Production and Optimization of Functional Fiber Supplement Based on Food By-products Using Extrusion Technology

In this study, the use of extrusion technology in the production of functional fiber supplement from by-products of tomato and rice processing industries (tomato pomace and rice bran) was investigated. A rotatable central composite design was used to investigate the processing and formulation variables including screw speed (120-160 rpm), moisture content (12-18%) and tomato pomace to rice bran ratio (25-75%). The functional and physicochemical properties of texturized products including water absorption index (WAI), swelling (SW), hardness, and soluble dietary fiber content were evaluated. The results showed that WAI of product increased with the increasing of screw speed and tomato pomace to rice bran ratio. Increasing tomato pomace to rice bran ratio and moisture content caused an increase in swelling. The hardness of fiber supplement also increased with increasing tomato pomace to rice bran ratio. Increasing screw speed increased the content of soluble dietary fiber. According to the results, the optimized processing conditions for the production of fiber supplement with desirable properties including WAI (4.64 g/g), SW (4.61 ml/g), hardness (89.08 N) and soluble dietary fiber (11.09%) were as following, moisture content of 14.06%, tomato pomace to rice bran ratio of 26.43% and screw speed of 120 rpm.