Design of a solar dryer for small-farm level use and studying fig quality

In the mountain areas of south-east Morocco, farmers are engaged in the solar drying of figs using traditional processes. However, this practice leads to losses in quality. This study aims to improve this drying method by designing and studying the performance of a natural convection solar dryer and the quality of fresh and dried figs.

An indirect solar dryer was designed and its performance was studied. The TSS content, moisture, firmness and morphological parameters of fresh and dried figs were determinated.

The average difference (inside/outside) in the temperature of the dryer is +8.3°C. This will allow  a decrease in the mean drying duration from 10 days (traditional drying) to 4 days. This duration is signifi- cantly correlated with air humidity (R2 = 0.84) and temperature (R2 = 0.63). The relationship between the degree of dehydration (%) and time follows a polynomial model with a determination coefficient of 0.98. Fig-drying yield is 38.7% and dried figs have a high (TSS) content with 63.7% and a firmness of 6.03 kg/cm2. The water content was approximately 25.6%.

The solar dryer with natural convection designed in this study can be an alternative to traditional drying practised by small farmers in the mountainous regions of Errachidia.