Physicochemical properties and in vitro antidiabetic potential of fibre concentrates from onion by-products

Onion by-products, Paste and Bagasse, were used to produce fibre concentrates (FCs), which were studied for dietary fibre (DF) content, physicochemical properties, effects on glucose adsorption, in vitro glucose diffusion, alpha-amylase activity and starch digestibility. FC dietary fibre was composed of cellulose and pectic polysaccharides with different degree of branching. FCs had lower bulk densities, and higher oil holding and cation exchange capacities, as well as higher hydration properties, than cellulose. Onion FCs had the desired physicochemical properties as fibre sources or low-calorie bulk ingredients in food applications. Both onion FCs were found to have higher glucose-adsorption capacity than cellulose. The retardation of glucose diffusion by FCs were higher than cellulose. All FCs reduced the glucose production rate by inhibiting alpha-amylase activity, and decreased starch digestibility. The results verified the hypoglycaemic effect and the in vitro antidiabetic potential of onion by-product FCs. (C) 2017 Elsevier Ltd. All rights reserved.