Overview
EN ISO 11747:2012 - Rice: Determination of rice kernel resistance to extrusion after cooking specifies a laboratory method to measure the force required to push cooked, milled rice kernels (parboiled or non‑parboiled) through a perforated plate. The test quantifies rice kernel resistance to extrusion, a useful indicator of cooked rice texture and processing behavior for quality control, product development and comparative assessment of rice lots.
Key topics and technical requirements
- Scope: Applies to milled rice (parboiled or not) after cooking under the standardised conditions given in the method.
- Principle: Measure force required to extrude cooked rice through a perforated plate using a dynamometer; report mean force per area.
- Sample and cooking: Typical preparation uses two beakers per test, each with 20 g rice and 38 ml deionized water; cooking by steam (boiling water below the perforated plate) for 20 min, rest 10 min, then cool to room temperature ~1 h.
- Apparatus essentials: dynamometer with at least 50 kg loading cell, extrusion/parallelepiped cell (hole area 7.5 cm2), perforated plate (3 mm thick, 6.0 mm holes, 7.0 mm pitch), piston and data acquisition (≥5 samples/s). Movement speed: 10 cm/min.
- Measurement and calculation: Record continuous force during extrusion; calculate mean force from the plateau for six portions and divide by the parallelepiped hole area. Report result in kg/cm² to two decimal places.
- Precision: Repeatability limits and reproducibility limits are provided separately for non‑parboiled and parboiled milled rice (e.g., repeatability r ≈ 0.056 kg/cm² non‑parboiled; reproducibility R ≈ 0.107 kg/cm² non‑parboiled).
- Reporting: Include sample identification, sampling method, test details, any deviations and the measured results.
Applications and practical value
- Quality control in rice milling and processing plants to monitor cooked texture and consistency.
- Product development and formulation (e.g., new rice varieties, parboiling processes).
- Comparative testing for incoming raw materials or finished goods.
- Research labs studying cooking behavior, texture, and process parameters affecting rice quality.
Who should use this standard
- Food quality laboratories, cereal and rice testing labs
- Rice millers and processors, product developers, food scientists
- Regulatory and standards bodies assessing rice product conformity
Related standards
- ISO 712 - Determination of moisture content (reference method used in sample preparation)
- ISO 7301 - Rice - Specification (terms and definitions)
- ISO 24333 - Rice sampling (recommended sampling methods)
Keywords: ISO 11747:2012, rice kernel resistance to extrusion, extrusion after cooking, milled rice testing, rice quality testing, dynamometer extrusion test.