Effect of different drying methods on the product quality and bioactive polysaccharides of bitter gourd (Momordica charantia L.) slices

Abstract In this study, three drying methods, namely, hot-air drying, freeze drying (FD), and infrared radiation drying (ID), were applied to dry bitter gourd ( Momordica charantia L.) slices. Results showed that the drying methods had significant influences on appearance, color, rehydration ratio, and microstructure of dried bitter gourd. FD provided high-quality dried bitter gourd products due to the uniform honeycomb network and less collapsed structure. Three water-soluble bitter gourd polysaccharides (BPS-H, BPS-F, and BPS-I) were obtained from the bitter gourd dried using the three drying methods. The three polysaccharides exhibited similar preliminary structural characteristics with different monosaccharide compositions and molecular weights. BPS-I obtained from ID-dried bitter gourd had higher sugar and uronic acid contents than BPS-H and BPS-F. BPS-I exhibited stronger antioxidant activities and bile acid-binding capacity in vitro than BPS-H and BPS-F. Moreover, BPS-F and BPS-I showed significant α-amylase inhibitory activities in vitro.