Effect of freezing method and storage on frozen cherry tomato quality

In this study, the effects of freezing methods and frozen storage on cherry tomato quality were studied. Four different freezing treatments; progressive freezing, individual quick freezing, static freezing and individual quick freezing after vacuum treatment were applied to the cherry tomatoes. Individual quick freezing has already been used in the industry for frozen cherry tomato production. Because of usability potentials for frozen cherry tomato production, progressive, static and individual quick freezing after vacuum treatment were chosen. While tomatoes were frozen at -20 °C in static and individual quick freezing, progressive freezing was done respectively at 0, -10 and -20 °C. 11 psi (22 inHg) vacuum applied for 10 minutes, then individual quick freezing was done at -20 °C in individual quick freezing after vacuum treatment. Samples were analyzed for methanol production related with pectin methylesterase (PME), polygalacturonase (PG), lipoxygenase (LOX) activities, lycopene, pH, titratable acidity, total dry matter, skin cracking ratio and color at raw material, 1., 2., 3., 4., 5. and 6. months of storage at -20 °C. During storage period, titratable acidity, pH, soluble solid and total dry matter were not shown great change. First month of frozen storage caused increase in methanol production related with PME activity. Similarly, first month of storage caused increase in PG activity except progressive freezing. Tomatoes frozen by individual quick freezing had the highest methanol production, PG activity and skin cracking ratio. Skin cracking ratio of tomatoes frozen by progressive and static freezing was found similar. Methanol production and PG activity decreased from first month of storage. LOX activity in first month decreased significantly compared to raw material. Statistically significant difference between LOX activities of tomatoes in 2., 3., 4., 5. and 6. months of storage was not found.