Effects of Traditional and Sous-vide Cooking on the Physicochemical Properties, Bioactive Compounds, and Mineral Composition of Certain Vegetables

Abstract

This study focused on evaluating the effects of traditional cooking methods (boiling and steaming) and sous-vide/vacuum cooking techniques on selected physicochemical properties, total phenolic and total flavonoid content, antioxidant capacity (DPPH, ABTS, FRAP, and CUPRAC), and mineral composition of five different vegetables (spinach, asparagus, cabbage, swiss chard, and purslane). According to the analyzed characteristics, vegetable type (VT) and cooking treatments (CT) were found to have a statistically significant effect (p < 0.01). When comparing the color values of raw and cooked vegetables, color stability varied depending on both the vegetable matrix and the evaluated parameter, with SV and steaming showing distinct matrix-dependent effects. VT and CT had statistically significant effects (p < 0.01) on dry matter and ash content, with thermal treatment being the primary driver of these changes. On a wet-weight basis, SV cooking generally yielded higher concentrations of total phenolic content (TPC) and total flavonoid content (TFC) compared to boiling, while exhibiting antioxidant activities (DPPH, FRAP, and CUPRAC) comparable to steam cooking. Principal component analysis (PCA) showed that the samples were generally separated according to VT, while the CT created a secondary differentiation, particularly in boiled samples. The PCA and correlation analysis results revealed that the relationships among mineral content, TPC, TFC, and antioxidant capacity were effective in the multivariate discrimination of the samples. Overall, the findings demonstrate that no single cooking method is universally superior across all parameters; rather, the determined concentrations and extractability of bioactive compounds and minerals strongly depend on the specific VT and CT.

Graphical Abstract