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

Abstract

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.