Close control of blanch time and temperature influences uniformity of product quality as well as energy consumption. For example, where a vegetable does require blanching prior to freezing, it is now being established that the blanch treatment required depends largely on the heat stability of those enzymes directly responsible for the main deteriorative changes in a given product during frozen storage. Hence energy may be wasted if the blanching conditions are loosely controlled to inactivate peroxidase enzymes, whereas the less heat stable lipoxygenases are the relevant enzymes to inactivate (20).
Accepting that there will always be variations in the vegetable raw material in terms of the physical and thermal properties, consistently uniform blanching conditions will result in consistent blanching effects. This may be less easy to achieve where one blancher is to be used to meet the requirements for a range of vegetable products. Consistently controlled blanching also permits the prediction of the degree of enzyme inactivation (21) and of leaching losses of various solutes using suitable models for water blanching (22).
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