ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Rheological and AFM Characteristic of Hydrolyzates Produced by Limited Enzymatic Hydrolysis of Soy Flour Extrudates

M. Witczak, A. Ptaszek, D. Žmudziński, K. Surówka, and M. Grzesik

Faculty of Food Technology, University of Agriculture, PL-30 149 Kraków, Poland

E-mail: rrwitcza@cyf-kr.edu.pl

Abstract: Effect of limited proteolysis of extruded soy flour on rheological properties and microstructure of the obtained hydrolysates was investigated. Flow curves with a controlled shear rate and timedependent curves with a constant shear rate were determined. The surface of investigated material was studied with atomic force microscope Quesant “Nomad” model. Rheological characteristics have been studied using a Cheng and Evans structural theory. Multiple exponential flow law was used to calculate non-Newtonian equilibrium viscosity. The shear stress was modified using structural parameter accounting for time-dependent effect. These studies have shown a significant influence of the enzyme used upon the rheological properties and structure of suspensions of hydrolysis products.

Full paper in Portable Document Format: 596ba491.pdf

Chemical Papers 59 (6b) 491–495 (2005)