Enzyme Retention During Drying of Amorphous Sugar and Carbohydrate Solutions: Diffusion Model Revisited

Abstract

Enzyme retention during drying of amorphous sugar and carbohydrate solutions was investigated based on the diffusion model. As the water diffusion coefficient decreases sharply with decreasing water content, there is a period where the water content decreases slowly while the sample temperature is high. The enzyme activity is lost in this period. However, as enzymes become stable at lower water contents, high enzyme retention is possible when the drying condition is tuned. The diffusion model with the heat balance equation and the inactivation rate equation was able to describe the experimental data reasonably. Various sugars tested (glucose, xylose, sucrose, trehalose, maltose, maltodetrin) showed similar enzyme retention behavior except for maltodextrin. Lower enzyme retention of maltodextrin is found to be due to lower drying rates.

Keywords:

• Enzyme inactivation
• Sugar
• Water diffusivity