Three different drying methods (sun drying, hot air and solar drying) were investigated to evaluate their performance and effects on quality attributes of six crops. These crops included three fruit crops (grapes, figsandapricots)along with three vegetable crops (tomato, okra and jew's mallow). A solar collector was designed and used in the present study. Values of drying constant (K) and coefficientdetermination(R2) were evaluated for each of the aforementioned crops and the Fick's equation diffusion equation was applied. Consequently, the optimum time of drying was interpretated for each crop.
No significantdifferencescouldbetracedregardingdehydrationandrehydrationratiosofanyofthesixcropsdried by the three methods under study. Furthermore, losses in some chemical components (sugars, total and fixedacidities, and SO2) due to drying by different methods were insignificantforeachofthecropsunderinvestigation.On the other hand, severe destruction of vitamin C could be observed for all dried crops regardless the drying method applied as compared to their fresh correspondings. Microbial analysis exhibited higher bacteria and yeast and mould count (CFU/g) for almost all crops preserved by sun drying than their counterparts preserved by hot air and solar energy. The panelists preferred the colour of grapes, apricots, tomato and jew's mallow dried by solar energy and hot air than their correspondings dried naturally. On the other hand, no significantdifferencescouldbeobservedregarding scores given by the panelists for flavourandtextureforallcropsunderstudy,withjew'smallowbeingtheonlyexception and so it was less acceptable