ABSTRACT
Thermal treatments of foods can be dated back to prehistoric times when cavemen accidentally discovered the wonder of fire (and heat): the sensory quality of roasted animal carcasses was superior to the raw meats, and later the healthful effect of cooked foods was also appreciated. Frenchman Nicholas Appert, is credited as the one who started the canning industry even though he did not understand why canning techniques he invented prevented food spoilage. It took the genius of Louis Pasteur, a half century later, to discover the relationship between thermal processing techniques on a scientific basis. Thermal processes in modern-day food industry are more or less designed to destroy undesirable microorganisms and enzymes that are either harmful to human health or destructive to food quality during storage. Thermal processing of foods in food industry is generally referred to heating of foods packaged in hermetically sealed containers and pasteurization of liquid foods (may contain some particulates). It is carried out either continuously or batchwise in a consecutive process of heating, holding and cooling. Eating quality (which includes sensory quality) of foods is not always improved through thermal processing. Loss of flavors and nutrients, and changes of textures
and colors are recognized as the commonest complaints about thermally processed foods. As a result of this recognition, new thermal processes such as high-heat-shorttime (HTST) and ultrahigh-temperature (UHT) have been implemented in thermal processing of some foods, and non-thermal processes (electrical pulse field, high-pressure, ultraviolet light, and ultrasound) have also been developed and tested for certain foods for possible replacement of conventional heat processing (1). Aseptic processing and packaging further reduce heat damage to processed foods.
