Overview
EN ISO 6647-2:2020 - "Rice - Determination of amylose content - Part 2" describes a spectrophotometric routine method without a defatting procedure, using calibration from rice standards. Published by CEN/ISO, this part specifies two simplified, routine procedures (hot dispersion - Method A, and cold dispersion - Method B) for determining the amylose mass fraction of milled, non‑parboiled rice. The methods are intended for samples with an amylose mass fraction > 5% and are widely used in routine food testing and quality control laboratories.
Key topics and requirements
- Scope & applicability
- For milled, non‑parboiled rice with amylose > 5%.
- Simplified sample prep commonly used in routine labs; defatting step omitted (unlike the reference method ISO 6647‑1).
- Principle
- Rice is milled to a fine flour, dispersed in sodium hydroxide, an aliquot is reacted with iodine and the absorbance of the amylose‑iodine complex is measured (typically at 720 nm, also 620 nm or 680 nm may be used).
- Amylose content is read from a calibration graph prepared using rice standards whose amylose content was determined by the reference method.
- Two dispersion procedures
- Method A (hot dispersion) - uses 1 mol/L NaOH and a boiling water bath.
- Method B (cold dispersion) - uses 2 mol/L NaOH and high‑speed magnetic stirring.
- Reagents & apparatus
- Ethanol (95 %), NaOH at specified concentrations, 1 mol/L acetic acid, fresh iodine/potassium iodide solution.
- Grinder (to pass 150–180 µm), spectrophotometer (1 cm cells), volumetric flasks, pipettes, analytical balance.
- Calibration & performance
- Calibration solutions are prepared from rice samples used as standards; calibration and statistical evaluation follow ISO guidance.
- The document includes precision data (repeatability, reproducibility, interlaboratory test results) and reporting requirements.
Applications & who uses it
- Routine quality control in rice milling and processing plants.
- Food‑testing and analytical laboratories performing compositional analysis.
- Rice breeders and research institutions assessing varietal amylose levels.
- Regulatory bodies, import/export inspection and product specification verification.
- Useful for product labeling, nutritional profiling, and process optimization where amylose content affects cooking/texture.
Related standards
- ISO 6647‑1:2020 - Reference spectrophotometric method with defatting.
- ISO 712 - Determination of moisture content for cereals.
- ISO 7301 - Rice specification.
- ISO 8466‑1 - Calibration and statistical evaluation of analytical methods.
This standard is essential for laboratories seeking a validated, standardized spectrophotometric routine method to measure rice amylose content efficiently and consistently without a defatting step.
