| Abstract: | Extrusion processing has many useful applications in the food industry. The process yields low-cost texturized proteins which has great potential for growth on a world market. Most of the research in the area of texturization of vegetable proteins has focused on solving problems related to process control. These studies indicate that product development is more of an art than a science. The process becomes very unstable under the conditions necessary to texture protein ingredients. Very little definitive information is known about the rheological, thermal. and chemical interactions occurring in the extrusion process of various vegetable raw materials. An understanding of the effect of various interactions on the resulting extrudate will permit more precise control of product quality while minimizing energy inputs. Over-processing is expensive and usually produces inferior products. Research data should aid in maximizing extruder operating efficiency in the production of texturized vegetable protein foods with specific desirable characteristics from various raw materials. A high protein soy flour was subjected to controlled temperature, pressure, and shear rate in a viscometer similar in design to the Instron Capillary Rheometer. Initially soy flour was utilized, but the process can be applied to other oilseed isolates such as cottonseed meal. Physical and rheological properties of the extrudate were measured and correlated. These properties included extrudate hydration, thermodynamic activation energy. extruding viscosity. and extrudate stress-strain behavior. Results indicate a need for improved extruder designs for a wide variety of products from soy and cottonseed materials. |
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