Comparison of Convection and Vaccum Drying on Quality of Formulated Cornelian Cherry Leather (Pestil)

Cornelian cherry is a seasonal fruit which has the durability potential after harvest for 2 to 3 weeks. One way for keeping and increasing shelf life of fruit is preparing fruit leather (pestil). The aim of the present study was to investigate the different drying methods on quality of the formulated cornelian cherry leather (pestil). in the current study, effect of three different formulations (1% salt, 2% sugar, the mixture of 2% salt and 4% sugar) and control sample were investigated in two kinds of dryers (hot air dryer and dryer under vacuum) at the constant pressure of 200 mb in 55° C, 65° C and 75 ° C. Then drying curves, effective moisture diffusivity, total anthocyanin content, hydroxymethyl furfural, color and sensory properties of the prepared samples were evaluated. The results showed that the highest anthocyanin content and the lowest hydroxymethyl furfural accumulation and color changes were observed in vacuum dryer samples. Comparison of the treated samples in both dryers also showed that the control samples were the most favorable in terms of chemical and physical properties and the samples formulated with a mixture of 2% salt and 4% sugar were the most unfavorable. According to the drying curves, the samples formulated with a mixture of 2% salt and 4% sugar had the lowest and the control sample had the highest drying rate. Organoleptic properties showed that the best formulation was 2% sugar and 2% salt and 4% sugar formulation. According to the results, vacuum drying enables some distinctive characteristics such as higher drying rate and effective moisture diffusivity, lower oxygen medium and activation energy and hence high quality and nutritive dried samples. Thus among the selected methods for drying, vacuum dryer was more suitable.