Rancidity

“ Since moisture, air, light and enzymes, produced by the presence of organic impurities, are necessary for the rancidity of a fat or oil, the methods of preventing rancidity are given. Complete dryness, complete purification of fats and oils and storage without access of air or light are desirable. Simple as these means may seem, they can only be approximated in practice. The most difficult problem is the removal of the last trace of moisture. Impurities may be lessened very often by the use of greater care. ”

“ But many of the free fatty acids of fish oils readily oxidize on exposure to air and light, developing during the process a darker color and an unpleasant odor and taste which we call rancidity. Once fats have become rancid they can never be restored to their original sweetness.
What conditions promote rancidity? First, the fat must be decomposed or "split" into glycerin and free fatty acid. Next it must oxidize. Just as fish contain autolytic enzymes that decompose protein, so they also contain fat-splitting enzymes. These enzymes require moisture and warmth for their activities. ”

“ It has been shown by Dr Griesler that nitric ether, and its alcoholic solution, act in the same manner. A few drops are not only sufficient to prevent rancidity, but, it is said, will even destroy the disagreeable odour of rancid fat. When heated to remove the alcohol, they immediately become bright, clear, and scentless. See Oil, Glycerin, Olein, Palmitin, Stearin, Tallow, &c., also below. ”

“ Both red oil and stearic acid being fatty acids, readily unite with the alkali carbonates, carbon dioxide being formed in the reaction and this method is extensively used in the formation of soap from them.
RANCIDITY OF OILS AND FATS.
Rancidity in neutral oils and fats is one of the problems the soap manufacturer has to contend with. The mere saying that an oil is rancid is no indication of its being high in free acid. The two terms rancidity and acidity are usually allied. Formerly, the acidity of a fat was looked upon as the direct measure of its rancidity. ”

“ The unsaponifiable matter naturally present as cholesterol, or phytosterol, ranges in the various oils and fats from 0.2 to 2.0 per cent. All oils and fats contain more or less free acidity; but excess of acidity, though it may be due to the decomposition of the glyceride, and does not always denote rancidity, is undesirable in soap-making material. Rancidity of fats and oils is entirely due to oxidation, in addition to free acid, aldehydes and ketones being formed, and it has been proposed to estimate rancidity by determining the amount of these latter produced. ”

“ The splitting of fats into glycerin and the particular acid or acids involved may be brought about by bacteria. An illustration is the development of rancidity in butter at times and the “strong” odor of animal fats on long keeping and of many kinds of cheese—“limburger”—in this country. Generally speaking, however, fats are not vigorously attacked, as is illustrated by the difficulties due to accumulation of fats in certain types of sewage-disposal works. ”

“ Besides these mechanical impurities, fats, especially if old, sometimes contain small amounts of free fatty acids which suffice to impart to them the objectionable odor and taste peculiar to every rancid fat. While some fats, such as bear’s grease, butter of cacao, oil of sesame, and some others, remain free from rancidity for a long time, others undergo this change very rapidly; in fact, we may say that every fat which shows the slightest odor should be called rancid, for pure fat is absolutely odorless. ”

“ The largest number of high-grade oils contain less than three percent of free fatty acid, but a larger quantity, as has been stated, does not render the oil inedible unless actual fermentation has taken place producing rancidity. Rancidity appears to be the result of the generation of other acids than oleic, and also aldehyds, formic, butyric, acetic, and œnanthylic acids have been found. Olive oil is a typical non-drying oil and therefore shows a less rise in temperature when mixed with sulfuric acid than other vegetable oils. ”

“ Fats and the fat oils are best preserved by being run into glazed jars, and secluded from the action of the air. A little benzoic acid or gum-benzoin, dissolved in them by heat, will generally prevent, and in all cases greatly defer, the accession of rancidity. We introduced this method into the laboratory in our early days of manipulation, and ourselves, and others to whom we have made it known, have since employed it with undeviating advantage in the manufacture of cerates, ointments, and other preparations containing fatty matter or the fixed oils. ”

