PRESERVING FOOD

Hokitika Guardian, 25 June 1932, Page 6

PRESERVING FOOD

MODERN REFRIGERATION

METHODS DISCUSSED

WELLNGTON, June 18.

Modern refrigeration in the preservation of food was tile subject of a paper read this week before the Wellington Philosophical S.cety by Mr A. S. Mitchell, chairman of the technological section. The paper reviewed briefly the present position and reflected upon the future of refrigeration in the field of food preservation. It had reference more particularly to New Zealand.

In opening, Mr Mitchell discussed the historical side of his subject, saying that while in the abenec of such adequate physical and chemical data as were now available refrigeration had developed largely along empirical lines, there had been, nevertheless, great historic names familiar to science among those poineer researches a sure foundation for the industry had been laid. He mentioned a number of these, from Galileo and Robert Boyle to Clausius, Kelvin and Thomas Andrews. In the practical field, said Mr Mitchell, Jacob Perkins and Dr John Gorrie, both Americans, had been credited with the invention of the first practical refrigerating machines, although the sulphuric ether machine of James Harrison, of Geelong, had been built in 1855. HISTORIC VOYAGES. Mr Mitchell mentioned the historic voyages of the Strathleven, in 18(9, and the Dunedin, in 1882, which had been given a good deal of publicity recently in connection with the jubilee of the refrigerating industry. The type of machinery installed in those vessels, of British invention and manufacture, held, the field for many years, both ashore and afloat, until eventually superseded by the development of the ammonia compression machine by Carl von Linde of Munich, which although no doubt much improved in detail, wag the type still in in the majority of land refrigerating plants of the world even to-day. While refrigerating was but one of the many methods employed in the preservation of food, Mr Mitchell said, its (supremacy in the field for flesh products had never been seriously challenged, all competitive processes such as drying, smoking, pickling, and tinning, presenting their products in a coudtion with little resemblance to the original freshness, it had to be realised that there was a fundamental difference between flesh and fruit oi vegetable products, and the methods of treatment for preservations in each case. “Before proceeding further,’’ said 'Mr •'Mitchell," •'■‘it’i; 'assumed that to a New Zealand, audience it is unnecessary to stress the fact that from this country hitherto : (1) beef, mutton, and lamb, pork, butter and eggs in bulk, have been exported in a. frozen condition; (2) apples and pears have been exported at temperatures of 30-40 degrees F., although pre-war shipments of apples to South America were frequently in ordinary stowage, without refrigeration; (3) cheese has been exported at temperature,* from 40-55 degrees F., although both cheese and butter have been exported experimentally in vacuo recently, also without refrigeration; (4) eggs in the shell have been exported at temperatures of from 29-32 degrees F.

EXPERIMENTS WITH PROCESSES

Mr Mitchell proceeded to deal with processes which from time to time had threatened a revolution of the existing system. In this connection the effect, for example, of the reported Gas Storage Experiments of the British Food Investigation Board on Apples, had raised hopes in some minds that refrigeration would thus be superseded and that carbon dioxide either derived from the apples themselves or super-imposed upon the air of the storage rooms might displace the costly methods now employed. A system of vacuum packing had recently received a good deal of support and its progress was being followed with much interest, especially in the field of butter and cheese export, for which it was claimed to possess advantages. Within recent months two turther processes bad claimed public attention as possible rivals of existing methods. The first of these, which bore the endorsement of Dr A. W. Bowie, ol Gisborne, bad been reported upon b.v authorities in London, trial shipments having been sent from Gisborne last year. CLAIMS FOR NEW METHOD The second method mentioned made claims which, if verified, promised lo revolutionise the whole ol the lood preservation industry. It was the subject of an application for patent rights to the authorities in Holla-nd by Pape, formerly a South African dairy research worker. Among the claims made it asserted that from an insignificant power source comparable to the magneto of «• motor-car, rays, hitherto unknown to *cience, were disseminated, all food products within tho sphere covered being rendered immune from decay for periods in some cases exceeding 12 months. The claims of the inventor had been submitted to the chief of the Dutch Meat Inspection department, who, it was alleged, had given them a qualified approval. A bacteriological expert further supported the claims of hue terial inhibition within the sphere of the ray.;;.

“The foregoing challenges to existing method,* ol food preservation, Mr Mitchell said, “make it clear that while refrigeration is still -supreme in this field, the field is still open to any system "ha,e results r nproxiinale more closely to that ideal condition indistinguishable U'oiii the fn.i:)i. „<utorcri product "