Single- and multistage heat pump drying of protein

The pharmaceutical, nutraceutical, and food industries' main problems in drying are related to powder quality, low solvent removal rates, high production, and investment costs. The market success for a new powder depends on its properties and process economics. Consequently, the current challenges are the development of technologies for enhanced powder quality, low energy use, low cost, and minimum environmental impact. Heat pump fluidized bed multistage drying is a potential alternative to produce protein powder. This drying technology consists of atmospheric lyophilization in order to attain a stable structure and step up the temperature for evaporative drying to increase moisture removal rates. In addition, the multistage drying has to follow a strategic schedule that results in optimized rates and product quality. Seven protein drying runs were made in a laboratory-scale heat pump dryer designed and built for precise operating conditions. The raw materials and powders were characterized and the multistage drying trials were compared based on kinetics, color, density, and deformation. Hence, the specific objectives of this work were to compare performance of multistage drying, to identify ways of improving moisture removal, and to study the effect of drying conditions on powder quality.