of 1 000 grains of cereals and pulses. The method applies to all cereal and pulse species except seed lots intended for sowing purposes. ISO 520:2010 provides a repeatable procedure for sample preparation, counting, weighing and expression of results - enabling consistent quality control, trading and reporting across the grain supply chain.
Key topics and technical requirements
- Scope and exclusions: Applies to cereals and pulses; excludes seed lots for sowing.
- Principle: Separate whole grains from a representative test portion, weigh the whole grains, count them and convert the mean mass to the basis of 1 000 grains.
- Test portion: Typically take by division ~500 grains (for straw cereals ~30 g) and perform duplicate tests.
- Counting and weighing:
- Grain counting: photoelectric counter or hand count.
- Balance: readable to 0.001 g; weigh whole grains to the nearest 0.01 g.
- Moisture correction: To report mass on a dry matter basis, determine moisture content of whole grains using ISO 712 (cereals) or ISO 24557 (pulses) and apply the specified correction.
- Expression of results:
- Below 10 g → two decimal places
- 10–100 g → one decimal place
- Above 100 g → whole number
- Special sample handling:
- Separate and count decorticated vs non-decorticated grains.
- Twin oat grains are counted as two separate grains.
- Precision and uncertainty:
- Repeatability limit (r) and reproducibility limit (R) are provided from interlaboratory studies (example: r ≈ 1.3 g, R ≈ 2.3 g for 1 000-grain masses in the 29.8–48.2 g range).
- Expanded uncertainty and critical difference guidance included for comparing measurements.
Applications and who uses it
ISO 520:2010 is used by:
- Grain quality control laboratories and testing facilities
- Milling and feed industries for process control
- Grain traders and commodity inspectors for grading and contract compliance
- Food processors and storage operators for inventory valuation and specification checks
- Regulatory bodies and certification schemes requiring standardized measurement methods
Practical uses include grading, contract verification, varietal characterization (non-sowing lots), quality assurance and supply-chain traceability.
Related standards
- ISO 712 - Cereals: determination of moisture content (reference method)
- ISO 24557 - Pulses: moisture content by air-oven method
- ISO 5725 (parts 3 & 6) - Accuracy (trueness and precision) used for interlaboratory precision statistics
Keywords: ISO 520:2010, mass of 1 000 grains, cereals and pulses, grain weight determination, moisture correction, repeatability, reproducibility, grain quality testing.
