Abstract
Background: Rice bran is a rich source of proteins, dietary fiber and bioactive compounds. In the past, it was thrown as a waste or used as animal feed. Keeping in mind, the nutritional and health benefits of rice bran, an attempt is made to produce ready-to-eat snack product using twin screw extruder.
Methods: In the present study, rice flour, corn flour and deoiled rice bran mixtures were used for the production of twin screw extruded products with good nutritional value. The experiments were conducted by varying the proportions of Rice Flour (RF), Deoiled Rice Bran (DRB), moisture content of raw flours (13-17%), screw speed (275-375 rpm) and die temperature (100-140 °C) using central composite rotatable design. The composition of Corn Flour (CF) was kept fixed at 10% in all the experimental runs. Second order quadratic regression model fitted adequately in the variation. The significances of all terms in the polynomial were judged statistically by computing the F-value at probability (p) of 0.01 or 0.05.
Results: The physical properties like Lateral Expansion (LE) and Bulk Density (BD) were significantly affected by different process and machine parameters. Increasing feed moisture content results in a higher density and lower expansion while increasing barrel temperature and screw speed reduced density but increased expansion of extrudates. The optimum conditions obtained for the different variables were 17.73(%) deoiled rice bran, 13.94 (%) feed moisture content, 294.68 (rpm) screw speed and 123.83 °C barrel temperature to produce acceptable extrudates
Keywords: Extrusion, deoiled rice bran, extruder, response surface methodology, expansion
Graphical Abstract
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