This paper also discusses improvements in canning process including: traditional batch still retort, continuous retort, direct flame thermal process and finally aseptic thermal processes.
Canning refers to the process of commercial sterility of foods achieved through sealing and sterilizing foods in airtight containers mainly to kill microorganisms and preserve them for a specific period of time. The canning process is designed mainly to eliminate the spores of the bacterium, Clostridium botulinum. Clostridium botulinum is a toxin producing anaerobic bacteria that causes botulism. Canning is therefore a sterilization process requiring heating temperatures greater than 100o C (Karel & Lund, 2003). C. botulinum is however not viable under acidic conditions lower than pH 4.6 (McWilliams, 2012). It is therefore important to note that the time temperature regime for sterilization of foods are mainly influenced by several factors including acidity, type of microorganisms found in food, the size of container, the nature of food and the heating method. Different processes are involved in conventional canning operations including food preparation, container sealing, container sealing, and heat treatment and finally cooling.
Several methods of accomplishing thermal process in canning have been developed overtime. The different thermal processes were mainly based on the principles of heat transfers. The most important principle governing these developments and improvements was the need to increase production outputs while maintain the quality of the food products in terms of nutritional and safety (Karel & Lund, 2003). In this respect, many developments have concentrated in improving heating rates through efficient heat transfer methods. This has seen advancement in terms of equipment design to aid effective transfer of heat in food within the shortest time possible while preserving its quality.