Optimization of combined drying (osmotic-hot air) of aloe vera slice using response surface methodology

The aim of this study was to produce dry aloe vera slice by osmotic-hot air drying method and to investigate the effects of this method on texture, color, shrinkage, water re-absorption ability and water activity. The studied variables included precooking time (5, 7 and 10 minutes), drying time (8, 10 and 12 hours) and drying temperature (40, 50 and 60 ° C) using the response surface method in the form of a central composite design. It was examined with six replications at the central point. The results showed that increasing the temperature to 50°C increased the hardness of the texture, but further increasing the temperature reduced the hardness. The rate of rehydration was affected by drying temperature. With increasing temperature, the rate of rehydration in the samples increased. However, changing the pre-cooking and drying process time had no effect on the amount of this parameter. None of the studied independent variables had a significant effect on water activity. Optimization results showed that pre-cooking for 10 minutes and drying at 53.93°C for 8 hours will produce products with the best characteristics.