Degradation process of autoxidized methyl linoleate.

Abstract

Methyl linoleate (ML) and methyl linoleate hydroperoxides (MLHPO) were degradated by incubating under an aerobic condition at 37°C for a week. Identification of secondary degradation products (SP) by gas chromatography-mass spectrometry showed that the high proportions of hexanal, methyl octanoate and 8-formyl methyl octanoate (8-FMO) were found in degradated ML or MLHPO. In degradation of MLHPO, the decrease of peroxide value (POV) was slower than that of conjugated diene. In the earlier stage, POV was scarcely decreased, but in the later stage, MLHPO disappeared and another secondary hydroperoxides were produced. ML decreased linearly during 4-day incubation and the amount reached to 10% of the original one. The formation of 8-FMO was delayed to the increase of POV. Degradation process of autoxidized ML was discussed with the changes of POV, UV absorption and the amount of 8-FMO, and a formation mechanism of some SP was proposed.