The main purpose of this study was to investigate the effects of
abrasive pre-treatment and of air drying conditions (i.e. temperature)
on the quality properties of raisins, with the aim of produce
minimally processed high quality raisins. We then compared the
results with those relevant to raisins obtained by grape pretreated
with alkaline ethyl oleate solution and untreated raisins.
Moreover, in order to represent the observed change in moisture
during drying experiments, data of moisture ratio were fitted
using empirical models available in the literature.
Since shrinkage influences drying and consequently rehydration,
it has to be taken into account in mathematical modeling of
such processes. Several types of models predicting volume changes
are also available in the literature (Brasiello et al., 2013; Khalloufi
et al., 2009; Mayor and Sereno, 2004). Some empirical models
were here tested to verify their ability to represent experimental
data of shrinkage volume during drying.