Cellular disruption and its influence over the drying kinetics of brewer´s spent yeast biomass

Abstract

Spent yeast biomass is one of the residues of brewing. It is specifically the second-largest residue from brewing industry. Most of the spent yeast is sold at low prices, or disposed as waste or used as animal feed. Spent yeast biomass is predominantly composed of proteins, and it has a high biological value, being an excellent source of high-quality protein, comparable in value with soy protein. Therefore, spent yeast biomass has great potential for use in foodstuffs for human consumption. The objective of this work was to evaluate the influence of cell rupture over the drying kinetics of spent yeast biomass using mathematical models (Lewis and Page). Also, to verify the influence of cell rupture method over the amount of protein. The cellular rupture was performed by two methods (chemical method and physical method: ultrasound). The drying process was performed by freeze-drying, and the parameters of the models were obtained using the non-linear regression (Generalized Reduced Gradient Nonlinear Optimization Code). Mathematical models of drying kinetics showed a strong correlation with the experimental data, R² > 0.96. The disruption process did not significantly affect the drying time and protein content. But the cellular autolysis improves the protein digestibility since the proteins will be totally available to the digestive enzymes and also increase the bioavailability of nutrients.