| Effects of varying screw speed, moisture content and feed rate on cottonseed meal de-gossypol process were studied using both single-screw and twin-screw extruder. Experimental results indicated that difference in . detoxification rule could arise between single-screw and twin-screw extruder or cottonseed flour and meal. Effects of screw configuration, mainly kneading blocks (KB) indicated that incorporation of KB, if appropriately set, could considerably reduce the residual free gossypol (FG) content. The length and position of KB significantly affected the de-gossypol results, while the spacing effect was marginal. KB parameters take effect as well. As for the de-gossypol mechanism, FG might react with several kinds of Amino Acid and with more than one binding site, ε -Amino Acid possibly the most important. In addition, the extrusion product fibrous texture of cottonseed protein was similar to that of soy protein.Through an experiential rheological model of protein product extrusion, flow simulation of single-screw extrusion indicated that different flow models led to different results. Isothermal and Newtonian flow model could reflect the true extrusion process to some degree though numerically different from the non-Newtonian, while the non-Newtonian, non-isothermal and temperature-undeveloped model experienced a fluctuation of extrusion variable at the beginning and stability as well after enough length of development zone, with values the same as those fully developed. In addition, effects of moisture on extrusion process were shown to be dominant, screw speed the less and dimensionless volumetric flow rate mainly affected the velocity distribution along the channel. With the viscosity, a distribution of small value near the wall and great in the midst of channel depth was assumed.Seen from the detoxification and flow simulation result, the screw extrusion de-gossypol method and numerical flow simulation of this extrusion process were proved to be effective.
|
PDF Full Text Request