EFFECT OF STEAM BLANCHING AND CONVECTION DRYING CONDITIONS ON COLOR, VITAMIN C, TOTAL PHENOLIC CONTENT, FLAVONOID CONTENT AND ANTIOXIDATION ACTIVITY IN SOURSOP (ANNONA MURICATA L.) LEAF TEA

Abstract

Blanching and drying techniques in food processing greatly affect the bioactive values. Research into this effect on soursop leaves raw material in the processing of tea which is a plant with anti-inflammatory, anti-cancer properties. Through a steam blanching process, 4 minutes were selected for compliance with TPC (208.43 ± 0.80 mgTE/g DM) and TFC (43.21 ± 0.71 mgQuercitin/mg DM). Along with the typical antioxidant activities such as TPC, TFC, the TAA, DPPH, ABTS content decreased sharply when heated by convection drying oven at 50-65°C. About 80% of the content is lost at the highest drying temperature. In addition, the Lab* color space of the fresh sample is dark brown transformed by heat, producing a characteristic yellowish hue when extracting custard leaf tea in hot water.