Effect of coating on post-drying of freeze-dried strawberry pieces

Although the color, flavor and taste of freeze-dried (FD) strawberries pieces are very good, texture collapse after rehydration limits the application of FD strawberry pieces in liquid carriers. In this work, the effects of coating the freeze-dried pieces and the drying method after coating are investigated. The best formula for the coating solution is found to be: whey protein 10%, glycerol 3%, lactose 10%. Color of strawberry pieces can be protected to some extent by adding Na+ and β-Cyclodextrin (β-CD) in the coating solution. The best proportions of Na+ and β-CD were 3 mg/ml and 0.5 mg/ml, respectively. Coated freeze-dried pieces of strawberry were dried in a spouted bed. The rehydration characteristics of the coated strawberry pieces were found to be influenced by the coating time as well as the drying conditions used.