Comparison of the chemical composition and physicochemical properties of different fibers prepared from the peel of Citrus sinensis L. Cv. Liucheng.

Fiber-rich fractions (FRFs) including soluble and insoluble dietary fibers (SDF and IDF), alcohol-insoluble solid (AIS), and water-insoluble solid (WIS) were isolated from the peel of Citrus sinensis L. cv. Liucheng for analysis and tests. The peel was rich in insoluble FRFs (IDF, AIS, and WIS; 476-515 g kg(-1) of peel), which were mainly composed of pectic substances and cellulose, and also contained pectic polysaccharide-rich SDF (94.1 g kg(-1) of peel). These insoluble FRFs had water-holding capacities (15.5-16.7 mL g(-1)), oil-holding capacities (2.35-5.09 g g(-1)), cation-exchange capacities (454-997 mequiv kg(-1)), and swelling properties (14.6-21.1 mL g(-1)) much higher than those of cellulose. These results recommended the consumption of these peel insoluble FRFs of desired physicochemical properties as sources of food fibers or low-calorie bulk ingredients in food applications requiring oil and moisture retention. Further investigations on the physiological functions of these peel FRFs using animal-feeding experiments are underway.