Effect of vacuum infrared drying and tray drying on physicochemical properties, antioxidant activities, and α-amylase and α-glucosidase inhibition of banana bract powder

Banana bracts, a by-product of banana production, were subjected to vacuum infrared and tray drying at 50, 60, and 70°C, and the physicochemical properties, antioxidant activity, and digestive enzyme inhibition of banana bract powder were investigated. Banana bract powder contained 15.27 - 15.75% crude fibre. The yellowness, browning index, and water absorption of banana bract powder dried by a vacuum infrared dryer was higher than tray-dried powder. Bulk density and tapped density of banana bract powder dried by a vacuum infrared dryer were significantly lower, while the Carr index was higher than the tray-dried sample. Total phenolic content (TPC) and DPPH of powder dried by tray and vacuum infrared dryers decreased with increasing drying temperature. Vacuum infrared powder dried at 70°C effectively enhanced the uptake of glucose, and inhibited α-glucosidase activity compared to tray-dried powder, while tray drying at 60°C gave the highest α-amylase inhibition. The results indicated that banana bract powder could be added as a functional ingredient in food products.