Monitoring of lipid degradation products by solid-phase microextraction*

The final sensory characteristic of vegetable oils is influenced by a series of aroma compounds and volatile oxidation products formed during storage and processing. Crude sunflower oil was stored at room temperature and was regularly refined by applying physical refining process in laboratory scale studying lipid degradation. Effect of long-term storage and different steps of refining process on overall oxidative state and volatile compounds' formation was investigated by means of solid-phase microextraction (SPME). Results were achieved by a 100-μm polydimethylsiloxane fiber in the sample's headspace. Hexanal, tr-2-hexenal, tr-2-heptenal, tr-2-octenal, tr-2-nonenal, tr,tr-2,4-decadienal, α-pinene, pentylfuran, 1-octen-3-ol were used for external standard calibration. It was proved that hexanal and tr,tr-2,4-decadienal are aldehydes, which appear first in sunflower oil during long-term storage. Detection limit using splitless injection and flame ionization detector was in 1–5 mg/kg depending on individual components. SPME was successfully applied for both controlling decomposition of hydroperoxides during bleaching and aldehydes removal during deodorization. SPME and traditional static headspace techniques were compared. Static headspace gave better recovery and lower detection limit for compounds having higher volatility, but SPME made it possible to measure higher molecular weight aldehydes providing a simple, reliable solution. © 2001 John Wiley & Sons, Inc. J Micro Sep 13: 215–220, 2001