Physical character, total polyphenols, anthocyanin profile and antioxidant activity of red cabbage as affected by five processing methods

Understanding the influence of processing methods on the phytochemicals of fruits and vegetables is of importance in retaining the health-benefiting properties of those products. The aim of this study was to investigate the effects of five processing methods including freeze drying (FD), hot air drying (HD), water boiling (WB), steaming (ST), and pickling (PI) on the physical character, total polyphenols, anthocyanin profile and antioxidant activity of red cabbage. Different color and texture were observed after different processing methods. Total anthocyanin content was reduced by 73%, 72%, 41%, 16%, and 30% in FD, HD, WB, ST and PI processed red cabbage, respectively. PI samples showed the highest values of total polyphenols and DPPH scavenge activity among all the processed red cabbage. Both FD and HD samples had relatively low values of total polyphenols and DPPH scavenge activity. However, FD sample had the highest FRAP values. UPLC-QqQ-MS/MS analysis showed that fresh red cabbage contained 22 anthocyanins among which cyanidin-3-diglucoside-5-glucoside was the prominent. Compared with drying process, WB, ST and PI decreased the loss of most of the anthocyanin component in red cabbage. Correlation analysis indicated that antioxidant capacity as determined by DPPH of red cabbage was positively and significantly correlated with the total anthocyanins. This study suggested that drying induced significant loss of phytochemicals in red cabbage, and WB, ST, as well as PI were advisable ways for daily consumption of red cabbage considering the bioactive components. Especially, ST was the best way to retain anthocyanins in red cabbage.