ISO 2171:2023

Overview

ISO 2171:2023 specifies an analytical method for determining ash yield by incineration in cereals, pulses and their milled products intended for human consumption. The standard covers whole grains, flours, semolinas, bran and high‑bran products, mixed cereal flours, cereal by‑products (e.g., wheat gluten, maize grits, broken rice kernels) and pulse flours. It does not apply to starches and starch derivatives, animal feeding stuffs or seeds.

Key SEO terms: ISO 2171:2023, ash yield, incineration, cereals, pulses, ash determination, milled products, laboratory method.

Key topics and technical requirements

• Principle: Incinerate a representative test portion until organic matter is completely combusted and weigh the inorganic residue (ash).
• Scope & exclusions: Explicit product list and exclusions (see ISO 3593, ISO 5984).
• Incineration temperatures: Two regimes are specified:
  • 900 ± 25 °C (recommended for flour and some products) - platinum‑rhodium dishes preferred; test portion ~3.9–4.1 g; 1 h (flour) to 1–1.5 h (other products).
  • 550 ± 10 °C (recommended for products containing salts and many milled or by‑products) - quartz or silica dishes; test portion ~4.9–5.1 g; 4 h minimum.
• Apparatus & reagents: electrically heated muffle furnace, analytical balance (0.01 mg), platinum‑rhodium or quartz ashing dishes, hydrochloric acid cleaning, desiccant (P2O5 or silica gel), ethanol for ignition at 550 °C.
• Sample preparation: Grinding and representative splitting; moisture must be determined beforehand per ISO 712, ISO 6540 (maize) or ISO 24557 (pulses) or validated NIR methods (ISO 12099).
• Procedure details: dish conditioning, pre‑ashing/ignition, ashing, cooling in desiccator and weighing. Hygroscopic nature of ash and optional vitrification at 900 °C are addressed.
• Quality metrics: repeatability, reproducibility, critical difference and uncertainty are defined and supported by interlaboratory data.

Applications and users

ISO 2171:2023 is intended for:

• Food testing and quality control laboratories performing compositional analysis of cereals and pulses
• Grain mills and flour producers monitoring ash content for grading and process control
• Food manufacturers and ingredient suppliers verifying raw material specifications
• Regulatory bodies and auditors assessing compliance with food standards
• Research institutions studying cereal/pulse composition and processing effects

Practical benefits include consistent ash yield results, improved comparability between laboratories, and guidance on appropriate sample handling and furnace conditions.

Related standards

• ISO 712, ISO 6540, ISO 24557 (moisture determination)
• ISO 12099 (NIR performance)
• ISO 3593 (starches - excluded)
• ISO 5984 (animal feeding stuffs - excluded)
• ISO 24333 (sampling guidance)

For laboratories and food industry professionals, ISO 2171:2023 provides a robust, internationally harmonized method for ash determination essential to product specification, grading and quality assurance.