Optimization of the solar drying of wild pepper from Madagascar

Voatsiperifery is a wild pepper with a tail endemic to Madagascar. Traditional solar drying affects the quality of the dry product obtained. The main objective of this work was therefore to determine the type of solar drying suitable for voatsiperifery. The drying process must be optimized in terms of time quality and cost. To do this two prototypes of solar dryers operating with natural convection were designed one of direct type and the other indirect. The evolution of the water content of the product was followed during the drying process. The physico-chemical characteristics and the chemical composition of the essential oils obtained were determined before and after drying for a comparative study. All the tests carried out led to the choice of the direct prototype allowing to decrease rapidly the water content from 76% to 10% during 2 days. The direct drying allowed us to obtain an essential oil content of 14% dry basis and a piperine content of 0.6% dry basis. The return on investment for the use of the direct solar dryer is lower than for the indirect solar dryer.