Starch, which constitutes fifty-five per cent. of the corn kernel, can be converted into a variety of products for dietary and industrial uses. As found in corn, potatoes or any other vegetables starch consists of small, round, white, hard grains, tasteless, and insoluble in cold water. But hot water converts it into a soluble, sticky form which may serve for starching clothes or making cornstarch pudding. Carrying the process further with the aid of a little acid or other catalyst it takes up water and goes over into a sugar, dextrose, commonly called "glucose." Expressed in chemical shorthand this reaction is
C6H10O5 + H2O → C6H12O6
starch water dextrose
This reaction is carried out on forty million bushels of corn a year in the United States. The "starch milk," that is, the starch grains washed out from the disintegrated corn kernel by water, is digested in large pressure tanks under fifty pounds of steam with a few tenths of one per cent. of hydrochloric acid until the required degree of conversion is reached. Then the remaining acid is neutralized by caustic soda, and thereby converted into common salt, which in this small amount does not interfere but rather enhances the taste. The product is the commercial glucose or corn syrup, which may if desired be evaporated to a white powder. It is a mixture of three derivatives of starch in about this proportion:
| Maltose | 45 per cent. |
| Dextrose | 20 per cent. |
| Dextrin | 35 per cent. |
There are also present three- or four-tenths of one per cent. salt and as much of the corn protein and a variable amount of water. It will be noticed that the glucose (dextrose), which gives name to the whole, is the least of the three ingredients.
Maltose, or malt sugar, has the same composition as cane sugar (C12H22O11), but is not nearly so sweet. Dextrin, or starch paste, is not sweet at all. Dextrose or glucose is otherwise known; as grape sugar, for it is commonly found in grapes and other ripe fruits. It forms half of honey and it is one of the two products into which cane sugar splits up when we take it into the mouth. It is not so sweet as cane sugar and cannot be so readily crystallized, which, however, is not altogether a disadvantage.
The process of changing starch into dextrose that takes place in the great steam kettles of the glucose factory is essentially the same as that which takes place in the ripening of fruit and in the digestion of starch. A large part of our nutriment, therefore, consists of glucose either eaten as such in ripe fruits or produced in the mouth or stomach by the decomposition of the starch of unripe fruit, vegetables and cereals. Glucose may be regarded as a predigested food. In spite of this well-known fact we still sometimes read "poor food" articles in which glucose is denounced as a dangerous adulterant and even classed as a poison.
The other ingredients of commercial glucose, the maltose and dextrin, have of course the same food value as the dextrose, since they are made over into dextrose in the process of digestion. Whether the glucose syrup is fit to eat depends, like anything else, on how it is made. If, as was formerly sometimes the case, sulfuric acid was used to effect the conversion of the starch or sulfurous acid to bleach the glucose and these acids were not altogether eliminated, the product might be unwholesome or worse. Some years ago in England there was a mysterious epidemic of arsenical poisoning among beer drinkers. On tracing it back it was found that the beer had been made from glucose which had been made from sulfuric acid which had been made from sulfur which had been made from a batch of iron pyrites which contained a little arsenic. The replacement of sulfuric acid by hydrochloric has done away with that danger and the glucose now produced is pure.
The old recipe for home-made candy called for the addition of a little vinegar to the sugar syrup to prevent "graining." The purpose of the acid was of course to invert part of the cane sugar to glucose so as to keep it from crystallizing out again. The professional candy-maker now uses the corn glucose for that purpose, so if we accuse him of "adulteration" on that ground we must levy the same accusation against our grandmothers. The introduction of glucose into candy manufacture has not injured but greatly increased the sale of sugar for the same purpose. This is not an uncommon effect of scientific progress, for as we have observed, the introduction of synthetic perfumes has stimulated the production of odoriferous flowers and the price of butter has gone up with the introduction of margarin. So, too, there are more weavers employed and they get higher wages than in the days when they smashed up the first weaving machines, and the same is true of printers and typesetting machines. The popular animosity displayed toward any new achievement of applied science is never justified, for it benefits not only the world as a whole but usually even those interests with which it seems at first to conflict.
The chemist is an economizer. It is his special business to hunt up waste products and make them useful. He was, for instance, worried over the waste of the cores and skins and scraps that were being thrown away when apples were put up. Apple pulp contains pectin, which is what makes jelly jell, and berries and fruits that are short of it will refuse to "jell." But using these for their flavor he adds apple pulp for pectin and glucose for smoothness and sugar for sweetness and, if necessary, synthetic dyes for color, he is able to put on the market a variety of jellies, jams and marmalades at very low price. The same principle applies here as in the case of all compounded food products. If they are made in cleanly fashion, contain no harmful ingredients and are truthfully labeled there is no reason for objecting to them. But if the manufacturer goes so far as to put strawberry seeds—or hayseed—into his artificial "strawberry jam" I think that might properly be called adulteration, for it is imitating the imperfections of nature, and man ought to be too proud to do that.