The effect of cooking methods on total phenolic and antioxidant activity of selected 'ulam'

Abstract

This study was conducted to evaluate the total phenolic and antioxidant activity of extracts from four species of 'ulam', namely Psophocarpus tetraganolobus (winged bean/kacang botor); Momordica subangulata (bitter cucumber/peria katak); Musa L. inflorescent (jantung pisang) dan Solanum tarvum Swartz (devil's fig/terung pipit). There are five cooking methods were used in this study. There were fresh; blanching; boiling; microwave and steaming. Methanol was used as extracting solvent. The total phenolic were measured by Folin-Ciocaltue method while antioxidant activity were measured by 2,2,-diphenyl-2-picryl-hydrazyl (DPPH) method. The results of total phenolic were compared with gallic acid while antioxidant activities were compared with butylated hydroxytoulene or BHT (synthetic antioxidant). Total phenolic content of fresh 'ulam' ranged from 0.44 to 1.06 mg/100 g (as gallic acid equivalent). The total antioxidant activity of fresh 'ulam' ranged from 28.86 % to 36.01 %. In total phenolic content, microwaving method was seen to have the highest while boiling method was the lowest in total phenolic content. In DPPH method, steaming samples showed the highest antioxidant activity while blanching method was seen to have the lowest antioxidant activity. The highest total phenolic as gallic acid equivalent showed that devil's fig in microwave cooking method while the lowest was in Musa L. inflorescent in blanching method.