Horticultural Products: Heat, Sugar and Solar Drying [46] (continued)

In the same year, the Chaffey brothers came to Victoria to initiate the irrigation of the lower Murray valley. Mildura and Renmark followed. So, too, did many foreseen and unforeseen difficulties. In 1893 the first general harvest was a good one, but transport was inadequate and harvested fruit was simply put on trays to dry in the sun. Gradually technological improvements followed; caustic soda dip, equipment such as stemmers, graders, and winnowers, cincturing of currant vines, packing sheds, and mechanization. By 1900 Australian demands for dried fruits were being met and export was anticipated.

Fruits dried either by the sun or by mechanical means are more acceptable products than vegetables dried similarly, probably because the vegetables are expected, more than the fruits, to be reconstitutable to the familiar forms met with on the dinner plate. Vegetables dried in the hot air tunnels which were standard before the Second World War regrettably gave results easily distinguished, to their disadvantage, from those obtained with fresh products. Tunnel drying was nevertheless all that was available when, at the beginning of 1942, it was evident that dried products would be required for service rations. So tunnel driers were introduced in a number of country districts of Australia to process carrots, potatoes and other crops. A great deal had to be learnt very quickly about an unfamiliar technology and CSIR and American expertise was made available to help Australian food technologists with the various combinations of time, temperature and humidity required, pre-treatment of the raw materials, and packing of the products in nitrogen. Nevertheless, some genuine innovations, especially in production engineering emerged from Australian industry. Much progress has been made since those days and conventional tunnel drying has been greatly improved by leaving the last few per cent of moisture to be removed by bin drying at lower temperatures. This technology, however, has languished and the special techniques for the drying of instant mashed potatoes, fluid bed drying, explosion drying, and even freeze drying have been introduced.

Australian Academy of Technological Sciences and Engineering