ISO 5529:2007

Overview

ISO 5529:2007 - "Wheat - Determination of the sedimentation index - Zeleny test" defines a laboratory method (the Zeleny sedimentation test) for assessing a key quality attribute of wheat (Triticum aestivum L.). The test measures the sedimentation index - the volume (mL) of sediment formed when a precisely prepared test flour is suspended in an acid–alcohol medium - and is used to help predict the baking strength of flour produced from the wheat.

Key topics and technical requirements

• Scope: Applicable only to Triticum aestivum L. wheat for prediction of flour baking strength.
• Principle: Protein swelling in an acid medium produces a sediment whose volume correlates with gluten quality and baking performance.
• Reagents: Includes lactic acid (stock solution prepared by refluxing and titration to a defined molarity), propan-2-ol (isopropanol), bromophenol blue dye and standard titrants/indicators. The standard specifies reagent grades and storage/use windows (e.g., test solution use 48 h to 15 days after preparation).
• Apparatus: Typical lab equipment plus specified items such as test mills (see Annex A), a 150 µm sieve (ISO 565), 100 mL graduated flat-bottom cylinders, a timed cylinder shaker, pipettes (ISO 648), and analytical balances.
• Test flour preparation: Grinding and sieving conditions are specified (particle size <150 µm; extracted mass ~10% of original grain) to ensure reproducible results.
• Procedure: Weigh 3.20 g test portions, add dye, perform staged shaking with the test solution, allow a fixed standing time (300 s ± 5 s), then record sediment volume to the nearest mL.
• Result expression and quality control: The sedimentation index is reported as whole millilitres. Rules for averaging, repeat testing when results exceed the repeatability limit, and how to handle multiple determinations are given.
• Precision: Repeatability, reproducibility and critical difference metrics are provided (interlaboratory data summarized in Annex B).

Applications and users

ISO 5529:2007 is used by:

• Cereal quality and milling laboratories for routine quality control and specification testing.
• Grain traders and breeders to help screen wheat lots for end-use (baking) suitability.
• Food technologists and research labs assessing protein quality, dough/baking performance correlations.
• Regulatory and standards bodies when harmonized analytical methods are required.

Practical value: the Zeleny test is quick, relatively low-cost and widely accepted as a predictor of flour baking strength, supporting purchasing decisions, variety selection and process control.

Related standards

• ISO 13690 (sampling recommendations)
• ISO 565 (test sieves)
• ISO 648 (pipettes)
• ISO 3696 (water for laboratories)
• ISO 712 (moisture determination)

Keywords: ISO 5529:2007, Zeleny test, sedimentation index, wheat quality, Triticum aestivum, baking strength, test flour, lactic acid, propan-2-ol, repeatability, reproducibility.