Flavor precursors identification and thermal degradation mechanisms of glucoerucin in fragrant rapeseed oil

The degradation products of glucosinolates endow rapeseed oil with a characteristic aroma, however, the mechanism remains unclear. In this study, 29 individual glucosinolates were identified in six rapeseeds (Brassica napus) using widely targeted metabolism, including 22 aliphatic, 5 aromatic, and 2 indole glucosinolates. Characterization of thermally induced aromas from new precursors-glucoerucin was performed in different pH matrices via headspace-solid phase microextraction and gas chromatography-mass spectrometry. Six glucoerucin degradation were identified including 5-methylthio-pentanenitrile and dimethyl trisulfide et al. The results of thermal model showed that Glucoerucin could generate volatile 5-methylthio-pentanenitrile via dehydration and formed 1-isothiocyanato-4-(methylsulfanyl)butane via (394.9 μg/kg) by the Rosen rearrangement further product pungent odors 4-isothiocyanato-1-butene (5.6 μg/kg) at pH 5. Sulfur-containing compounds included dimethyl disulfide and dimethyl trisulfide can provide pungent and cabbage notes in matrices at pH 7 and 9. The results provide a new understanding in the forming mechanism of characteristic odor in fragrant rapeseed oil.