Fruits are harvested before they reach eating maturity, in the period defined as tree maturity or harvest maturity. The quality is low because the apple taste and aroma do not develop in the fruit that is harvested too early. It is recommended to separate very large and small fruits and store medium-sized fruits specific to the variety. The storage life of very large fruits stored in the cold is shorter, and the economic value of very small fruits is low. Before storage, apples should be classified according to their color, size and maturity levels, and damaged, injured and defective fruits should be separated.
In commercial cold storage warehouses, apples are stored at 0 °C to 2 °C. It is noted that many apple varieties are stored for a long time at -1 °C to 0 °C and in an environment containing 85-90% relative humidity. Apple freezes at -2 °C. In our country, Golden Delicious, Starking Delicious and Granny Smith apple varieties are kept in the cold.
Golden Delicious apple variety is medium in size and large. Fruit flesh is white, hard, juicy and delicious. The outer surface of the bark is green and turns yellow as it matures. Storage life is 5 months in cold storage conditions at 0 °C and 90% humidity.
Starking Delicious apple variety is also medium-sized and large. Fruit flesh shows characteristics similar to Golden variety. The outer surface color of the bark is yellow-red and red. Cold storage conditions at 0 °C and 90% relative humidity, the storage life is 7 months.
Granny Smith apple variety is medium-sized and large. The fruit is bright vibrant green in color. It is a very high quality apple variety with white flesh, firm, very juicy and a distinctive pleasant sour taste. Cold storage conditions The storage life is 9 months at 3 °C and 90% relative humidity.
The proportional humidity level of the storage air is important in the cold storage of apples and it should not be allowed to change the humidity rate. 4-6% moisture loss in apples causes shrinkage, while the increase in storage temperature shortens the storage life, frost damage occurs in apples during storage at very low temperatures.
Apples that have a low tendency to brown, have a good taste and texture, and do not crumble when thawed are suitable for freezing. Apples should be edible, but not softened.
After sorting, the apples to be frozen are washed and after this process, they are peeled mechanically in special peelers and cleaned by removing the core houses at the same time.
Some pre-treatments are applied in order to prevent the slices from losing their texture as a result of freezing and also to prevent the color from browning. The most suitable method to preserve the color is to boil the slices in hot water or steam. Since boiling causes loss of taste and water-soluble substances, other methods can be used for the same purpose.The slices were cut in a solution containing ascorbic acid (0.5-2%), SO2 (0.01-0.05%), CaCl2 (0.1-0.5%) and sugar (10-40%), especially by applying vacuum, It is stated that the color can be adequately preserved by keeping it and freezing the solution after it is disposed of with the help of drainage. Apple slices prepared in this way are packaged and sugar syrup is added to it, or mixed with sugar at a ratio of 5 to 1, packaged and frozen. Frozen apple slices produced in this way are mostly used in apple bakery products such as cakes.