Effects of low temperature on the ascorbic acid content and quality characteristics of frozen strawberry

The effect of low storage temperature and freezing methods on ascorbic acid content and other qualitative characteristics of Iranian strawberries (Kordestan variety) were investigated. With two different types of freezing methods (slow at −20 °C and quick at −50 to −100 °C), three different temperatures and, following three months of storage, changes in colour, anthocyanin and ascorbic acid content, pH, acidity and sensory evaluation were tested. The major losses of ascorbic acid occurred during the first 15 days of storage and the percentage were 64.5, 10.7 and 8.9 at −12, −18 and −24 °C, respectively. No statistically significant differences were observed between the −18 and −24 °C and freezing methods in ascorbic acid losses, pH level on acidity content. In the slow freezing method, there was a statistically significant difference only in pH level, at all three temperatures. Therefore, the storage temperatures of −18 and −24 °C were best for preserving the qualitative characteristics (colour, texture, flavour and wholeness) of the strawberries.