Otto Hehner

“ Very few organic materials undergo decomposition, as it were, of their own accord. They may lose water by evaporation, and fatty substances may alter by the absorption of oxygen from the air. They are otherwise quite stable and unchangeable while not attacked and eaten up by living organisms, or while the life with which they may be endowed is in a state of suspense. An apple is alive and in breathing undergoes its ripening change; a grain of wheat is dormant and does not alter. A substance, in order to be a food material, must be decomposable under the attack of a living organism ”

“ In its crudest forms as old as commerce itself, it has progressed with the growth of knowledge and of science, and is, in its most modern developments, almost a branch—and that not the least vigorous one—of applied science. From the mere concealment of a piece of metal or a stone in a loaf of bread or in a lump of butter, a bullet in a musk bag or in a piece of opium, it has developed into the use of aniline dyes, of antiseptic chemicals, of synthetic sweetening agents in foods, the manufacture of butter from cocoa-nuts, of lard from cotton-seed and of pepper from olive stones. ”

“ All decomposition of food is due to the development within the food of living organisms. Under conditions under which living organisms cannot enter or cannot develop food keeps undecomposed for an indefinite length of time. The problem of food preservation resolves itself, therefore, into that of keeping out or killing off all living things that might feed upon and thus alter the food, and as these organisms mainly belong to the family of moulds, yeasts and bacteria, modern food preservation is strictly a subject for the bacteriologist. ”

“ The crops sometimes take up arsenic to a slight extent, but happily the plant is more selective than man, and no serious amount of poison absorption appears to be possible. The risk of contamination is, of course, much greater with substances which, like glucose, are not further purified by crystallization, but retain whatever impurity is introduced into them. Glucose is not only used in beer, in which by legal enactments it is permitted to be used, but is also substituted for sugar in a number of food products, and is liable to carry into them its contamination. ”

“ All preparation of food for the table, cooking being the most important, tends towards preservation, but is effectual only for a few hours or days at most, unless special means are adopted to prevent reinfection. The housewife covering the jam with a thin paper soaked in brandy, or the potted meat with a thin layer of lard, attempts unconsciously to bar the road to bacteria and other minute organisms. ”

“ Milk.—Milk adulteration means in modern times either addition of water, abstraction of cream, or both, or addition of chemical preservative. The old stories of the use of chalk or of sheep’s brains are fables. Owing to the wide variation to which milk is naturally subjected in composition, it is exceedingly difficult to establish beyond doubt whether any given sample is in the state in which it came from the cow or has been impoverished. The composition of cow’s milk varies with many conditions. ”

“ The organisms may come from the air, the soil or from animal sources. The air teems with organisms which settle and may develop when brought upon a favourable nidus; the organic matter of the soil largely consists of fungoid life; while the intestinal canal and other mucous membranes of all animals harbour bacteria, sarcinae and other organisms in countless millions. Whenever, therefore, food material is exposed to the air, or touched by the soil or by animals or man, it becomes infected with living cells, which by their development lead to its decomposition and destruction. ”

“ In reality even wider limits of variation must be reckoned with, because small farmers sell the milk of single cows, and this, as shown above, may fluctuate enormously. The Board of Agriculture, in pursuance of the powers conferred upon it by the Food Act 1899, issued in 1901 “The Sale of Milk Regulations,” which provide that where a sample of milk (not being milk sold as skimmed or separated or condensed milk) contains less than 3% of milk-fat, or less than 8·5% of non-fatty solids, it shall be presumed, until the contrary is proved, that the milk is not genuine. ”

“ Destruction of life takes place more rapidly in solutions showing an acid than a feebly alkaline reaction; hence acid fruit is more easily preserved than milk, which, when quite fresh, is alkaline. By cooking, therefore, food becomes temporarily sterile, until a fresh crop of organisms finds access from the air. By repeated cooking all food can be indefinitely preserved. One of the most important functions of cookery is sterilization. ”

“ While for all common forms of fraud the common law is in most cases considered strong enough, special laws against the adulteration of food have been found necessary in all civilized countries. A vigorous branch of chemical literature deals with it; there exist scientific societies specially devoted to its study; laboratories are maintained by governments with staffs of highly trained chemists for its detection; and yet it not only develops and flourishes, but becomes more general, if less virulent and dangerous to health. ”

