Topical Area: Dietary Bioactive Components
Objectives : Cauliflower is one of the cruciferous vegetables and contains various physiologically active substances such as glucosinolates, polyphenols, and flavonoids. Unlike ordinary vegetables, cruciferous vegetables are often consumed by cooking through heat treatment. The purpose of this study was to investigate the effects of different heating procedures, in particular steaming and boiling, on glucosinolate, total polyphenol, and total flavonoid concentrations in cauliflower. In addition, antioxidant activity was compared between fresh uncooked, steamed, and boiled cauliflower, which are the main methods of preparing cauliflower before consumption.
Methods : Glucosinolates in uncooked, steamed, and boiled cauliflower were subjected to high-pressure liquid chromatography. Total phenolic and total flavonoid content and antioxidant activities in cauliflower extracted in both water and 80% ethanol were determined.
Results : Eight glucosinolate peaks were detected in cauliflower representing glucoiberin, progoitrin, glucoraphanin, sinigrin, gluconapin, glucoiberverin, glucobrassicin, and gluconasturtiin. Boiling cauliflower significantly decreased the glucosinolate, total polyphenol, and total flavonoid concentrations compared to those of uncooked or steamed cauliflower. The results clearly indicated that health-promoting compounds in cauliflower are significantly affected by different cooking methods, showing that uncooked > steamed > boiled. The amounts of total polyphenols and total flavonoids contained within uncooked cauliflower extracted by 80% ethanol were higher than those in the steamed and boiled extracts. The highest antioxidant activity was observed in uncooked cauliflower extracted in 80% ethanol compared to that of water extracts at the same concentration. Steamed and boiled cauliflower extracts showed lower antioxidant activity.
Based on these results, fresh uncooked cauliflower is optimal in terms of the content of health-promoting compounds and antioxidant activity. It may be desirable to use steaming rather than boiling to minimize the loss of glucosinolates when storing, pretreating, processing, and cooking cruciferous vegetables.
Funding Sources :
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea.
Hankyong National University