Drying of Distillers Spent Grain from Bourbon Production: Kinetics, Moisture Diffusivity, and Physicochemical Properties Analysis

Highlights Spent grain (DSG-B) from bourbon distilling constitutes a major disposal problem. Higher drying temperatures increased moisture diffusivity in DSG-B. DSG-B quality is unaffected by drying temperatures from 45°C to 70°C. Drying method impacts DSG-B properties compared to freeze-drying. ABSTRACT. The drying kinetics and physicochemical properties of wet distillers spent grain (DSG-B) derived from bourbon production were investigated to enhance the drying process and the utilization of the nutrient-rich by-product. The wet DSG-B was obtained by centrifugation of stillage, the main co-product of bourbon distilling. It was then dried at three temperatures (45°C, 55°C, and 70°C) using hot air drying. We assessed the physicochemical properties of DSG-B and calculated effective moisture diffusivity based on Fick's law of diffusion. The results revealed no significant differences in physicochemical properties across the drying temperatures; however, variations were observed compared to freeze-dried samples. The effective moisture diffusivity was 1.32×10 -9 (m 2 /s), 1.49×10 -9 (m 2 /s) and 2.38×10 -9 (m 2 /s) at 45°C, 55°C, and 70°C, respectively. The study provides insights into the effect of drying conditions on the physicochemical properties of DSG-B, with application in drying process optimization of DSG-B and enhances the utilization of bourbon distilling waste. Keywords: Distillers spent grain, Drying kinetics, Proximate analysis, Stillage, Thermal treatment.