Twin‐Screw Extrusion Texturization of Acid and Alkali Denatured Soy Proteins

Abstract

Effect of pH on functional characteristics of soy protein was investigated by modifying soy flour through acid (HCI) or alkali (NaOH) addition. Acid-and alkali-treated proteins were evaluated and texturized by twin-screw extrusion. Products were analyzed by rheological, functional, and ultrastructural methods. Acid-modified texturized protein had little expansion, increased peak force, increased work of shearing, and a nonoriented fiber arrangement. Slightly alkaline extrudates had increased rehydration but poorer texture. Stronger alkaline treatment resulted in denser products with high peak force measurements, which disintegrated when extrudates were rehydrated. The physicochemical state of soy protein, particularly conformation and protein-water interactions as affected by pH, may influence expansion of textured products and development of plexilamellar structure.

Effect of extrusion cooking on structure and functional properties of pea and kidney bean proteins

“…WHC is mostly in¯uenced by protein±water interactions, water±water interactions and physical capillary actions. 16 Probably the greater WHC of the extruded samples was due to a primarily physical retention of water by capillary action in the new structure formed by aggregation of proteins These results are consistent with those of Narayana and Narasinga Rao, 36 Bencini 37 and Gujska and Khan 29 with other bean¯ours. The water solubility indices of both extruded peas and kidney beans increased signi®cantly with respect to the raw seeds.…”

Rheological characterizations of texturized whey protein concentrate-based powders produced by reactive supercritical fluid extrusion

“…However, WPs with a higher degree of aggregation were found to have increased viscosity due to the aggregates greater effective volume which could entrap more water than the individual WP molecules (Firebaugh, 2004). These findings are similar to those of texturized soy protein studied by Dahl and Villota (1991) and Fleming, Sosulski, Kilara, and Humbert (1974). Their results indicated that the viscosity of soy proteins increased markedly after proteins were modified by the alkaline treatment.…”

Physicochemical changes in whey protein concentrate texturized by reactive supercritical fluid extrusion

“…The effects of pH modifications during extrusion process on WP reactivity and functionality of final products have been reported (Amaya-Llano et al, 2007;Dahl and Villota, 1991;Martinez-Serna and Villota, 1992;Onwulata et al, 2006;Law and Leaver, 2000;Monahan et al, 1995;Walsh and Carpenter, 2001). Their studies showed that conformations and protein-protein interactions of WPs were strongly affected by pH.…”

“…The tWPC samples exhibited the ability to impart a wide range of viscosities by varying protein concentrations. This corresponds to stronger protein-protein and hydrodynamic interactions among particles with an increase in solids in the system (Dahl and Villota, 1991).…”

“…The resulting products had a fibrous structure and could be used as meat alternatives. Acidic treatments, on the other hand, showed higher protein solubility and produced non-oriented fiber arrangement of extruded proteins (Dahl and Villota, 1991;Onwulata et al, 2006). Queguiner et al (1992) also reported that the microparticulated whey protein isolate (WPI) could be obtained by extrusion at acidic pH (pH 3.9).…”