Overview
ISO 29841:2009 - "Vegetable fats and oils - Determination of the degradation products of chlorophylls a and a′ (pheophytins a, a′ and pyropheophytins)" specifies a laboratory method to quantify chlorophyll degradation products in vegetable fats and oils. The procedure isolates pheophytin a, pheophytin a′ and pyropheophytin a from triglyceride matrices and determines their relative proportions by HPLC. The method is applicable to vegetable fats and oils only.
Key topics and technical requirements
- Scope and principle: Miniaturized silica-column chromatography separates pigments from the bulk lipid, followed by reversed-phase (RP18) HPLC analysis. Detection is typically photometric at 410 nm; higher-sensitivity analysis for some seed oils (e.g., rapeseed) uses fluorescence (excitation 430 nm, emission 670 nm).
- Sample preparation: Typical test portion ~300 mg dissolved in n‑heptane (or n‑hexane) and passed through a silica cartridge; eluates are collected, evaporated (≤ 20 °C), reconstituted in acetone and injected into HPLC.
- Chromatography conditions: RP18 column (250 mm × 4.0–4.6 mm, 5 µm). Mobile phase is a water–methanol–acetone mixture (approx. 4/36/60 vol%); flow rate ~1.0 mL/min. Annex C describes a direct HPLC with fluorescence detection alternative.
- Quantification: Relative peak‑area calculation assumes equal response factors; pyropheophytin a content is reported as a percentage of the sum of pheophytin a, a′ and pyropheophytin a, reported to one decimal place.
- Precision and validation: Annex B summarizes an interlaboratory study (16 laboratories) and gives repeatability and reproducibility guidance. Testing, reporting, and sampling follow ISO practices (sample prep per ISO 661; sampling guidance in ISO 5555).
- Handling and safety: Pheophytins are light-sensitive and oxidize easily - store samples cold, protected from light, avoid plastics. Use analytical-grade solvents and follow hazardous‑substance regulations.
Practical applications
- Quality control and authenticity testing of olive oil, rapeseed oil, and other vegetable oils by detecting chlorophyll degradation markers associated with processing, storage or heat exposure.
- Shelf-life and processing research: monitoring chlorophyll degradation, refining effects, and thermal damage in edible fats and oils.
- Regulatory and certification labs needing standardized, comparable measurement of pheophytins and pyropheophytins for product grading or compliance.
Who should use ISO 29841:2009
- Food chemistry and oil analysis laboratories
- Producers and quality assurance teams in edible oil industry
- Research groups studying pigment degradation, oil stability, and processing effects
- Accreditation bodies and testing labs requiring standardised HPLC methods for chlorophyll degradation products
Related standards
- ISO 661 - Preparation of test sample for fats and oils
- ISO 5555 - Sampling of animal and vegetable fats and oils
- ISO 5725 (Parts 1 & 2) - Accuracy, repeatability and reproducibility evaluation
Keywords: ISO 29841:2009, chlorophyll degradation, pheophytin, pyropheophytin, vegetable oils, HPLC, RP18, fluorescence detection, silica cartridge, oil quality control.