M Moradi - Assistant professor of biosystems engineering of Shiraz University
M Niakousari - Associate professor of food engineering of Shiraz University
A Etemadi - M. Sc of food engineering, Shiraz Serum Co

This research, presents mathematical modeling of drying process of Aloe vera slices with dimensions of7×4×0.5±0.1 cm. Peeled Aloe vera slices with the initial moisture content of 5750% (d.b) were osmosed for 5hours in NACL solution of 10% and temperature of 40 °C at a constant solution to fruit ratio of 5:1. Osmosedand unosmosed Aloe vera samples were hot air dried at 55, 70 and 85°C with different air flow rates of 0.015,0.036 and 0.054 m3/s for 13200s. The moisture content of Aloe vera samples were measured over differentintervals of drying time (1200, 2400, 6000, 9600, 13200s) for each experiment. The experimental results wereused to obtain two different dimensionless models based on Buckingham’s pi-theorem for both drying methods.To this end, three independent π terms were identified and then the relation between dependent π term and eachindependent π term was sought. Finally, the dimensionless models incorporating the effect of all the independentπ terms on the dependent one derived and evaluated. The RMSE, (R2), MRD and MBE for the modeling ofosmotic-convective drying method were calculated as 0.0185, 0.99, 0.05 and 0.034, respectively. Also thesestatistical parameters for the convective drying method were as: 0.027, 0.98, 0.061 and 0.051, respectively.Therefore the dimensionless models could predict the moisture content of Aloe vera samples during drying,properly.

Aloe vera, Osmotic-air drying, dimensionless model