Generally speaking a “new” loaf is demanded and the baker who cannot deliver “new” loaves loses trade. But what is a “new” loaf? From the point of view of the chemist this question has formed the subject of innumerable investigations. A definition of a “new” loaf demands an understanding of “staleness” and the staling of bakery products is a subject of great complexity. The old idea was that it was entirely a question of the “drying out” of the bread, but cereal chemistry has proved that such a solution, namely the prevention of “drying out,” is only of partial efficacy; in fact “staleness” is caused by a change in the starch of the flour which is inherent in it and cannot be prevented by precautions which maintain the moisture content at a certain figure. The investigation of this type of staling has occupied the attention of many famous chemists, but the full explanation has not yet been obtained. Mass production has demanded many studies in that aspect of science known as “physical chemistry.” An example can be found in the preparation of certain sauces. Those of you who have made mayonnaise sauce know that to beat the olive oil into the mixture is fraught with difficulties. By means of the fork, used as a beater, the oil is distributed in very small particles through the mass of liquid, so that every globule of oil is separated from every other one. If the action docs not proceed properly the system breaks down and the mayonnaise “turns” and is spoiled. The manufacturer has to prevent this “turning,” not in a few pints but in hundreds of gallons. It is the chemist who has enabled him to do this and to manufacture with success those scores of salad‐dressings which are so delectable and the purchase of which relieves the housewife of so many hours of work and so much arm‐ache. An example of some interest is concerned with smoked salmon, which normally is a very variable product, whether it be the highly salted variety of the northern climes or the much less salted kind which has found favour in this country. The production of a lightly salted product is far more difficult than the more salted variety because much smaller changes in salt content become more noticeable. These small differences are so obvious to the confirmed smoked salmon eater that he detects not only the differences between one grade and another, but also the differences of salt content that occur in different parts of the same side of fish. It has fallen to the chemist so to change the methods of production of the lightly flavoured variety that the distribution of salt through the fish is even and the flavour therefore constant. This study of smoked salmon is only an example of the very big problem of standardisation, standardisation demanded by the consumer—and it follows that the big manufacturer must produce goods of standard flavour and appearance. Science steps in and gives the manufacturer those controls which enable him to produce, day in and day out, that standard range of article, whether it be ice‐cream or toad‐in‐the‐hole, Worcester sauce or cheese cakes, roast beef or jelly crystals. Modern science has introduced a new factor into our conception of what food should be. In the past it was only necessary to ensure that food should be “pure and wholesome,” by which was meant—in general terms—digestible and without any harmful constituents, be they natural or adventitious, bacterial or otherwise. So long as food complied with this broad definition everyone was satisfied. But biochemists and physiologists have demonstrated the importance of other factors, salts and vitamins, and it is necessary to consider the new situation thus created because it may be that the treatment of food to retain those substances may make it necessary to change preconceived notions. It may be that “palatability” may be affected, palatability which includes taste and appearance and odour. The whole subject is so complicated and, notwithstanding the enormous amount of work carried out, so little understood that no one as yet can be dogmatic, no one can state what are the optimum amounts of vitamins required by ordinary persons to keep them in good health. Having, however, decided the amount required, are we to try to preserve such quantities as occur naturally, or are we to fortify the food which we cat by added synthetic or even by purified natural vitamins? A further important consideration is whether the degree of maturity of, say, fruit in relation to maximum vitamin content coincides with optimum palatabilty. Certain it is that information gradually being accumulated on the importance—in many cases vital importance—of the minor constituents of foodstuffs leads to the conclusion that, to ensure the presence of all valuable minor constituents—be they known or unknown—the foodstuffs must, as articles of diet, be ingested almost in their entirety. This is probably an extreme view, for, in many cases, the result would be a product of reduced palatability or appearance, or, what is probably more important, “different,” and people do not like their food to be abnormal, i.e., to differ from their preconceived notion of what it should be. Nevertheless an “improvement” in the method of production, put into practice by the food manufacturer with the best intentions, may possibly result in a lowering of the dietetic value of the food, as, for example, by mechanical removal of an important part (the classical example being polished rice), by heat treatment, by oxidation or by materials added during cooking. The minor metallic constituents of food are gradually being revealed in their true importance. Copper, zinc, and iron are now known to be of importance. It is probable that every baby is born poor in calcium but rich in iron; milk, the natural food of the infant, is rich in calcium. It is only in the last few years that it has been shown that green vegetables as usually cooked are of very little real value. Cooking green vegetables in water containing sodium carbonate results in the almost complete destruction of the Vitamin C, and the discarding of the water removes the extracted salts. A green product certainly results but of greatly reduced nutritional value. On the other hand, it would appear that little destruction of vitamin activity takes place when the canning of vegetables or fruits is properly controlled. Sherman has said that attention to mineral salts and vitamins will lead to “buoyant” as distinguished from merely “passable” health. It is obvious that education of the public is essential if an intelligent use is to be made of the knowledge being gained by chemists and allied scientists. It is a most important fact that methods are being developed to assay foods for vitamins by chemical means. Biological feeding tests are obviously unsuitable for control purposes but, as the chemical identity of the vitamins becomes more clarified, chemical tests will become available for their determination. It is obviously the duty of the medical services of the country to guide the public as far as is possible on questions of nutrition. When such guidance becomes effective, the food producer will not be slow to see that his goods are up to the standard necessary, adding one more burden to the already loaded back of the chemist concerned with food production.
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