Comparison of Conventional and Dehumidified Air-Assisted Spray Drying of a Cellulolytic Enzyme Preparation Obtained from a Pleurotus sp. Culture

Liquid enzyme formulations are characterized by high water activity, which may adversely affect their storage stability and shelf life. Therefore, their powdered form can significantly improve enzyme stability while facilitating handling, dosing, storage, and transportation. To date, no studies have reported powder production containing cellulolytic enzyme preparations derived from Basidiomycota fungi. This study aimed to evaluate the potential of spray drying of cellulolytic enzyme preparations derived from submerged cultivation of the yellow oyster mushroom (Pleurotus citrinopileatus) and the pink oyster mushroom (Pleurotus djamor). In addition, the impact of conventional high-temperature spray drying (SD) and dehumidified air-assisted spray drying (DASD) to enable lowering of the drying temperature on the cellulolytic activity of the obtained powders was assessed. The obtained powders were comprehensively characterized for physicochemical properties, including moisture content, flowability, particle-size distribution, and particle morphology. In addition, biochemical analyses were performed to determine cellulolytic enzyme activity before and after spray drying. For both drying methods, obtained powders were microbiologically stable (water activity < 0.3) and exhibited good quality characteristics. The drying technique showed no statistically significant effect on enzymatic activity, as confirmed by the plate assay, while producing powders with comparable physical properties. Consequently, conventional high-temperature spray drying (SD) is an adequate method for stabilizing these cellulolytic enzymes, eliminating the need for the less economically reasonable dehumidified air-assisted technique (DASD).