In this study, it is aimed to determine how different cooking processes (boiled (B), steamed (S), pressure boiled (PB), and pressure steamed (PS)) cause changes in various vegetables (potato, carrot, beet root, black carrot, celery, turnip, and sweet potato). The different process had a very significant effect (p < 0.01) on the L*, a*, b*, C*, H°, dry matter content, total soluble solids (TSS), ash content, pH, and titratable acidity values of vegetables. The process and vegetable kind were found to have a very significant effect (p < 0.01) on vitamin C and total phenolic content (TPC) of vegetables. It was revealed that the vitamin C was preserved better in S and PS than B vegetables. Except all PB, B, S sweet potato and cooked celery the TPC of other samples decreased at different rates (6.12%–88.30%) with cooking. It was found that the antioxidant activity (AA) of vegetables decreased with the process. It was determined that the mineral compositions of vegetables cooked with different methods were significantly different (p < 0.01) from raw vegetables, except for Fe. A positive correlation was detected between the samples' AA and color values. As a result, it was revealed that S vegetables preserved their color values better and the AA values of S vegetables were closest to raw vegetables.
Novelty Impact Statement
In terms of healthy nutrition, the differences in the characteristics of the food cooked with the heat treatment process in cooked foods has recently aroused an increasing interest. The study showed that physical and chemical properties, total phenolic content, and antioxidant properties were interrelated with different vegetables and different cooking methods. This was due to the different compositions and cooking techniques of vegetables, which determine the cell wall integrity and solubility of cell components during heat treatments. It was determined that the properties of steamed beetroot and black carrot were better preserved among different vegetables cooked with four different cooking methods (boiled, steamed, pressure boiled, and pressure steamed). The antioxidant activity of vegetables decreased with the treatment. Except for Fe, the mineral compositions of vegetables cooked by different methods were significantly different from raw vegetables. As a result, it was revealed that steamed vegetables preserved their color values better and the antioxidant activity values of steamed vegetables were closest to raw vegetables.