A. THERMAL PROCESSING IN GENERAL Thermal processing implies application of thermal energy at suitable thermal potential, namely temperature to a reacting system. Thermal effects on chemicals, biochemicals and biological materials have long been recognised. Existence of these effects has been used to the advantages of many industries. Thermal activation of chemical reactions and biochemical reaction constitutes a very fundamental process in chemical and biochemical technology. Polymerisation reactions, hydrolysing reactions, oxidation and reduction reactions are few examples of many important processing reactions which may involve thermal processing. In active living tissue, many metabolic reactions can proceed appreciably at room temperature, causing undesirable alteration in the tissue. Low temperature storage has the basic objective of arresting the various reactions which may cause spoilage and which proceed at higher temperatures. With active proteins like enzymes and living tissue, denaturation and functional inactivation can occur rapidly at processing temperatures. Sterilization of microorganisms, pasteurisation of milk are specific examples of this type of thermal processing.