APPLE RESEARCH

Otago Daily Times, Issue 22101, 3 November 1933, Page 4

APPLE RESEARCH

SHIP’S HOLD IN LABORATORY. i (From Our Own Correspondent.) LONDON, September 21. Newspaper, representatives and others were invited last week to inspect the laboratory of the Department of Scientific and Industrial Research at East Mailing, near Maidstone. The visitors were received by Dr C. West, the superintendent, a:.d were shown round by Dr A. J. M. Smith, of the Low Temperature Research Station at Cambridge, who is in charge of the experiments. , Dr Smith stated .that many of the difficulties of cold-storing foodstuffs and of carrying them overseas in refrigerated ships arose from the fact that foods were either living things, such as fruit, or the product of living things, such as meat, and cheese. Foodstuffs required for their preservation a very precisely controlled environment; on the other hand, they generated heat, and so upset arrangements for controlling the temperature; they consumed oxygen, and poisoned the atmosphere. The difficulties increased in proportion to the size of the stack of material being cold-stored. Ships’ holds were the largest and most closely packed of all cold stores. In order to study the subject adequately it had been necessary to construct a replica of a ship’s hold at the laboratory. The party saw the operations of grading, weighing, and packing apples, and afterwards inspected the experimental ship’s hold. This, inside the insulated walk, measures 34J x 301 x 15ft, has a capacity of nearly 16,000 cubic feet, and can take a "cargo” of approximately 130 tons (7000 bushel boxes) of apples, when fully loaded. It can be refrigerated either by means of brine pipes inside the hold (through which cold brine is circulated), or by circulating the air, by means of fans, over an external cooler and back again through the cargo. On a ship, these are known respectively as the “ grid ’’ system and the “ battery ” system of refrigeration. _ Each is capable of a number of modifications which can be experimented with in turn in the experimental hold. One of the fundamental criteria of success in a system of carriage is the ability to maintain a uniform temperature right through the cargo stack. Since the fruit generates heat it will tend to warm locally wherever the supply of cold air is inadequate. Some 200 thermometers are used in the experimental hold, to explore these temperature variations; they are buried in amongst the cargo, and read from a distance by an electrical mechanism. The readings are logged , from “ watch ” to "■watch,” and a "map” of the temperatures is made showing the conditions at each point of the stack. CIRCULATION OF AIR.

The experimental hold has it own environment (its own -“sea,” So to speak) in the form of an air-jacket, whose temperature can be fixed at any value. The conditions studied may be those of a ship in the tropics or in the cold North Atlantic;* -

i “Dunnage” is a very important practical problem. Air-spaces must be left between the boxes of fruit to allow the cold air to penetrate into the stack from the cooling pipes. These spaces are usually kept open by small lathes or battens (dunnage) between the individual boxes. Study of the problem has suggested that a-few large channels would be considerably more efficient than a great numebr of small crevices.

At the moment the hold is being loaded with its cargo of apples for the coming season’s experiments. The apples are received from neighbouring orchards as soon as picked, and are graded and packed at the laboratory. This work occupies a fortnight of more. The special type of case characteristic of cargoes from Australia is being employed this year—a matter of some importance, since the shape of the case, particularly, the presence or absence of a “bulge,” is probably a factor affecting the distribution of cold air amongst the stagk, and hence the uniformity of temperature. ,