ISO 21415-4:2006

Overview

ISO 21415-4:2006 - "Wheat and wheat flour - Gluten content - Part 4" specifies a rapid drying method for determining dry gluten from wet gluten obtained according to ISO 21415-1 or ISO 21415-2. The method provides a fast laboratory procedure to quantify gluten content and to determine the moisture content of wet gluten, supporting routine quality control and analytical testing in cereal and flour laboratories.

Key topics and technical requirements

• Scope: Rapid conversion of wet gluten to dry gluten for reporting gluten content (% mass fraction) and wet-gluten moisture.
• Principle: A weighed ball of wet gluten is dried between pre-warmed plates and reweighed; the mass loss yields dry gluten and water content.
• Apparatus:
  • Electrically heated drying plates (anti-adhesion coating), heated by resistance coils to a working temperature of 150 °C to 200 °C (see Annex A).
  • Analytical balance capable of 0.01 g resolution.
• Procedure:
  • Preheat drying plates by running one cycle before testing.
  • Place a weighed ball of wet gluten (most wash solution removed) between plates for 300 s ± 5 s.
  • Reweigh dried gluten and calculate results.
• Calculations:
  • Dry gluten (%) = (mass of dry gluten / mass of original sample used for wet gluten extraction) × 100.
  • Moisture of wet gluten (%) = (mass of wet gluten − mass of dry gluten) / mass of wet gluten × 100.
  • Results are the arithmetic mean of two determinations; dry-matter corrections may be applied using ISO 712 moisture values.
• Precision:
  • Repeatability: absolute differences greater than 0.6 g/100 g occur in not more than 5% of cases.
  • Reproducibility limits depend on how wet gluten was obtained: up to R = 4.1 g/100 g (manual) or R = 2.0 g/100 g (mechanical).

Applications and users

ISO 21415-4:2006 is used by:

• Quality control and analytical laboratories in flour mills, grain elevators and processing plants.
• Food testing and contract laboratories performing gluten content analysis for specification, labelling and trade.
• Breeding and research groups profiling wheat protein traits.
• Regulatory agencies and standards organizations verifying compliance.

Practical uses include routine QC of wheat and wheat flour, batch acceptance testing, process control, and determining wet-gluten moisture for recipe and functional performance assessment.

Related standards

• ISO 21415-1: Determination of wet gluten (manual method)
• ISO 21415-2: Determination of wet gluten (mechanical means)
• ISO 21415-3: Dry gluten by oven drying method
• ISO 712: Moisture content of cereals and cereal products
• ISO 5725 series: Precision of measurement methods

Keywords: ISO 21415-4:2006, dry gluten, wet gluten, rapid drying method, wheat flour, gluten content, electrically heated drying plates, moisture content.