Effect of freeze drying method on drying characteristics, colour and rehydration ratio of some apple varieties

Abstract

This study investigated the effect of the freeze-drying method on drying characteristics, color, and rehydration ratio of Gala, Granny Smith and Starking apple samples. Experimental results showed that the drying rate decreased with increasing drying time and decreasing moisture content of the samples. All color parameters of fresh Gala, Granny Smith and Starking apple samples were affected by freeze-drying. Freeze drying caused a decrease in L* and α° values, while a*, b* and C values increased. The highest rehydration rate value of 4.673 was obtained from Gala apple samples.