The effects of common cooking methods (fresh, boiling, and steaming) on the total polyphenols, total flavonoids, and glucosinolates as well as the antioxidant activities in both water and 80% ethanol extracts of Brussels sprouts were determined. In the water extract of fresh Brussels sprouts, the total polyphenols were 31.11 mg/g, which were not significantly different from those of the steamed extract (31.02 mg/g). On the other hand, the boiling of Brussels sprouts showed 17.89 mg total polyphenols, which was 42.49% lower than those of the fresh sample. In the 80% ethanol extracts, the total flavonoid content decreased to 3.96% and 6.39%, respectively, compared to the fresh samples. Nine glucosinolates, including progoitrin, glucoraphanin, sinigrin, gluconapin, glucoiberverin, glucoerucin, glucobrasscin, gluconasturtin, and 4-methoxyglucobrasscin were identified by HPLC in Brussels sprouts. Regardless of the cooking method, the total polyphenol and total flavonoid contents were higher in the 80% ethanol extract than in the water extract. The antioxidative activities of the 80% ethanol extracts were higher than those of the water extracts. Therefore, to minimize the loss of bioactive substances in Brussels sprouts, it is desirable to use steaming or consuming them fresh instead of using boiling water.

Keywords: Brussels sprouts, antioxidant, glucosinolate, cooking