ISO 6800:1997
Animal and vegetable fats and oils — Determination of the composition of fatty acids in the 2-position of the triglyceride molecules
Animal and vegetable fats and oils — Determination of the composition of fatty acids in the 2-position of the triglyceride molecules
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 12
- Дата публикации:
- 18 декабря 1997 г.
- Издание:
- ISO IS 6800 edition 2 version 1
- ICS:
- 67.200.10
La présente Norme internationale spécifie une méthode de détermination dans les corps gras d'origines animale et végétale de la composition de la fraction des acides gras estérifiés en position 2 (position β ou position interne) dans les triglycérides. En raison des particularités d'action de la lipase pancréatique, la méthode s'applique seulement aux corps gras ayant un point de fusion inférieur à 45 °C. Elle n'est pas applicable sans restrictions à tous les corps gras, en particulier à ceux renfermant des quantités importantes -- soit d'acides gras ayant 12 atomes de carbone ou moins (par exemple huiles de coprah et de palmiste, matières grasses butyriques du beurre); -- soit d'acides gras ayant 20 atomes de carbone et plus et d'insaturation élevée (plus de quatre doubles liaisons) (par exemple huiles de poissons et d'animaux marins); -- soit d'acides gras possédant des fonctions oxygénées secondaires. NOTE -- Les acides gras avec doubles liens en position (n-16) à (n-11) (par exemple acide pétrosélinique) ne sont convertis que très lentement par lipase pancréatique, ce qui pourrait donner des résultats erronés.
Abstract
Overview
ISO 6800:1997 specifies a laboratory method for the determination of fatty acids esterified in the 2‑position (β or internal position) of triglyceride molecules in animal and vegetable fats and oils. The procedure combines partial enzymatic hydrolysis with pancreatic lipase, isolation of 2‑monoglycerides by thin‑layer chromatography (TLC), and fatty‑acid profiling by gas chromatography (GC) after methylation.
The standard is applicable only to fats/oils with a melting point below 45 °C and lists important limitations for certain matrices (short‑chain fatty acids, highly unsaturated long‑chain fatty acids, fatty acids with secondary oxygenated groups, and slow‑reacting double‑bond positions).
Key topics and technical requirements
- Scope and limitations: Method suited for many edible fats and oils but not unreservedly for copra, palm kernel, some fish/marine oils, or fats with oxygenated secondary groups.
- Sample preparation: Follow ISO 661 for test‑sample prep; determine acidity per ISO 660. Neutralize if free acidity > 3% (m/m) before purification.
- Purification: Column chromatography on activated neutral alumina; solvents include hexane/light petroleum and 2‑propanol/ethanol.
- Enzymatic hydrolysis: Use pancreatic lipase (activity 8–20 units/mg), buffer at pH ~8, sodium cholate and CaCl2; hydrolysis carried out at controlled temperatures (40 °C) to yield 2‑monoglycerides.
- Isolation by TLC: Silica plates (boric‑acid impregnated to prevent acyl migration), developing solvent (hexane/diethyl ether/formic acid), and detection with 2',7'‑dichlorofluorescein/UV.
- Analysis by GC: Convert monoglyceride fatty acids to methyl esters per ISO 5509 and analyze according to ISO 5508.
- Quality/precision: Repeatability and reproducibility limits are specified (e.g., repeatability ≤ 0.2% m/m for constituents < 5% m/m; reproducibility ≤ 0.5% m/m for constituents < 5% m/m). Results expressed as % (m/m) of total fatty acids of the 2‑monoglycerides, reported to one decimal place.
Applications and users
ISO 6800:1997 is useful for:
- Food and edible oil quality control laboratories
- Lipid chemists and research institutions studying triglyceride structure and positional distribution
- Regulatory and conformity testing where 2‑position fatty acid composition impacts nutritional, functional or labeling claims
- Manufacturers assessing oil processing effects or authenticity/adulteration of fats
Keywords: ISO 6800:1997, determination of fatty acids in 2‑position, triglyceride 2‑position, pancreatic lipase method, 2‑monoglycerides, TLC, gas chromatography, fatty acid composition.
Related standards
Технические детали
- Технический комитет
- ISO/TC 34/SC 11 - Animal and vegetable fats and oils
- SKU
- ISO 6800:1997
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