Drying of Carbohydrate and Protein Solutions

Drying behavior of a single suspended droplet of various protein and carbohydrate solutions was investigated experimentally For small molecular weight carbohydrates such as sucrose and glucose, the constant-rate period was observed, which was followed by the falling rate period characterized as the “regular regime”. During the falling rate period, the drying rate was very low due to a sharp decrease of the water diffusion coefficient with decreasing water concentration. No remarkable constant-rate periods were observed for large-molecular carbohydrates and proteins. This is because the water diffusion coefficient is low even at high water concentrations. The drying curves of bovine serum albumin, skimmilk and model-food liquid solutions were found to be predicted by a computer simulation with the concentration dependent water diffusion coefficient of maltodextrin of dextrose equivalent = 11.The experimental investigations on the ethanol and enzyme retention during drying indicated that the ethanol is lost during the constant-rate period and the enzyme inactivation occurs during the constant-rate period (regular regime).