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. At pH 4–6, most anthocyanins appear colorless. 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 who found that anthocyanin content of Assaria variety of pomegranate decrease significantly during 72 h storage at 4 _C.
prefreezing