ABSTRACT
Extrusion cooking is a high temperature short time shear process used to modify food structure, imparting texture. Successful use of single-screw extrusion processing technology to manufacture texturized food products in the food industry dates back to the 1960s, but the introduction of double extrusion and the use of twinscrew extruders made possible the creation of extrusion texturized proteins in the late 1970s (Atkinson 1970; Kinsella 1978; Harper 1979). Better understanding of the extruder con•guration parameters necessary for developing a layered and meatlike texture with consistent characteristic properties made soy and other vegetable proteins the •rst successful and most widely available textured protein food (Cheftel, Kitagawa, and Queguiner 1992). Texturization is the unraveling of the globular structure of native proteins, accompanied by breakage of intramolecular bonds, and re-alignment of disul•de bonds, with the use of mechanical shear, heat, and pressure as requisites (Bhattarcharya and Padmanabhan 1999; Shimada and Cheftel 1988). The use of food protein sources, including dairy products, in texturization remained in the developmental stage up to the recent past due to dif•culties associated with
Extrusion Processing of Proteins ........................................................................... 275 Extrusion-Induced Changes in Proteins ................................................................. 278
Thermal Gelation of Globular Proteins ............................................................. 279 Nonthermal (Cold) Gelation of Proteins ........................................................... 281
Thermal Extrusion of Proteins ............................................................................... 282 Nonthermal (Cold) Extrusion of Proteins ..............................................................285 Extruded Whey Protein Products ...........................................................................286
