Concerning to the effect of precooling, it could be observed
that the treatments of cooling – citric acid combination were
lower in firmness, total acidity, ascorbic acid and anthocyanin
contents compared to uncooled treatments. Furthermore, precooling
treatments promoted decay in thawed berries. The pH
value raised to reach 4.22 in thawed berries. Since the color
and stability of anthocyanins are known to be influenced by
pH. As pH increases, color fades. Higher pH will lead to the
formation of the colorless carbinol pseudo-base and e subsequent
chalcone molecule which have a pale yellow color
(Coultate, 2002). At pH 4–6, most anthocyanins appear colorless
(Mazza and Miniati, 1993). Anthocyanin content reduced
by about 12.6% in cooled prefreezing berries in contrast with
frozen directly. However, these results are in general accordance
with that obtained by Miguel et al. (2004) who found
that anthocyanin content of Assaria variety of pomegranate
decrease significantly during 72 h storage at 4 C.