Overview - ISO 24557:2024 (Pulses moisture content, air‑oven method)
ISO 24557:2024 specifies a routine reference method for determining the moisture content of pulses using an air‑oven drying technique. Applicable to chickpeas, lentils, peas, lupinus and all classes of beans (except soybeans), this second edition replaces ISO 24557:2009 and aligns apparatus and procedures with related cereal moisture standards to simplify laboratory routine testing.
Key topics and technical requirements
- Scope and principle: Moisture content is measured as the percentage loss of mass after controlled oven drying (air‑oven method).
- Apparatus: Requires a non‑moisture‑absorbing laboratory mill, a constant‑temperature gravity or mechanical convection oven, moisture dishes or glass dishes, drying trays, an airtight desiccator and an analytical balance.
- Critical parameters:
- Oven temperature: 131.5 °C ± 1.5 °C (oven must recover temperature quickly after loading).
- Drying time: 90 minutes after the oven regains set temperature.
- Test portion: Typically 5–8 g per moisture dish; preconditioning portions ~50 g.
- Balance accuracy: ±0.001 g (readable to at least 0.0001 g).
- Particle size and grinding: Laboratory mill must produce defined particle characteristics and avoid heat/moisture exchange during grinding.
- Preconditioning: Two options - preferred short oven preconditioning (e.g., 15 min at 130–133 °C) or extended air drying (about 48 h) to bring sample moisture into the 9–13% range before grinding.
- Procedure and calculations: Two single determinations per laboratory sample; use arithmetic mean (rounded to two decimals). Formulas are provided to calculate mass loss with or without preconditioning.
- Precision: Repeatability limit r = 0.20% and reproducibility limit R = 0.44% (from interlaboratory testing).
Applications - who uses ISO 24557
- Analytical testing laboratories conducting routine moisture determinations for pulses.
- Grain and pulse processors monitoring drying, storage and handling conditions.
- Quality control & assurance teams verifying conformity to contract specifications and market standards.
- Regulatory bodies and inspection agencies for trade, grading and food safety surveillance.
- Research institutions evaluating moisture effects on storage stability and product quality.
Related standards
- ISO 24333 - recommended sampling for cereals and pulses
- ISO 6540 and ISO 712‑1 - moisture determination methods for corn and cereals (aligned apparatus/procedures)
- ISO 24557:2009 - previous edition (superseded)
Keywords: ISO 24557, pulses moisture content, air‑oven method, moisture determination, chickpeas lentils peas beans, laboratory moisture testing.