Experimental study on the optimized technological parameters for freeze-drying of aloe

The objective of study on aloe freeze-drying is to determine the optimized technological parameters in the drying procedure, in order to increase drying efficiency and quality of aloe dry products. Through single factor experiment and second order regression orthogonal experiment with four factors under five levels, the effects of drying chamber pressure, board temperature, temperature decreasing rate and aloe thickness on drying time were investigated, and a mathematical model describing the relationship between drying time and influence parameters was developed. Under consideration of higher drying quality of aloe dry product the optimized technological parameters for aloe freeze-drying with 6～9 mm thickness were obtained by means of nonlinear optimized theory and method, and these parameters were as follows: drying chamber pressure 108 Pa, board temperature 38～39℃, temperature decreasing rate -0.47～-0.35℃/min and drying time was 6～7 h.