MATHEMATICAL MODELLING OF ANONNA MURICATA L. (SOURSOP) LEAVES DRYING UNDER DIFFERENT DRYING CONDITIONS

Abstract

In this study, the thin layer drying behavior of Anonna muricata (Soursop) leaves under three different drying methods; open sun, heat pump and oven drying methods at temperature of 40oC were evaluated in order to predict the best equation for the drying process from thirteen (13) existing drying Mathematical models. Fresh samples of the leaves were obtained and dried simultaneously under these drying methods and weighed at regular intervals until three consecutive weights were achieved. A precision weighing balance was used in measuring the change in drying weight of the leaves. The drying data; moisture loss and drying rate were obtained and converted to moisture ratio which were fitted to the thirteen mathematical models. The best fit model to describe the thin layer drying of Anonna muricata (Soursop) leaves was achieved based on the model with the highest correlation coefficient (R2), and lowest reduced chi square (χ2) , root mean square error (RMSE), Sum of Estimated Error (SEE) and Sum of Square Error (SSE).Modified Henderson and Pabis model, Hii et al and Hii et al mode were found to give the overall best fit from all the models examined for open sun, heat pump and oven drying method respectively. The results gave highest R2 values of 0.9941, 0.9843 and 0.9987, lowest values of RMSE of0.015102, 0.032891 and 0.010322, lowest values of SEE of 0.016641, 0.034435 and 0.012873 and lowest reduced chi square (χ2)values of 0.001991, 0.004805 and 0.040539, for open sun, heat pump and oven drying method respectively. Validation of the established model gave good agreement between the experimental and predicted variables, therefore, Modified Henderson and Pabis, Hii et al and Hii et al equation could be used satisfactorily to predict thin layer drying of Anonna muricata (Soursop) leaves for open sun, heat pump and oven drying method respectively.