Functional and structural properties of dietary fiber from citrus peel affected by the alkali combined with high-speed homogenization treatment

In this research, the citrus fiber was modified by the alkali combined with high-speed homogenization (chemo-mechanical treatment) to improve its functional properties. The singly alkaline treated fiber was also evaluated to help us better understand the chemo-mechanical treatment's effect on citrus fiber. We compared the properties of modified citrus fibers with the untreated one and a commercial one (AQ Plus) which had excellent water holding capacity. The chemo-mechanical treated fiber's water swelling capacity was significantly improved to 35.56 mL/g (from 4.86 mL/g), higher than that of AQ Plus (28.25 mL/g). Its water holding capacity was increased to 25.52 g/g from 8.24 g/g, similar to that of AQ Plus (25.28 g/g). The chemo-mechanical treatment destroyed the citrus fiber's crystalline region, helped it form a rougher surface and porous inner structure, increased its soluble dietary fiber content and exposed more hydrogen bonds to water. Citrus fiber obtained from this chemo-mechanical method could be potentially used as food ingredients. [Display omitted] •The fiber water swelling and holding capacities highly improve after modifications.•The chemo-mechanical treatment significantly reduces fiber's crystalline value.•The chemo-mechanical treated citrus fiber has rough surface and porous microstructure.•The chemo-mechanical treatment help expose more hydrophilic groups in citrus fiber.•Pectin in citrus fiber may limit the re-aggregation of broken (hemi)cellulose chains.