Widely targeted metabolomics reveal the glucosinolate profile and odor-active compounds in flowering Chinese cabbage powder

Widely targeted metabolomics were performed to explore the differences in glucosinolate and odor-active compound levels between flowering Chinese cabbage powder (FCCP) under vacuum-drying and oven-drying conditions. Twenty-three aliphatic, five indole, and three aromatic glucosinolates were identified in two pretreated FCCP. Higher aliphatic glucosinolate levels were retained in vacuum-dried cabbage powder compared to oven-dried samples, and they were negatively correlated with treated temperatures. A total of 36 major odor contributing compounds were detected, including 5 sulfur compounds, 10 aldehydes, 9 heterocyclic compounds, 7 nitriles, 3 acids, and 2 others. 5-Hexenenitrile and (methyldisulfanyl)methan, provide typical pungent, sulfous, and vegetable notes in FCCP. Four major GSLs, namely 2(R)-hydroxy-3-butenyl glucosinolate, (2S)-2-hydroxy-4-pentenyl glucosinolate, 5-(methylthio)pentyl glucosinolate and 2-phenylethyl glucosinolate were the key precursors to form odor-active compounds. Higher temperatures in thermal effects promotes the formation of sulfur-containing and nitrile compounds compared to the vacuum-dried ones. This work can provide a guide for flavor and nutrition retention in FCCP process.

Thermal oxidation of rice bran oil during oven test and microwave heating

The purpose of the present study was to evaluate the oxidative stability of physically refined rice bran oil (RBO) under oven heating at 63 °C and microwave heating conditions by absorptivity. Oil samples with tertiary-butylhydroquinone (TBHQ) (100 ppm and 200 ppm), citric acid (CA), butylhydroxyanisole/butylhydroxytoluene (BHA/BHT) and in other combination, BHA/BHT+CA were submitted to oven test for 6 days, and the linear coefficient of correlation between peroxide value and absorptivity at 232 nm was determined. The gradual increase in peroxide value and absorptivity at 232 nm was observed in all the RBO samples, control and antioxidant added. RBO samples added with tertiary-butylhydroquinone (TBHQ) had shown the least peroxide value and absorptivity as 6.10 and 5.8 respectively, when added at a concentration of 200 ppm whereas; the control RBO samples had shown the maximum values. The peroxide values obtained from the correlations during the oven test were found closely correlated with the peroxide values obtained during the microwave oven heating experimentally. The effect of microwave heating on the oryzanol content and p-anisidine value was also observed and the correlation to the oven test was established. The oryzanol content and p-anisidine values obtained after oven heating when correlated to the microwave heating data showed the oryzanol content 13,371, 13,267 and 13,188 ppm after 1 day, 4 days and 5 days respectively which were closely correlated with the experimental value.