“ It may at first sight appear strange that the person who robs milk of its most valuable portion, the cream, may prepare a legitimate article of food from the remainder, while he who to that remainder adds something to replace the fat does an illegitimate act, but it must be taken into consideration that the replacement is frequently made with fraudulent intent and that the ordinary purchaser cannot by taste or smell distinguish the adulterated from the genuine article, while there is no difficulty in recognizing skim-milk cheese. ”

“ Imperfect sterilization shows itself in many cases by gas development within the tin, which causes the ends to become convex and drummy. More frequently than not the contents of the larger tins, containing meat or other animal products, are not absolutely sterile, but the conditions are mostly such that the organisms which have survived the cooking process cannot develop. When they can develop without formation of gas dangerous products of decomposition may be produced without showing themselves to taste or smell. ”

“ As the limits embodied in the milk regulations were necessarily fixed at figures lower than those which are usually afforded by genuine milk, and as it is a comparatively simple matter to ascertain the percentage of fatty and non-fatty solids, a strong tendency exists to bring down commercial milk to the low limits of the regulations without coming into collision with the law. The fat of milk is its most valuable and most important constituent. The exact determination of the percentage of fat is therefore the chief problem of the milk-analyst. ”

“ The use of sugar as a preservative depends upon the fact that, although in a dilute solution it is highly prone to fermentation and other decomposition, it possesses bactericidal properties when in the form of a concentrated syrup. A sugar solution containing 30% of water or less does not undergo any biological change; in the presence of organic acids, like those contained in fruit, growth of organisms is inhibited when the percentage of water is somewhat greater. ”

“ To preserve food in a permanent manner and on a commercial scale it has to be cooked in a receptacle which must be sufficiently strong for transport, cheap, light and unattacked by the material in contact with it. None of the receptacles at present in use quite fulfils the whole of these conditions: glass and china are heavy and fragile, and their carriage is expensive; tinned iron, so-called tin-plate, is rarely quite unaffected by food materials, but owing to its strength, tenacity and cheapness, it is used on an ever-increasing scale. ”

“ For each oil the iodine absorption is a fairly constant quantity; this number, together with the determination of the amount of caustic alkali needed for complete saponification, the thermal rise with strong sulphuric acid or with bromine, the refraction of light and the specific gravity, now enable the analyst to form a fair idea of the nature of any sample under examination, and, in consequence of this advance in knowledge, adulteration of oils has much declined. The most common adulterant of the more valuable oils, like olive oil, is cotton-seed oil. ”

“ In animals suffering from tuberculosis and other bacterial affections the milk may be infected within the udder. Milk as it reaches the consumer rarely contains less than 50,000 bacteria and often many millions per cubic centimetre. In fresh country cream 100 millions per cubic centimetre are not unusual. These bacteria are of many kinds, some of them spore-bearing. The spores are more difficult to kill than the adult organism. The first step towards preservation is the removal of the dirt unavoidably present, to the particles of which a considerable proportion of the bacteria adhere. ”

“ Oils.—For very many years all oils were considered to be composed of olein, that is to say, the triglyceride of oleic acid, with small quantities of impurities; chemists, therefore, to distinguish oils of various origin, confined themselves to tests for these impurities, employing so-called colour reactions based upon the change of colour of the oil by various reagents such as sulphuric, nitric or phosphoric acids. These reactions were exceedingly indefinite and unsatisfactory and oil adulteration was prevalent and almost undiscoverable. ”

“ Nature preserves the germs in seeds and nuts, which are laden with otherwise decomposable food material, by the simple expedient of water removal. The life of cereal grains and many seeds appears to be unlimited. By the removal of water the most perishable materials, like meat or eggs, can be rendered unchangeable, except so far as the inevitable oxidation of the fatty substances contained in them is concerned and which is independent of life-action. ”

“ There is an altogether different class of butter adulteration which concerns itself with the substitution of other fatty matters for the whole or part of the really valuable portion of the butter-fat. Margarine is the legalized and therefore legitimate butter-surrogate, prepared by churning any suitable fat with milk into a cream, solidifying the latter by injection into cold water and working the lumps together, precisely as is done in the case of the churned cream of milk. ”

“ With the separation of country from town, the development of manufacturing nation as distinct from agricultural and food-producing people, the spreading of civilized man from torrid to arctic zones, the needs of travellers on land and sea and of armies on the march, the problem of the prevention of the natural decomposition to which nearly all food substances are liable became increasingly urgent, and forms to-day, next to the production of food, the most important problem in connexion with the feeding and the trade of nations. ”