Rheological Behavior of Yeast Paste from the Ethanol Industry

Abstract

Moist yeast is a byproduct of the ethanol industry with potential applications in the animal feed and food industries. Presently, knowledge of moist yeast's rheological properties is limited, despite it being crucial for the design and optimization of unit operations involved in the processing of this raw material. The work presented here is a study of the rheological behavior of yeast paste at different solid concentrations (0.15, 0.25, 0.35, 0.45, 0.55, and 0.64 g/mL) and temperatures (20, 30, 40, 50, 60, 70, and 80°C) using a concentric-cylinder rheometer. The experimental results were evaluated using four rheological models. The Power Law model was the best fit, demonstrating pseudoplastic behavior in all concentrations studied. In addition, the dependence of the flow behavior index and the flow consistency index of the Power Law model on temperature and solid concentration was also successfully modeled through a quadratic model and an Arrhenius-type equation, respectively.