Analysis of the reaction behavior of highly concentrated plant proteins in extrusion-like conditions

In processes such as extrusion processing, thermomechanical stresses are explicitly applied to proteins to develop novel structures, such as meat and fat replacers. However, due to the complexity of the processing conditions, little is known about the protein reactivity and structural changes under extrusion-like conditions. In this work, a specific closed cavity rheometer was used to analyze the decisive process parameters leading to significant change in the reaction behavior of a model plant protein system, i.e. vital wheat gluten, in defined extrusion-like conditions. The results show that the reaction behavior of the gluten proteins is a strong function of temperature, water content, shear and a step change in shear. Increasing water content in the range of 20% to 40% (w/w) led to significant increase in the reaction rates. Also the application of higher shear resulted in higher reaction rates, but mainly for degradation reactions.