Thermal processing-induced changes in volatilome and metabolome of Brussels sprouts: focus on glucosinolate metabolism

This study aimed to investigate the influence of different thermal treatment methods (boiling, steaming) on the metabolome and volatilome of Brussels sprouts. Targeted, quantitative analysis of primary metabolites (amino acids and sugars), glucosinolates as well as untargeted analysis of volatile organic compounds (VOCs) were performed. The composition of primary metabolites was affected only by boiling, where the loss of nutrients was observed. Glucosinolate content increased after cooking, which can be explained by the loosening of the plant tissues and its better extractability. Most marked changes were noticed in the volatilome. Among the degradation products of glucosinolates, isothiocyanates were the main chemical group in the raw and boiled vegetable. In contrast, steaming favored the formation of nitriles. Another dominant group of VOCs were aldehydes, which were the most abundant in raw Brussels sprouts and their level significantly decreased after thermal treatment. It is well known that isothiocyanates are substances with widely proven bioactive properties. Therefore, their formation in the glucosinolate degradation process is favorable. Based on the obtained results, it was concluded that boiling seems to be the most beneficial form of Brussels sprouts’ processing.