Effects of microwave pretreatment on oxidation of pressed rapeseed oil during accelerated storage

To investigate advantages of microwave pretreatment for oil storage, oxidative stability of pressed rapeseed oil with microwave pretreatment(M-RO) was evaluated, while pressed rapeseed oil(RO) and RO with 200 ppm tertiary butylhydroquinone added(T-RO)were used for comparison. Oil samples were collected after accelerated storage at 60 oC in dark for 0-32 d. A total of 37 oxidized volatile compounds were identified and 9 typical key compounds were quantified by solid-phase microextraction gas chromatography/mass spectrometry(HS-SPME-GC/MS). Correlation analysis showed that lipid oxidation parameters and induction time(IP) had significant association with typical indicators of volatile oxidized compounds. Hexanal and(E,E)-2,4-heptadienal were most suitable for differentiating RO sample at different storage times while 1-hexanol, 1-heptanal and(E)-2-octenal were suitable for T-RO sample. To M-RO sample, 5 substances described above together can provide a guide for monitoring lipid oxidation. M-RO has better oxidation resistance than RO, with advantage of 4 d in accelerated conditions both in sensory evaluation and PCA analysis. However, it still produces more volatile oxidized compounds and has higher peroxide value(PV) and p-anisidine value(p-AV) than T-RO sample at any sampling point.Anti-oxidation efficiency of rapeseed oil can be promoted via microwave pretreatment. This work provid new clues of benefits about microwave pretreatment in oil storage.