Meat Preserving: Heat Processing Introduced (continued)

At first the sanitary cans were processed in boiling water baths, i.e., at 100^oC (212°F) or in brine baths at higher temperatures, as had been done since Stefan Goldner introduced them in 1841. At these higher temperatures, however, the lighter tinplate tended to explode but the steam pressure in a retort prevented this and it was not long before retorting became general. The steam pressure vessel, or retort, is often said to have been introduced by the American, A. K. Shriver, in 1874. In fact, William Hogarth of Aberdeen had been using 'high pressure steam' since 1837 [35] and when, in the wake of the Royal Navy preserved meats scandal, the Admiralty set up its own cannery in 1856 at Deptford, it too used retorts.[36] This method of heating came to Australia from Britain and was used in 1867 by the Ballarat Meat Preserving Company[37] and in 1870 by the Hogarth Australian Meat Preserving Company at Oakey in Queensland .[38] An 1898 photograph of the equipment in use at the rabbit cannery at Compton, near Mount Gambier in South Australia, shows modern retorts with pressure gauges and safety valves.[39]

Prescott and Underwood[40] at the turn of the century effectively laid the foundations of the bacteriological control of heat processing but for most canners retorting remained a question of establishing the length of time required at this retort temperature for that product in a can of such and such a size. It was not long, however, before the application of Prescott and Underwood's work led to the design of 'in can' thermometers and the measurement of rates of heat penetration for different products and hence to the establishment of specific heating times for specific products in specific can sizes at specific steam pressures, i.e., specific temperatures.

At first retorts were operated manually and the canner was effectively in the hands of the retort operator, whose devotion or otherwise to duty determined the efficiency of the process and the safety of the products. This was so in Australia for almost the entire industry until the Second World War. Nevertheless, the century 1840-1940, which opened with the beginning of Australian canning, ended with an industry which for decades had been producing canned meats, fruit products, and some vegetables, with safety if not in the most modern way.

A modern Australian canning industry dates from about 1942. It was 'called into being almost inadvertently like so much during the war, but built on a foundation of sound technology provided by the DFP* and American experts'.[41] This is very largely true because so many of the canners were 'meat and jam men' who knew little of other canned products, notably vegetables and the specialty products required by the U.S. armed forces. There were exceptions, however, for Edgells had been canning vegetables since 1926.

* CSIR Division of Food Preservation and Transport.

Australian Academy of Technological Sciences and Engineering