In thermal processing foods are heated for a number of reasons, the main ones being to inactivate pathogenic or spoilage microorganism. Other reasons include inactivation of enzymes.
In fruit and vegetable processing, thermal processing operations, such as blanching, cooking, pasteurization, baking, grilling and sterilization, convert the living into non-living tissues.
Numerous methods exist for thermal processing of foods. Some of these techniques included the use of steam injection, steam infusion, tubular heat exchangers, shell and tube heat exchanges, plate heat exchangers, microwaves heaters and radiofrequency heaters.
Optimization of thermal processing is possible, since the rate of destruction of spoilage microorganisms and enzymes is faster than the rate of quality deterioration.
While thermal processing of liquid food materials always results in biochemical changes, depending on sterilization time and temperature. These changes include the change in food color, which is associated with heat treatment of the food.
It also can alter the taste, aroma and texture, and can also lengthen the shelf life. A large number of the processes taking place in foods during heating are based on non-enzymatic browning i.e. the Millard reaction.
Food thermal processing