“ Fortunately we know two substances which materially counteract the tendency of fats to become rancid: salicylic acid and benzoin. Either of these substances is added to many perfumery articles, especially pomades, in order to prevent rancidity; an admixture of from one-one-thousandth to five-one-thousandths parts of solid salicylic acid suffices, according to our experiments, for the purpose; of benzoin we need about three-fourths of an ounce for every quart of fat; the resin is only partly soluble in fat, but imparts to it its vanilla-like odor. ”

“ Monosaturated fats also have far less tendency to go rancid than any other type. Vegetable oils with high proportions of unsaturated fats, the kind that all the authorities push because they contain no cholesterol, go rancid rapidly upon very brief exposure to air. The danger here is that rancidity in vegetable oil is virtually unnoticeable. Rancid animal fat on the other hand, smells "off." Eating rancid oil is a sure-fire way to accelerate aging, invite degenerative conditions in general, and enhance the likelihood of cancer. ”

“ The excess of food is not properly acted upon by the digestive juices, and is liable to undergo fermentation, and thus to become a source of irritation to the stomach and the intestines. If too much and too rich food be persistently indulged in, the complexion is apt to become muddy, the skin, especially of the face, pale and sallow, and more or less covered with blotches and pimples; the breath has an unpleasant odor, and the general appearance of the body is unwholesome. ”

“ To those who vomit bile, a cataplasm must be applied, made of dates, the rind of pomegranate, and gall, boiled in wine or oxycrate, along with pounded bread. And acacia, hypocystis, and the flowers of the wild pomegranate and sumach, ought to be added to the cataplasm. A cupping-instrument also, when applied with a strong heat, is of great service. Food ought to be given frequently in small quantities. To those who vomit black bile and have the stomach inflated, apply sponges soaked in hot vinegar of the most acrid qualities, or a cataplasm of the leaves of the ivy boiled in wine. ”

“ See Fermentation, Malt-liquors, Wines, &c.
Gas′tric Acidity. Acidity of the stomach; a common and well-known symptom of weak or disordered digestion.
Treat., &c. Small doses of absorbents or antacids, three or four times daily, to which some tonic bitter, as calumba, cascarilla, chamomile, gentian, or orange-peel, may be added. Stomachic stimulants, as capsicum, ginger, mustard, or wine, &c., taken with, or after, meals, are also useful. The diet should be light and nutritious; and acescent vegetables,32 over-ripe fruit, and weak new beer or other liquors avoided as much as possible. ”

“ Cardialgia. Heartburn originates from the inactivity of the stomach, whence the aliment, instead of being subdued by digestion, and converted into chyle, runs into fermentation, producing acetous acid. Sometimes the gastric juice itself becomes so acid as to give pain to the upper orifice of the stomach; these acid contents of the stomach, on falling on a marble hearth, have been seen to produce an effervescence on it. ”

“ It floats on the stomach in the form of an oily pellicle, becoming odorous, and sometimes highly rancid, and in this state excites heartburn, disagreeable nausea, eructations, and sometimes vomiting. It appears to me, that the greater tendency which some oily substances have than others to disturb the stomach, depends on the greater facility with which they evolve volatile, fatty acids, which are for the most part exceedingly acrid and irritating. The distressing feelings excited in many dyspeptics by mutton fat, butter, and fish oils, are, in this way, readily accounted for. ”

“ That we may understand the Reason of the Hydrophobia, it is to be Remarked, that this dread of Water does not come on till the latter end of the Disease, Three or Four Days before Death; that is, not till this preternatural Fermentation in the Blood is come to its Heigth; and as in the Dog, so in the Patient, a great quantity of Fermentative Particles is thrown off upon the Glands of the Mouth and Stomach, as appears by his Foaming at the Mouth, &c. ”

“ Disease is a fermentation and decay-process of body-substance or of surplus and unnatural food-material, which in course of time has accumulated, especially in the digestive organs, and which makes its appearance in the shape of mucus-excretion.
That is, it means in the last instance nothing but the chemical decomposition, the decay of cellular albumen. As is well known, this process is accompanied by stench, while nature combines the originating of new life with fragrance (the building of plants.) Properly man in perfect health should exhale fragrance, particularly so with his hair. ”

