Monitoring of lipid degradation products by solid-phase microextraction

The final sensory characteristic of vegetable oils is influenced by a serie s 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 step s of refining process on overall oxidative state and volatile compounds' fo rmation was investigated by means of solid-phase microextraction (SPME). Re sults were achieved by a 100-mum polydimethylsiloxane fiber in the sample's headspace. Hexanal, tr-2-hexenal, tr-2-heptenal, tr-2-octenal, tr-2-nonena l, tr,tr-2,4-decadienal, alpha -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 ionizati on detector was in 1-5 mg/kg depending on individual components. SPME was s uccessfully applied for both controlling decomposition of hydroperoxides du ring bleaching and aldehydes removal during deodorization. SPME and traditi onal static headspace techniques were compared. Static headspace gave bette r recovery and lower detection limit for compounds having higher volatility , but SPME made it possible to measure higher molecular weight aldehydes pr oviding a simple, reliable solution. (C) 2001 John Wiley & Sons, Inc.