Effect of cooking on total antioxidant activity, polyphenols and flavanoid content in commonly consumed vegetables

Abstract

In India, most of the vegetables are processed before consumption and are cooked by boiling in water or roasting or deep-frying or microwaving. These cooking processes would bring about a number of changes in physical characteristics and chemical composition of vegetables. Thus, the present study helps to know the effect of different commonly used household processing methods on total antioxidant activity, flavanoid content and total polyphenols content of the selected vegetables. A total of six green leafy vegetables and five other vegetables namely red amaranthus, fenugreek, curry leaves, drumstick leaves, shepu, cabbage, ridge gourd, tomato, small brinjal, cluster bean and French bean were selected for the study. Vegetables were sorted, cleaned and edible portion of vegetables were cut into uniform size of one-centimeter cube using vegetable chopper except green leafy vegetables. The green leafy vegetables were also chopped into uniform pieces with knife as used at household level. The total polyphenolic content, flavanoid content and total antioxidant activity were analyzed in raw and vegetable cooked by two different household processing methods namely open boiling and pressure-cooking. It is a concluded that unprocessed or raw foods is healthier, especially vegetables but still cooking vegetables before consumption is a most widely practiced in India. It is important to know the best method of cooking to retain the health beneficial constituents in the vegetables. The present study indicates that pressure cooking in phenolics and flavanoids better to enhance the total antioxidant activity in Green leafy vegetables and other vegetables.