Experimental characterisation and modelling of thin layer direct solar drying of Amelie and Brooks mangoes

Direct solar drying characteristics of Amelie and Brooks mangoes were experimentally determined using a solar dryer made up of four trays and used under weather conditions of fruit harvest period. Direct solar drying curves were established, fitted using 10 mathematical models and simulated with a direct solar drying model. Effective diffusivity, drying rates and drying efficiency were estimated for each drying day and each variety. Results showed that at least four days were necessary to reach the range of preservation water contents. Drying curves depended on variety and were suitably fitted by “two-term” and “Approximation of diffusion” models (with R2≥0.9888, RMSE≤0.0283, E≤9.1283% and χ2≤1.3314×10−4). Drying rates and drying efficiency significantly decreased with the number of drying days (respectively between 0 and 0.15gkg−1s−1 and between 0 and 34%) and were very close for the two varieties. Diffusivity weakly varied with variety and strongly decreased with the number of drying days between 2.7906×10−11 and 1.8489×10−10m2/s. Drying kinetics were suitably simulated by the direct solar drying model (with: Amelie: R2=0.989 and E=7.623%, Brooks: R2=0.9924 and E=4.961%). The final water content was about 24.83% for Amelie and 66.32% for Brooks and Amelie was the most suitable variety for direct solar drying.