Physicochemical characterization of five types of citrus dietary fibers

The chemical composition, physicochemical and in vitro biochemical properties of dietary fibers (DFs) from five types of citrus fruit peels (orange, grapefruit, lemon, gonggan and ponkan) were investigated. The contents of total, soluble and insoluble dietary fibers in citrus fruit peels had no significant difference (p>0.05) and the binding capacities of soluble dietary fibers (SDFs) of orange, lemon, gonggan and ponkan for sodium cholate and cholesterol were significantly (p<0.05) lower than those of grapefruit SDF. The more sponge-like porous network structure of grapefruit SDF could lead to its higher binding capacities. All the SDFs of citrus fruit peels exhibited a near-Newtonian fluid behavior, and grapefruit SDF solution had higher viscosity than that of others. The main monosaccharide of orange SDF was glucose (33.87%), while arabinose was the main monosaccharide in the SDFs from grapefruit, lemon, gonggan and ponkan (38.67–44.83%). To the water-holding, oil-holding and swelling capacities of insoluble dietary fiber (IDF), the IDF from grapefruit and orange were the highest and lowest one respectively.