The effects of different drying methods on some physical and chemical properties of ‘Eksikara’ grape cultivar grown in Karaman region

Abstract

In this work, four different drying methods, namely natural drying in sun, natural drying in shade, natural drying in sun using a dipping solution and natural drying in shade using dipping solution were used to drying Ekşikara grapes growing in Karaman, Turkey. While aw values of all grapes were decreased during drying, total soluble solids content increased. The values of pH and total acidity in grape samples significantly increased during the drying period due to the increase in dry matter content. The results showed that all the drying treatments significantly increased the total phenolic content, total antioxidant activity, trans-resveratrol, organic acid and sugar compounds. Trans-resveratrol amounts were slightly higher in the samples dried in the shade and in the dipping solution treatment and decreased as the drying time increases. An increase in organic acid and sugar contents was observed depending on the drying time. The change of colour was comparatively faster in dried samples with dipping solution. It was found that dipping solution treatment (7 days) reduced the drying time by half when compared to the samples without dipping solution treatment (15 days). This result is important for the grape producers of Karaman/Turkey, where the drying period under sun generally take 15 days.