Freezing of fruits
Enzymes in fruits can cause browning and loss of vitamin C. Because fruits are usually served raw and people like their uncooked texture, they are not usually blanched. Instead, enzymes in frozen fruits are controlled by using chemical compounds. The most common control chemical is ascorbic acid (vitamin C). Ascorbic acid may be used in its pure form or in commercial mixtures of ascorbic acid and other compounds. Some directions for freezing fruits also include temporary measures to control browning. Such temporary measures include placing the fruit in citric acid or lemon juice solutions, or in a sugar syrup. However, these latter methods do not prevent browning as effectively as treatment with ascorbic acid.