Optimization of frozen sour cherries vacuum drying process

Abstract

The objective of this research was to optimize the vacuum-drying of frozen sour cherries in order to preserve health-beneficial phytochemicals, as well as textural characteristics. Investigated range of temperature was 46-74°C and, of pressure, 17-583 mbar, in a new design of vacuum-dryer equipment. The total solids, aw value, total phenolics, vitamin C, antioxidant activity, anthocyanin content, total colour change and firmness were used as quality indicators of dried sour cherry. Within the experimental range of studied variables, the optimum conditions of 54.03°C and 148.16 mbar were established for vacuum drying of sour cherry. Separate validation experiments were conducted, under optimum conditions, to verify predictions and adequacy of the second-order polynomial models. Under these optimal conditions, the predicted amount of total phenolics was 744 mg CAE/100 dw, vitamin C 1.44 mg/100 g per dry weight (g dw), anthocyanin content 125 mg/100 g dw, IC50 3.23 mg/ml, total solids 70.72%, aw value 0.646, total colour change 52.61 and firmness 3395.4 g. The investigated parameters had a significant effect on the quality of the dried sour cherries. © 2012 Elsevier Ltd. All rights reserved.