Final answer:
Unblenched fruits and vegetables are more susceptible to freezer burn after freezing, which causes a mottled appearance but does not necessarily spoil the food. Wrapping food tightly and keeping the freezer at a low temperature can help prevent freezer burn.
Step-by-step explanation:
Fruits and vegetables that have not been blanched prior to freezing are more susceptible to freezer burn. Freezer burn occurs when water sublimates from frozen foods, leading to a mottled appearance. This process is not actually burning, but it can make the food look unattractive, although it's not necessarily spoiled. To minimize deterioration due to freezer burn, it is advisable to lower the freezer's temperature and to wrap foods tightly, limiting the space for water to sublime into.