Effect of drying method and cultivar on sensory attributes, textural profiles, and volatile characteristics of grape raisins

The sensory characteristics, texture profiles, and volatile compounds were investigated for grape raisins dehydrated by pulsed vacuum drying (PVD) and shade drying (SD) from three varieties (Thompson Seedless, Flame Seedless, and Munage). Results indicated that raisins dried from PVD were less brown, possessed stronger fruity aroma and flavor. Texture profile analysis revealed that samples dried by PVD displayed lower hardness and higher springiness, cohesiveness and resilience than the SD ones. In terms of the volatiles analysis, 34 compounds were identified including 7 alcohols, 7 aldehydes, 5 acids, 3 esters, 2 ketones, 5 terpenoids, 1 pyrazine, 2 furfurals, and 2 aromatic compounds. Raisins dried by PVD displayed higher relative content of esters and terpenoids, which contributes to the floral and fruity aroma. The drying methods were well differentiated according to the principal component analysis. The current findings indicate that PVD is an alternative promising technology for production of high-quality raisins.