Cooking methods determine chemical composition and functional properties of squash blossoms: A study of microstructural and bioaccessibility changes

Abstract

[EN] This research aimed to evaluate the effect of different cooking methods (boiling, stir-frying, and steaming) on the microstructure, moisture, fat, protein, and glucose-derived carbohydrate contents, and the bioactive compounds (total carotenoids: CAR, total chlorophyll: CHLO, and total phenolic compounds: TPC) and antioxidant capacity (AC) of squash blossoms. Furthermore, we characterized polyphenolic compounds using HPLC and evaluated their bioaccessibility via in vitro digestions. Our results show that steaming and boiling do not affect moisture content. Only stir-frying decreased (p < 0.05) this parameter by 8 %. Additionally, the cooking methods increased (p < 0.05) protein and glucose-derived carbohydrate contents. All cooking methods changed the microstructure of the blossoms, probably due to the thermal and mechanical variations that result in moisture loss and degradation of cell wall components. As for the functional properties, boiling caused a greater loss of TPC (up to 96 %) and AC (up to 91 %). Stir-frying caused the greatest loss of CAR (up to 81 %) and CHLO (up to 84 %). The in vitro digestion assays showed changes in the bioaccessibility of CAR, CHLO, TPC, and AC in the cooked flowers compared to the fresh ones. Finally, kaempferol and gallic acid were the most resistant polyphenols to the cooking methods and in vitro digestion.