The Minor Horrors of War

by Sir A. E. Shipley

Fig. 12.—Ephestia kühniella. A, Larva; B, pupa. Greatly magnified.

First, as to infestation. The biscuit must become infested either (1) at home before packing, (2) during transit, or (3) in the country where they are stored. The biscuits are packed in tins, hermetically sealed, and enclosed in wooden cases to prevent injury; it was therefore obvious that if insects could be found within intact tins it would be demonstrated at once that infestment must have taken place in the factories, and not subsequently.

Fig. 13.—Corcyra cephalonica. Moth-infested biscuit.

With a view to determine the origin of infestation sample tins were withdrawn from stocks at various stations abroad, and inspected by experts at Woolwich; and tins which, after careful examination, had been pronounced intact, were found to contain Ephestia kühniella and Corcyra cephalonica in various stages of development, thus proving conclusively that infestation had taken place in the factories before the tins were soldered, and indicating that preventive or remedial measures must be undertaken within the biscuit-making factories themselves.

It is obvious either that the heat to which the biscuit is subjected in the process of baking is insufficient to destroy any of the insect eggs present in the moist dough or that the moths and beetles deposit their eggs in or on the biscuits after baking, and during the process of cooling and of packing into the tins. Cooling before packing is necessary in order to allow the moisture in the centre of the biscuit to become evenly distributed throughout the ‘tissue’ of the biscuit. And it is during the time occupied in cooling and packing that the biscuit is exposed to the greatest risk of infestation; any risk occasioned by subsequent injury must be exceptional, and is probably negligible.

By a series of most ingenious experiments, the two investigators were able to determine the temperature in the centre of the biscuits during the various stages of its baking and cooling. Army biscuits are made from dough which contains about 25 per cent. of water. When stamped out they are placed in rows on the revolving floor of an oven, and are submitted to a high temperature for twenty minutes whilst they travel over a space of 40 feet. The dough at first contains, as we have said above, 25 per cent. of water, but during baking this is reduced to about 10 per cent., and the moisture now collects in the centre of the mass of the biscuit in consequence of the external hardening or ‘caramelisation,’ as it is called. The holes which are pricked in so many biscuits of course help to equalise the spread of the moisture throughout the biscuit.

Too little attention has been paid to the internal temperature of edibles which are being cooked. Very few people, for instance, have any conception of what is going on in the centre of a joint of meat whilst it is being roasted or boiled. After two hours’ boiling the temperature in the centre of a large ham has only risen to 35° C.; after six hours’ boiling to 65° C., and it is only after ten hours’ continuous boiling that 85° C. is reached. I have, I am sorry to say, no conception as to how long a ham ought to be boiled, but it is obvious that to be really effective against such parasites as Trichinella—the causa causans of trichinosis—the cooking of pork and ham should be more prolonged and thorough than seems to be customary. But that is another story.

However, to return to our biscuits. The Colonel and Mr. Durrant devised an ingenious instrument which determined the rising temperature at the centre of our Army biscuits whilst baking. When the tip of their recording apparatus lay within the moist area of the biscuit, the temperature registered was only a little over 100° C.; but when the tip of the instrument rested on the hard ‘caramelised’ portion much higher temperatures were observed—even as high as 125° C. Colonel Beveridge and Mr. Durrant were thus able to establish the fact that the temperatures of the biscuit were, during baking, such as to rule out the idea that the eggs of the biscuit-moth—which do not survive a temperature of 69° C. for twelve minutes—were deposited in the biscuit before cooking.

After the baking is completed the biscuits are cooled, and it is at this period that they are most exposed to risk of infestation by Ephestia kühniella. This insect is a well-known nuisance in Flour-mills. So persistent and numerous are these moths at times that they clog the rollers with their cocoons, and sometimes completely stop them. The webbing of the elevators in the mills gets covered with them and with their silky skeins, and then the elevators stop working. They mat together the flour and meal with their silken excreta, and so uniform is the temperature of the Mill, and so favourable to the life of the insect, that they complete their life-cycle in this country in two months, and in the warmer parts of America even more rapidly. In well-heated mills the proceeding is continuous, so that six generations at least may be produced each year.