Comparison of antioxidative properties of raw vegetables and thermally processed ones using the conventional and sous-vide methods

The study determines the antioxidant properties of methanol vegetable extracts from raw vegetables, conventionally cooked vegetables and sous-vide. In the research, two methods were used: free radical scavenging DPPH (mu M Trolox) and the reduction of Fe3+ to Fe2+ - FRAP (mu M Fe2+). Antioxidative properties for raw vegetables were obtained with the range of 7.47-235 (mu M Trolox/100 g of vegetables) and 2.66-103 (mu M Fe2+/100 g of vegetables), for vegetables after the conventional cooking process 6.15-657 (mu M Trolox/100 g of vegetables) and 3.03-99.9 (mu M Fe2+/100 g of vegetables), for vegetables after the sous-vide process 4.45-648 (mu M Trolox/100 g of vegetables) and 3.06-99.9 (mu M Fe2+/100 g of vegetables). For some vegetables, an increase in the antioxidative potential was observed as a result of cooking processes; however, it was much higher for the sous-vide technique. All results were subjected to a one-way analysis of variance (ANOVA) and, if significant differences were revealed, the POST-HOC Duncan test was used (alpha = 0.05).