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 (µM Trolox) and the reduction of Fe3+to Fe2+ – FRAP (µM Fe2+). Antioxidative properties for raw vegetables were obtained with the range of 7.47–235 (µM Trolox/100 g of vegetables) and 2.66–103 (µM Fe2+/100 g of vegetables), for vegetables after the conventional cooking process 6.15–657 (µM Trolox/100 g of vegetables) and 3.03–99.9 (µM Fe2+/100 g of vegetables), for vegetables after the sous-vide process 4.45–648 (µM Trolox/100 g of vegetables) and 3.06–99.9 (µM 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 (α = 0.05).