Rehydration characteristics of freeze-dried strawberry pieces as affected by whey protein edible coatings

Abstract

This paper is about the use of whey protein isolate (WPI) edible coatings to improve the rehydration behaviour of freeze-dried (FD) strawberry pieces. First, the optimal ratio sample mass/volume of coating solution was optimised by determining the rehydration ratio, bulk density and nutritional quality of the samples. Coating time is also determined in coated samples by light microscopy. Second, the effect of changing the pH and the variation in temperature-time to denaturate WPI on rehydration characteristics was also evaluated. The rehydration ratio of strawberry pieces decreased with increasing the denaturation temperature and denaturation time, while it increased with increasing pH of the coating solution. Third, according to the rehydration curves, coating was not a single layer but small pieces attached to strawberry pieces. The soluble protein contents in water after rehydration confirm this conclusion. © 2011 The Authors. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology.