Effect of process conditions and formulation on physicochemical and functional properties of textured fiber supplement (tomato pomace-rice bran)

The food industry generate large amount of wastes annually around the world Food wastes are excellent source of nutritional compounds such as proteins, dietary fibers, antioxidants, and several types of micronutrients Therefore management of recycling food by-products is more valuable with maximum efficiency, in order to manufacture added value and low cost food products. Recently the processing of various types of by- products by extrusion cooking technology has been considered as a high- efficiency process. In this project, the rotatable central composite design was used to investigate the effects of formulation variables containing tomato pomace : rice bran ratio (25: 75-75: 25% w/w), feed moisture content (12-18%) and extrusion conditions including screw speed (120-160rpm) on functional and physicochemical properties of extruded fiber supplement from (tomato pomace- rice bran) including (oil absorption index, bulk density, color indexes (L،* a*,b*) , antioxidant activity and water activity (aW)). The results showed that properties of extrudates were affected by formulation and extrusion conditions. Enhancement of screw speed increased oil absorption index The addition of fiber supplement increased the color indexes(a*,b*) whereas lightness (L*) and bulk density decreased. Increasing screw speed and moisture content caused a decrease in the antioxidant activity. By increasing moisture content and tomato pomace increased water activity (aW) of extruded products. According to optimization results, to provide a modified fiber supplement for application in dietary foods optimum condition was found to be the tomato pomace : rice bran ratio of (25: 75% w/w), screw speed of (137/63 rpm) and moisture content of (13/26%) that required to obtain oil absorption index (2/60g/g) , bulk density (0/6g/cm3) , lightness (L*)(57/18) , antioxidant activity (35/14) and water activity (aW)(0/17).