“ The cause of this is that my products are only prepared for carrageen size, inasmuch as my investigations have shown that it is the best, the cheapest and the most adapted for all varieties of edges.
The homogeneousness of the tragacanth mucilage in cold solution comes naturally after the size is five or six days old, because within this time fermentation of lactic acid occurs, which opens the cells of the small granules of starch while at the [48] same time boiling heat has an immediate result in the same direction. ”

“ This cause is fermenting food and the products of this fermentation, viz.: alcoholic yeast and alcohol, vinegar yeast and acetic acid, carbonic acid gas, embolism, and interference with nutrition. Consumption of the bowels can be produced at any time in the human subject in from fifteen to thirty days, and consumption of the lungs inside of ninety days, by special, exclusive, and continued82 feeding upon the diet that produces them—that is, food containing starch and sugar in alcoholic and acetic acid fermentation.’” Dr. ”

“ Food passing from the stomach, thus supercharged with Superacidity a primary cause acid, causes irritation of the mucous lining of the alimentary tract. This results in nervousness, insomnia, intestinal congestion (constipation) , fermentation, and intestinal gas, while the excess of acid in the stomach causes irritation of the mucous surface of that much-abused organ, which develops first into catarrh, then ulceration, and sometimes into cancer. The accumulation of gas from the fermenting mass in the intestines causes irregular heart action, and sometimes heart failure. ”

“ In many cases the change of food must be strictly observed and persevered in for a long time before a cure can be effected. In some instances where the powers of the stomach were too weak to prevent the food from undergoing perhaps both a vinous and acetous fermentation, and where, in consequence of the disengagement of gas and the formation of acid, the most excruciating pains were felt, the most dreadful sickness experienced, and all the symptoms of indigestion present in the most aggravated state ”

“ Superacidity may appear immediately after eating, and the symptoms such as a lump in the stomach, or a sour fluid rising in the throat may also appear within an hour after meals, but fermentation, which produces the same symptoms, does not manifest itself until the acid has acted upon the food, which requires from two to four hours, governed by the time required to digest the different articles of which the meal is composed. ”

“ Most vegetables retain their tartness, which, by vellicating the nerves, occasions pains and convulsions; acid eructations arise, the cardia suffers pain, the throat is parched, and the teeth blunted. On the contrary, both flesh and eggs rot, and fat aliments grow rank: hence proceed putrid eructations, immoderate thirst, and continual fluxes; digestion is always difficult, troublesome, and malignant; the aliments cease to afford [63] nourishment, nor do they any longer repair, but irritate and weaken. ”

“ However, where putrid bile is to be corrected and discharged, by stool, very good purposes may, perhaps, be answered by taking the Magnesia, joined with a sufficient quantity of acid to neutralize it, while in a state of effervescence; or by swallowing the Magnesia and the acid, one immediately after the other, so as to produce the fermentation in the stomach: for thus the fixed [Pg 37] air with which the Magnesia so greatly abounds, being let loose, may powerfully correct the tendency to putridity in the contents of the primæ viæ, and at the same time evacuate them downwards. ”

“ In this connection may be mentioned the fact that, when bran « 186 » drenches are used, in which lactic acid is developed, the butyric fermentation is liable, in hot weather, to take its place, and as butyric acid is a powerful solvent of gelatinous tissue, and the dissolved tissue itself feeds the fermentation, rapid destruction of the skins is the result. Cleanliness, scalding out of the drench vats, and washing the bran before using with cold water to remove adhering flour, are useful precautions. ”

“ Fevered stomach is caused by fermentation of food—hyperacidity. After the diet is balanced so as to be chemically harmonious, the next most important thing is copious water-drinking at meals and between meals. ”

“ Washed with an aqueous solution (four drachms of acid to a gallon of water) , or kept in it, or wrapped in cloths soaked in this water, keeps fresh for a very long time. Butter already rancid can be improved by treatment with a stronger solution (8 drachms of acid to 1 gallon of water) , followed by washing in pure water. The bad smell often arising in salted butter is entirely prevented by addition of the acid. ”