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When men still alive today were young, not a single cargo of chilled or frozen meat, of fruit or of dairy produce from the Southern Hemisphere, had been landed in this country. We have, that is, lived in the last generation through a dietetic revolution which has left us to a large and increasing extent dependent on foodstuffs grown at the ends of the earth and consumed weeks or even months after they leave the places of their origin. Fifty years ago Australia was importing butter, and a century ago the first cow was imported into New Zealandwhere there are today more cattle than men. This change in the balance of trade has created a series of new problems in practical science. Some of these have been solved in part, others remain impregnable, and all urgently call for solution for every year, and almost every month, damage to cargoes is suffered that has its origin in our imperfect knowledge of how to submit perishable goods to the ordeal of prolonged ocean carriage. Beef, to take an obvious example, is hard to bring satisfactorily from Australia. There are two methods by which meat may be preserved, freezing and chilling. The same installation is used in both cases, but for the former, the machine requires to be more powerful, since the temperature of the meat must remain well below 32 degrees F. Mutton lends itself perfectly to freezing, but beef, owing to structural and other causes, is deteriorated if frozen. The tissues are ruptured by expansion, and so, when the meat is defrosted, much of the nutritive liquid escapes. It is possible, that this problem of drip may be solved. It is also possible that beef from Australia may be transported to Europe in a chilled not frozen state. Experimentally this has already been achieved, but much remains to be done before small scale experiment can be converted into current commercial practice. When it is remembered that there is available in Australia land which would feed a further seven to ten million head of cattle, the importance of the investigations now being conducted into means of transport will be understood. The ocean carriage of fruit involves inquiries equally fascinating and, perhaps, less known. An apple or an orange is not killed by being plucked, but continues to live and breathe, that is to say, to absorb oxygen from the air and yield in its place carbon dioxide. In consequence, a ship's hold packed with fruit would quickly resemble a Black Hole of Calcutta were not certain precautions taken. The crowded living cargo threatens to suffocate itself, and the remedy lies in lowering the temperature of the fruit so that it may breathe more slowly, and in the provision of adequate ventilation. Cold, and to a certain extent the expired gas, CO2, itself, lower the rate of livingthat is to say, the rate of chemical change, so that the fruit ripens more slowly. It is in this state of delayed ripening that apples from Australia or oranges from South Africa can be brought to this country without damage. Stated in this way, the problem sounds simple enough given some degree of cold and ventilation, all will be well. As a matter of fact, the limits of temperature and of ventilation within which it is permissible to move are narrowed by both engineering and biological considerations. Living matter does not suffer coercion gladly or passively, and the attempt to delay ripening, though it undoubtedly succeeds, does not leave the fruit at the end where it would be if it had ripened normally. The sequence of chemical change is different flavouring substances abnormal in character or in amount are apt to be produced, and the problem of successful storage is to hit upon that combination of temperature humidity and ventilation, which will in the end present the product to the palate of the consumer in a state as near to the normal as may be. Fruit, moreover, has its recognisable storage diseases, and, though much advance has been recorded in recent years, losses are still suffered regularly. As an example of the tricks that can be played with plants, it may be mentioned that a rose bush, just budding, can be kept at its freezing point and its growth arrested. Then, if it is sheltered under a hothouse roof so that light shines upon it continuously, it will bloom to perfection many months later, when its temperature is allowed to rise. Roses in December arc, in fact, a practical proposition. The stowage of fruit naturally requires particular care. On banana boats, for instance, the chambers are subdivided into pens by portable rails supported in special stanchions, and from the air trunk access may be had to the bananas for inspection during the voyage. To check the danger caused by bulging cases it is sometimes the practice to fit battens around the case ends of thickness equal to the amount of bulge, thus preventing pressure on the fruit itself when the ship rolls. Mere ventilation without refrigeration is sometimes found to be adequate. Provided a good, regular circulation of air is secured, fruit can be brought here and even to America in this manner from the Mediterranean. Ingenious precautions are taken to see that rough weather does not affect storage conditions. In the old days one of the popular methods of artificial lowering of temperature was that of the direct expansion cold air machine. The air from the cargo spaces was sucked into the machine, compressed, cooled, expanded and sent back through the cargo spaces. This system proved, however, unsatisfactory, and has virtually been scrapped. The problem of the elimination of loss from fruit cargoes begins not in the cold store but in the orchard. A layman might expect different varieties of apples to vary in their carrying quantities. But experience has shown that apples of the same kind, even when grown near together and showing no difference if eaten as soon as plucked, vary considerably in their keeping power according to the soil on which they are grown. Thus Victoria plums under standard uniform conditions of commercial storage have had a life varying from one to six weeks. In another case Allington Pippin apples of the 1925 crop, taken from two different trees growing in the same garden less than 15 yards apart, showed a commercial storage life in the same cold store until January, 1926, in one instance, and in the other until May, 1926. Evidently growers, shippers and all concerned in the fruit trade dare not allow such results to be possible, for waste has to be paid for, and if the damage is charged to the public the consumption of fruit is liable to be lowered. It may be feasible to vary keeping quality by modifying soils, and this aspect of the matter, which is, of course, extremely complicated, is being strenuously tackled. If the tasks before scientific investigators are hard, the prizes are valuable. For, apart from the desirability of adding to knowledge, huge commercial interests are at stake. Our capacity for consuming fruit imported from the Southern Hemisphere is only beginning to be tested. It is scarcely too much to say that until after the war we had been accustomed to enjoy apples and oranges only in the colder months. The supplies now on the market all through the summer come wholly from the Southern Hemisphere. South Africa only started exporting oranges in the first decade of the present century, and then only in very small quantities. Now she sends nearly a million cases every season, and it is estimated that this figure could be multiplied tenfold in the next fifteen years if the demand were sufficient. It is such considerations that have led the Empire Marketing Board to give a substantial grant to the Low Temperature Research Institute at Cambridge, which is enabling the Institute to build a new and enlarged station, and considerably to extend its activities in all directions. But producers and consumers are alike dependent on workers in the spheres of low temperature research and soil investigation. These scientific inquirers have much ground to cover before we can claim completely to have learnt the art of carrying perishable cargoes half round the world.The New Statesman.
British Food Journal – Emerald Publishing
Published: Sep 1, 1927
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