ISO 17715:2025

Overview

ISO 17715:2025 specifies an amperometric method for determining the content of damaged starch in flour from wheat (Triticum aestivum L.). The standard applies to flour produced by industrial or laboratory milling and defines the analytical principle, reagents, equipment, test procedure and the expression and precision of results. This second edition (2025) updates the method from ISO 17715:2013 and allows the use of a ready-to-use sodium thiosulfate solution.

Key topics and technical requirements

• Analytical principle: Measurement of iodine absorption kinetics in an aqueous medium using an amperometric electrode. Damaged starch is inferred from iodine absorption and reported as iodine absorption percentage (A, %) and as Chopin–Dubois units (UCD).
• Scope and applicability: Valid for wheat flours from industrial or laboratory milling; results for semi‑wholemeal or wholemeal flours require careful interpretation in the absence of validity studies.
• Reagents: Examples include boric or citric acid, potassium iodide and sodium thiosulfate (ready-to-use 0.1 mol/L or prepared solution). Use analytical-grade water.
• Equipment: Typical laboratory apparatus and a dedicated device (document developed using the CHOPIN SDmatic® reaction vessel and sample holder). Other equivalent devices may be used if they produce equivalent results.
• Procedure highlights:
  • Reagent dosing (e.g., 3.0 g boric acid or 1.5 g citric acid, 3.0 g KI, ~120 mL water and a drop of thiosulfate).
  • Sample test portion: 1 000 g ± 0.100 g placed in the device’s sample holder.
  • Test runtime: approximately 6–7 minutes; two determinations per sample are required.
  • Cleaning and electrode care after each test.
• Expression of results and units: Report A (%) to two decimal places and UCD to one decimal place; manufacturer equations may convert to other units.
• Precision and quality criteria: Repeatability and reproducibility limits are specified (formulas and tables in Clause 10 and Annex A). Two determinations’ mean is accepted if within repeatability limits; otherwise repeat testing.

Practical applications

• Flour quality control: Quantifying starch damage to predict water absorption and behavior in baking and other food processes.
• Mill laboratories and QA teams: Routine monitoring of milling performance and flour specifications.
• Food ingredient suppliers and processors: Adjusting dough formulations, enzyme dosing and processing parameters based on starch damage.
• Research and method validation: Comparative studies of milling conditions, wheat varieties and process optimization.

Who should use ISO 17715:2025

• Quality assurance managers in flour mills and cereal processing plants
• Laboratory analysts in food testing and cereal research labs
• Equipment manufacturers developing amperometric devices for starch damage measurement
• Regulatory and standards professionals specifying analytical methods for flour characterization

Related standards

• ISO 27971 - laboratory milling methods (referenced for lab milling)
• ISO 24333 - recommended sampling for cereals and flours
• ISO 712-1 - moisture determination (for reporting on constant water basis)
• ISO 20483 / ISO 16634-2 - protein determination (for corrections on constant protein basis)

Keywords: ISO 17715, damaged starch, starch damage measurement, amperometric method, flour from wheat, CHOPIN SDmatic, iodine absorption, Chopin–Dubois units, flour quality, repeatability, reproducibility.