Abstract
Bitter gourd has numerous health-promoting effects on the human body. However, its use has been greatly limited due to its poor acceptance by consumers, resulting from its strong bitterness. This study investigated the effects of five wall materials, namely, soybean protein isolate, gum arabic, maltodextrin, resistant starch, and a soybean lecithin calcium caseinate mixture, on the physicochemical properties of spray-dried bitter gourd powders. The results showed that all five wall materials reduced the moisture content, water activity, browning degree, agglomeration, and bitterness of the spray-dried bitter gourd powder. Maltodextrin was found to be the most effective at reducing water activity, while soybean protein isolate was best at protecting the colour, and the soybean lecithin calcium caseinate mixture was best at reducing hygroscopicity and masking bitterness. Additionally, all five wall materials improved the preservation of flavonoids, saponins, and vitamin C, with soybean protein isolate being the most effective in improving the total flavonoid retention ratio and the soybean lecithin calcium caseinate mixture being the best in improving the retention ratios of total saponins and vitamin C. The spray-dried bitter gourd powder prepared with soybean protein isolate had the highest antioxidant activity and α-glucosidase inhibitory activity. These results are significant for understanding the relationship between wall materials and the physicochemical properties of spray-dried powder. Additionally, these materials provide bitter gourd product manufacturers with useful guidance for producing high-quality products. Furthermore, the results could provide useful insights for processing fruits with similar product characteristics, thus contributing to the enrichment of food processing knowledge.