Quality attributes of some fruit and vegetable crops preserved by three different drying methods

الملخص EN

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, figs and apricots) 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 coefficient determination (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 interpreted for each crop.

No significant differences could be traced regarding dehydration and rehydration ratios of any of the six crops dried by the three methods under study.

Furthermore, losses in some chemical components (sugars, total and fixed acidities, and SO2) due to drying by different methods were insignificant for each of the crops under investigation.

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 corresponding.

Microbial analysis exhibited higher bacteria and yeast and mound 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 color of grapes, apricots, tomato and Jew's mallow dried by solar energy and hot air than their corresponding dried naturally.

On the other hand, no significant differences could be observed regarding scores given by the panelists for flavor and texture for all crops under study, with Jew's mallow being the only exception and so it was less acceptable.