History Nicholas Appert of France is credited to having invented food canning in 1810 to help feed Napolean's armies. Food was placed in a metal container, the container was sealed and heated. Today, canning is an important method of food preservation. The application of heat, or thermal processing, to destroy spoilage or toxin forming microorganisims is a safe way of preserving foods. Foods in containers are heated in retorts using steam for the most part, but hot water for glass jars or steam-air mixtures for plastic pouches are also used as the heating media.
Retorts can be batch or still type or continuous.
Modern retorts in commercial practice can process several thousand cans per hour. In order to speed up the rate of heating in the can, agitated retorts have been developed. Unless low-acid foods are thermal processed adequately, lethal toxin can be produced by Cl. botulinum spores. We employ thermocouples to measure in-can temperatures of food products during thermal processing. The thermocouples are connected to a computer equipped with software to record the temperatures inside of the cans.