Overview
ISO 771:2021 specifies a standardized laboratory method for the determination of moisture and volatile matter in oilseed meals (meals obtained by oil extraction by pressure and/or solvent). The method uses oven drying to constant mass and expresses results as grams per 100 g (g/100 g). ISO 771:2021 replaces the 1977 edition and includes updated precision data from a recent interlaboratory trial.
Key topics and requirements
- Scope: Applies to oilseed meals (rapeseed, sunflower, soya, etc.) produced by pressing and/or solvent extraction.
- Principle: Grind sample to 1 mm particle size, dry a test portion at (103 ± 2) °C at atmospheric pressure until practically constant mass is reached.
- Sample preparation: Follow ISO 5502 for test-sample preparation; representative sampling recommended (see ISO 5500).
- Apparatus and materials:
- Analytical balance: readability 0.0001 g (precision 0.001 g)
- Mechanical mill and 1 mm sieve
- Flat-bottomed metal or glass vessels (spread test portion to ~0.2 g/cm²)
- Electric oven with good ventilation and thermostatic control
- Desiccator with efficient desiccant
- Procedure highlights:
- Carry out two determinations per sample
- Use about 5 g test portion; weigh vessel + sample before and after drying
- Initial drying: 2 h after oven stabilizes at target temperature, then reweigh; continue 1 h drying cycles until successive weighings differ ≤ 0.005 g
- Calculate moisture/volatile matter w = (m1 − m2) / (m0 − m2) × 100 (use mean of two reps when repeatability satisfied); report to one decimal place
- Precision:
- Repeatability (r): for mean < 4.0% → r = 0.20%; for mean > 4.0% → r = 0.018x + 0.13
- Reproducibility (R): for mean < 4.0% → R = 0.40%; for mean > 4.0% → R = 0.033x + 0.27
- Precision data based on an 11-laboratory collaborative trial (Annex A/B)
Applications and users
ISO 771:2021 is used for:
- Quality control in feed and oilseed processing plants
- Contract testing and trade verification of oilseed meals
- Regulatory and compliance testing for feed/food safety and labeling
- Laboratory method standardization in research and interlaboratory studies
Primary users:
- Analytical laboratories, QC teams, feed manufacturers, commodity traders, certification bodies, and research institutes.
Related standards
Keywords: ISO 771:2021, oilseed meals, moisture determination, volatile matter, oven drying method, repeatability, reproducibility, laboratory method, feed quality control.
