Preparation and physical-chemical characterization of cashew raisins in a low-cost solar dryer

Abstract

Cashew is a very consumed fruit due to its sensory characteristics and because it is a fruit rich in vitamin C. Due to the high rate of perishability and losses in production, techniques are sought to increase the shelf life of the product, minimizing these losses. Among these techniques we have osmotic dehydration and drying. The objective of this work was to dry the cashew apple, previously osmotically dehydrated, in a solar dryer and to evaluate its efficiency by comparing it with the oven, through the construction of kinetic curves of drying and evaluation of the dehydrated product. Thus, sliced ​​cashew apples were osmotically dehydrated in syrups with 40 and 50 ºBrix, at 30ºC, followed by solar drying using a solar dryer with air circulation and an oven with air circulation with average temperature obtained in the solar dryer. The osmotic dehydration process was evaluated through weight loss, moisture loss and solid incorporation. An analysis of the physical and physical-chemical characteristics (pH, soluble solids, titratable acidity, vitamin C and color) of cashew nuts “in natura” and dried was carried out. Furthermore, the experimental data were fitted to the Page, Logarithm and Midili models. The Midili model was the one that best represented the drying kinetics, the solar dryer showed a shorter drying time and a higher value of ascorbic acid, being a low-cost alternative that delivers a quality product.