Overview
EN ISO 11052:2006 (adoption of ISO 11052:1994) specifies a laboratory method to determine the yellow pigment content - the extractable carotenoids - in durum wheat flour and semolina (Triticum durum L.). The standard is intended for routine quality assessment and provides a reproducible spectrophotometric procedure used across mills, pasta manufacturers and testing laboratories.
Key elements of the method include a solvent extraction with water-saturated n-butanol, filtration of the clear extract and photometric evaluation against β-carotene calibration standards.
Key Topics
- Scope: Measurement of extractable carotenoids (expressed as mg β-carotene per 100 g dry matter) in durum wheat flour and semolina.
- Principle: Extraction at room temperature using water-saturated n-butanol, followed by absorbance measurement at 440 nm and comparison to β-carotene standard solutions.
- Sample & reagents: Typical test sample is 10 g (ground to appropriate particle size). Reagents include water-saturated n-butanol, diethyl ether and crystalline synthetic β-carotene for calibration.
- Apparatus: Standard laboratory equipment is required - grinder, spectrometer capable of 440 nm, volumetric flasks, Erlenmeyer flasks and hard fluted filter paper.
- Procedure highlights: Disperse 10 g sample in ~50 ml solvent, shake and allow extraction overnight (16–18 h), filter and measure optical density of the clear filtrate at 440 nm. Use prepared β-carotene standards to build a calibration curve.
- Reporting: Results are expressed on a dry-matter basis; test report should include method details, moisture content (by ISO 712), and any deviations or incidents.
Applications
- Quality control in flour mills and pasta production: monitor carotenoid (yellow pigment) levels to ensure consistent product appearance and quality.
- Raw material specification: evaluate durum wheat lots and semolina batches for desirable pigment content during purchasing and storage decisions.
- Laboratory standardization: provides a validated procedure for inter-laboratory comparison and routine QC testing.
Practical benefits include a standardized, repeatable measurement that supports product consistency, supplier evaluation and regulatory or labeling needs related to pigment content.
Related Standards
- ISO 11052:1994 / EN ISO 11052:2006 - this procedure (CEN adoption)
- ISO 712 - determination of moisture content (routine reference method) - required for reporting dry-matter results
- ISO 2170 - sampling of milled products (recommended sampling practices)
- ISO 5725 - precision of test methods (repeatability and reproducibility evaluation)
For laboratories implementing this method, follow the full EN ISO 11052:2006 text for detailed instructions, calibration procedures and precision data from interlaboratory studies.