Prediction of optimal conditions of infrared assisted freeze-drying of aloe vera (Aloe barbadensis) using response surface methodology

The present study illustrates an extensive experimental study on infrared (IR) assisted freeze-drying of aloe vera (Aloe barbadensis) coupled with statistical analysis. A 'three parameter three level' face centered central composite design (FCCD) has been employed to develop multivariate regression models in order to evaluate the influence of process parameters on the quality of the freeze-dried aloe vera powder. Optimal freeze-drying conditions of 8.5 W/g IR power, 80.24 degrees C product temperature and 6.67 h drying time have been established corresponding to minimum moisture content of 3.49%, maximum wettability of 52.84 s and maximum yield percent of 3.87 through response surface methodology (RSM). Separate validation experiments at the derived optimal conditions ascertained the predictive ability of the developed model equations. The outcome of this study would contribute to development of technical capabilities for the design of freeze-driers applicable to such high valued medicinal herbs. (C) 2011 Elsevier B.V. All rights reserved.