Determination of dialkyl ketones (DAK) in interesterified lipids by GC-FID and GC-MS

Dialkyl ketones (DAK) is a class of by-product that can be produced during the interesterification of lipids. Interesterification is a well-known technique in food field that remodels lipid structures to obtain new rheological and functional properties. Interesterfication may be carried out through an enzymatic or a chemical way. The latter was shown to lead to the production of by-products identified as DAK.
The aim of this work was to optimize and validate an analytical method to detect DAK in interesterified lipids. A first saponification step was optimized using microwave assisted saponification with simultaneous extraction of the unsaponifable fraction, followed by a solid-phase extraction (SPE) purification step. Quantification was carried out in gas chromatography (GC) coupled to flame-ionization detector (FID) after the confirmation of the identity in GC – mass spectrometry (MS). The method was fully validated and applied to real samples.