Process of blanching

Blanching is a thermal process most often associated with solid food commodities such as fruits and vegetables. It is defined as a heat treatment given to plant material for inactivating enzymes and killing plant tissues to prevent enzymatic and microbial deterioration.

The aim of the process is to- prevent the deterioration of products which usually starts at the time of harvest. Enzymatic activity, which continues after harvesting, breaks down the plant tissue, and it is therefore important to inactivate any enzymes present.

Most of the quality attributives are less sensitive to thermal treatments than the enzymes systems within the product. This would suggest that blanching processes at higher temperatures and shorter time would result in increased retention of the quality attributes.

Other advantage of blanching especially for vegetables canning mainly to shrink the vegetable to obtain the correct fill weight in the can and to remove the gases from the intercellular spaces which would otherwise cause oxidation of the product, corrosion of the can and low can vacuum.

Blanching is required prior to dehydration of many commodities, since temperature associated with dehydration are insufficient to inactivate enzymes with the product and enzyme activity is not controlled by reduced moisture content.
Process of blanching