TINNED FOOD.

Auckland Star, Volume LXX, Issue 124, 29 May 1939, Page 8

TINNED FOOD.

OPENED AFTER 114 YEARS.

The process of preserving food by cooking and sealing in airtight vessels, which are sulnseqiiently heated, was invented by a Frenchman named Appert at the end of the eighteenth century. He used glass jars. The introduction -of tins was made in England by Hall and Donkin about 1813; they supplied 23,779 tins of fifteen varieties of preserved meat and vegetables to the Admiralty in 1818 and in 1824 supplied a large number of tins of meat and vegetables to Sir Edward Parry for the provisioning of hie expeditions in search of the Xorth-west Passage. Two tins which were taken to the Arctic on Parry's third expedition in 1824 were brought ba-ck unused and taken again on the fourth expedition in 1526, and again returned to London unused. One tin contained four pounds of roast veal and the other two pounds of carrote and gravy, and they were kept in the museum of the Royal United Services Institution and the Xational Maritime Museum at Greenwich, respectively. The condition of the food and tins after 114 years i« of considerable scientific a/id practical interest, and the museum authorities gave permission for them to be opened and their contents examined. This has been done (reports the scientific correspondent of the "Manchester Guardian") by J. C. Drnmmond, W. R. Lewis, T. Macara, G. S. Wilson and H. L. Shipp, and their reports have l>een delivered to the food group of the Society of Chemical Industry. Eaten Eagerly by Rats. The meat was bright pink, like salmon, and rapidly lost its colour after exposure to the air. When a portion wae resterilised the pink colour returned. The meat wae in perfect condition, and the larger pieces looked quite like recently cooked veal. Some-of the veal fat was removed'and analysed. The composition was very similar to that of fresh veal ' fat. The most surprising result was that the \ 114-year-old veal fat had still 60 per cent I as much vitamin D (the vitamin which prevents rickets) as the fresh veal fat. It is evident that, canned food* may keep some vitamin activity for a very long time. Portions of the moat wore given to twelve adult rats for ten days. They were consumed with avidity and without ill-effects. An adult cat ate two and a half ounces of the meat at one meal without harmful effect. The tinned food supplied by Donkin and his partners to the Admiralty included a variety named "Soup a n<l Houilli." The word bully-beef was coined by seamen in their efforts to pronounce Houilli. Some other ancient preserved foods have been examined by the name investigators. They have analysed a portion of a cake of ••portable soup" which was probably made in 1771 and was carried by Captain Cook on his voyage of 1772-.1 and has since been in the museum of tlie United Services Institution. This cake is a flat rectangular slab about four inches square and marked with" a broad arrow. The material was very hard and I fractured like a piece of glup. It dissolved easily in cold Hater, and made a e'ear, pale yellow solution without emoll or taste. It contained 2'i per cent of protein, and appeared to be a desiccated clear broth prepared from meat and bones. It had remained virtually unchanged for 100 years. Science and Practice. An examination of the inside of the can which contained Parry's 1824 veal showed that one-half of it was still bright and the other half was corroded in patches. It appeared that the can had been scoured with sharp sand before filling, and the corrosion followed many of the scratches. The tinplate consisted of laminated wrought iron covered with exceptionally pure tin. Spectroscopic examination showed that it was at least 99.02 per cent pure, and was therefore probably Cornish tin collected from deposits in streams, which, is very pure.

The successful preparation of sterilised food on a large commercial scale half a century before Pasteur's discovery of the relation between bacteria and disease is a striking fact in the • history of science. The early food sterilisers believed that putrefaction was due to contact with the air itself, and this belief governed all practice until the end of the nineteenth century, long after Pasteur's work was fully continued. They had discovered by trials that the food must be sealed before it is sterilised by heat, but they did not perceive that this implied that the crucial change had nothing to do with the air itself. though it might be due to the contamination carried bv the air.

The practical men had provided the ■•cicntists with suggest ive facts, from which the correct deductions wen , made very tardily. One wonders how many fundamental scientific ideas are lying just under tlie surface of modern technical knowledge awaiting their Pastcurs. Some are probably there, and will presently he recognised by scientists free from the prejudiced perspective of traditional theories.