Animal and vegetable fats and oils - Determination of isolated trans isomers by infrared spectrometry (ISO 13884:2003)
ISO 13884:2003 specifies a method for the accurate determination of isolated trans bonds in natural or processed long-chain fatty acids, fatty acid esters and triglycerides with trans isomer levels greater than or equal to 5 %.The method is not applicable, or is applicable only with specific precautions, to fats and oils containing high levels (over 5 %) of conjugated unsaturation (e.g. tung oil) materials containing functional groups which modify the intensity of the C-H deformation about the trans double bond [e.g. castor oil containing ricinoleic acid or its geometrical isomer, ricinelaidic acid (12-hydroxy-9-octadecenoic acid)] mixed triglycerides having long- and short-chain moieties (such as diacetostearin) or in general, any materials containing constituents which have functional groups which give rise to specific absorption bands at or sufficiently close to interfere with the 966 cm-1 band of the C-H deformation of the isolated trans double bond.
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