analysis results indicated that drying method ( p < 0.05) had
a significant effect on the thickness shrinkage of the final product.
Since regular FD sample was not predehydrated, structural
rigidity was created during the freezing stage of the drying
process. This rigidity prevented collapse of the solid matrix after
drying (Mujumdar, 1995). The thickness shrinkages were
5.9% and 11.5% for the regular FD samples with and without
acid dip, respectively. Compared to regular FD samples,
SIRFD samples experienced more thickness shrinkage for
both the undipped and dipped samples. Furthermore, more
shrinkage was observed with 40% weight reduction in predehydration
than the 20% weight reduction. For example, for the
undipped banana slices, 40% weight reduction samples had
33.6% thickness shrinkage as compared to 23.1% for the
20% weight reduction. This is due to the fact that more moisture
was removed from the sample during the predehydration
stage and also longer drying time required to obtain 40%