Effect of cooking methods on bioactive compounds in vegetables

Abstract

Vegetables are very rich in health-promoting phytochemicals like flavonoids and phenolic compounds. The objective of the study was to investigate the effect of commonly used cooking (i.e., open and pressure cooking) methods on phytochemical content (i.e., polyphenols, flavonoids) and antioxidant activity levels as measured by DPPH and FRAP assay. Results showed that cooking methods has a great effect on phytonutrients and caused significant losses of flavonoids and increase in phenolics and antioxidant activity levels when compared with raw vegetables. Bitter gourd scored highest mean value, 1033.8 mg GAE/100g, and drumstick scored the lowest mean value, 222.3 mg GAE/100g, for total phenolic content. The flavonoid content ranged between 14.18 to 91.70 mg RE/100g and both the cooking methods decreased the flavonoid content in all the selected vegetables. Antioxidant activity levels were increased significantly (p< 0.01% and P