The Department of Scientific and Industrial Research has released an account of the preparation of emergency rations in the form of dehydrated foodstuffs. These rations were designed and made when the result of a forced landing of an aircraft flying over polar regions may have to be faced. Having regard to the special circumstances for which the method described by the Department was designed it is perhaps not too much to say that it introduces as great a change in feeding the crews of airships as did Appert in feeding the crews of sailing ships a hundred and thirty‐five years ago. Appert's method did much to eliminate scurvy. This to prevent starvation and loss of life which the accounts of Polar expeditions have too often recorded. Dried fruits and dried vegetables have long been known and used. Milk powder and egg powder are now as well known. If these and tinned foods be regarded as ordinary rations they are too heavy and too bulky to be of use in an emergency such as may arise when a Polar flight ends in an unpremeditated grounding and the crew are left in a Polar desert to make the best they can of the conditions. It will be remembered that in May last the “Aries,” a British Lancaster airship, made a trip of some 17,000 miles. Much of this trip was in the Polar regions. The g eographical North Pole was visited and in the return journey the true position of the magnetic North Pole was ascertained in a 4,000 mile non‐stop return journey from White Horse, Yukon, to Shrewsbury. In view of possibilities an emergency ration had to be designed in which most of the food was in the form of hydrostatically compressed blocks of compounded and dehydrated foods. The compression reducing bulk; dehydration, weight; compounding ensuring variety. The rations so prepared had to be sufficient to feed nine men for twenty‐eight days. An account of the rations so prepared forms the subject of the report issued by the Department. These blocks consist of mixtures of dehydrated foods with added sweetening and flavouring materials where appropriate, so that each is a ready‐made meal requiring only the addition of water. They are fabricated into tablets of standard size (usually 2in. by 2in. by 0·9in.). They need only to be wrapped in high grade waxed films or papers and their standard size facilitates the assembly of mixed rations whilst very little space is wasted as compared for instance with circular cans. They are made by one of two processes—those containing dried foods of large particle size such as dehydrated meat or vegetables are made by compressing the mixture in a hydraulic press. The pressed block can be broken down easily in the hand. Where the particle size of the material is much finer, as with spray dried powders such as milk or egg, such compressed blocks would be very difficult to crumble, and furthermore lumps escaping crumbling would remain as unreconstituted lumps and mar the smoothness of the product. Thus they are prepared by casting the mixture hot into moulds with added molten fat. The block can be dissolved by boiling water. Many of the blocks containing milk powder may be eaten as sweets. Four kinds of menus from these blocks were prepared to relieve monotony of diet. Details of these are given in the report for four days. The total number of calories for each day ranges from 3,550 to 3,380. The weight of food per man in grammes from 715 to 704. Fat in grammes 213 to 177. Percentage of fat 30 to 25. The computed total nett weight was 393 lbs. Rations for two days can be packed in a standard four‐gallon can—gas packed if necessary—as a master container. Fourteen such cans would be necessary. These, together with immediate wrappings, would make a gross weight of 435 lbs. A most important consideration is weight. It is pointed out that the water extracted during the dehydration process would fill another seventeen cans! If light metal alloys instead of tin plate were used for the master cans a reduction of weight would be possible, but even a total weight of 435 lbs. is “very modest” compared with the weight of most emergency rations, even when the weight of master containers is excluded for the rations as drawn up provide for each man three normal meals per day. The Department refers to the theoretical aspect of the provision of a calorific level of 3,400 per day, with a total weight of 704 gms. per man. If the diet were made up of pure carbohydrate, pure fat and pure protein alone, then, using the factors 4·9 and 4 respectively as the number of calories derived from each gramme of food, a diet containing 25 per cent. fat would have an overall calorific value of 5·25 Cals/gm. a diet giving 3,400 calories, as in Day 3, would therefore weigh 647 gms. This is an absolute minimum below which it would be impossible to go. This figure takes no account of the residual water content of dehydrated foods of salt or minerals or roughage. The weight of 715 gms. achieved in practice includes, in addition to water and roughage, some 8 gms. of salt and 13 gms. of tea. It is therefore considered that, for a ration which gives three normal meals a day, it would be virtually impossible with the materials available at present to reduce the weight of the ration further. It may be added that a stove has been designed to burn motor spirit should it be possible to salvage any after a forced landing. It is considered that this type of food may be of great value for future polar expeditions. This is undoubtedly true whether aeroplanes be used as part of the equipment or not. It may be permissible to suggest that rations such as these would prove useful in land expeditions at a pinch. While in the case of a ship having to be abandoned in mid ocean the crew's chance of survival would obviously be bettered by having a supply of such concentrated rations in the ship's boats.
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