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Food Values and Adulterations: Spices
Spices and Condiments. - Spices, especially those which are ground, are very often adulterated. If a sample has not a strong spicy odor and taste, this is an indication of as adulteration. Cocoanut shells, prune pits and inert materials are often used as adulterants, but starchy substances are also extensively used. But observe that many spices also naturally contain starch. This is not the case, however, with cloves, mustard, and cayenne. Hence these may be tested for starch as follows:
Stir a half-teaspoonful of the spice into half a cup of boiling water, and heat in a pan of water on the stove for a few minutes. Cool the mixture, and dilute with water SO that the solution shall not be very strongly colored. Add a few drops of tincture of iodine. The production of a blue color indicates starch.
To test for turmeric-a vegetable coloring matter in ground mustarddigest some of the sample with alcohol, and after a short time dip a piece of white filter-paper in the mixture. If the paper is colored a bright yellow turmeric is probably present.
BAKING CHEMICALS Baking Powder. - As the statement that appears on the label of a baking powder can is often deceptive, it may be of interest to prove whether a sample contains alum or not. To test for alum, make a fresh extract of logwood, either from the chips or the solid extract, by treating with water and pouring away the first and second extracts. Use the third extract obtained and allow it to settle. Place two teaspoonfuls of baking powder in a teacup and add to it four teaspoonfuls of cold water. With a medicine-dropper add twenty drops of extract of logwood to the mixture and stir with a splinter. Place the teacup in a pan of hot water on the stove and examine the color after two hours. If the baking powder contains alum, or a compound of aluminum, a distinct lavender color will be produced, but if this substance is not present in the sample, only a dirty brown or FOOD VALUES AND ADULTERATIONS pink color will appear. It is well to make a test at first on samples of known composition, so as to recognize the colors accurately. Cream of Tartar. - The cream of tartar on the market is frequently adulterated with acid calcium phosphate, alum, and even plaster, and starch. A simple test to determine the purity of the sample is to stir one level teaspoonful of it into a cupful of boiling water. Pure cream of tartar will dissolve completely, but many of the adulterants will only partially dissolve. The solution may then be poured into a tumbler that has been previously warmed.
When cold, the cream of tartar will crystallize out in very characteristic crystals. To detect starch, add to a little of the cooled solution a few drops of tincture of iodine. The production of a blue color indicates that starch or flour is present.
TEA AND COFFEE There is hardly any adulterated tea on the market, although there are some very poor grades and there may be too much "tea siftings" in the sample. Ground coffee is very often adulterated. Some simple tests for adulterants may be made. If ground coffee is dropped into a glass of cold water, the genuine coffee will float, and will not discolor the water for several minutes. Most of the adulterants sink to the bottom and leave a brown trail in the water. But little coffee is contained in the socalled "coffee substitutes." The proportion of coffee in a sample may be ascertained approximately by dropping it into cold water, as very few coffee substitutes will float.
Many of the substitutes are of a starchy nature. Starch may be tested for in the ordinary infusion prepared for the table, when cold, by diluting it until it is not too strongly colored, and then testing by tincture of iodine. (See test under "Sugar.") DAIRY PRODUCTS Milk, butter, ice cream and cheese are frequently adulterated.
Milk is adulterated by adding water, coloring matters and preservatives.
When water is added to milk, it changes the natural color, and the milk becomes bluish-white. If a yellow coal-tar dye has been added to the milk to restore the natural color when watered, this may be detected by adding an equal quantity of strong hydrochloric acid to a sample of the milk and afterwards heating.
A pink coloration indicates the presence of the dye. Another test is to allow the milk to stand in a tumbler for about twelve hours, or until the cream rises, and notice the color of the cream and of the milk layer. If the lower layer is of a yellow color, about the same as that of the cream, an artificial color is indicated.
To detect annatto, a yellow coloring matter, stir some washing soda into the milk, and after standing a few minutes filter through filter paper. Then wash the milk off the paper, and if annatto is present the paper is colored yellow to orange.
If the milk does not turn sour in the usual time, the presence of a preservative is indicated. Baking soda is sometimes added to correct the acid of the milk. If an appreciable quantity of this substance has been used, the milk, after standing a few hours, will have a slightly alkaline reaction; that is, it will change a piece of yellow turmeric paper to an orange-red color.
Formaldehyde. - Other preservatives are sometimes used, but that which is the most common is formaldehyde or formalin, because a little goes a long way as a preservative.
To detect this substance, place four tablespoonfuls of the sample in a teacup, with an equal quantity of strong hydrochloric acid and a piece of ferric alum about the size of the head of a pin. After mixing, by giving the contents of the cup a rotary motion, place the cup in a pan of boiling water on the stove, and allow to stand for five minutes. If formaldehyde is present, the mixture will be of a purple color. A similar test may be made for formaldehyde in ice cream, although if starch is present in the cream this may modify the shade of the purple.
Butter. The substitutes for genuine butter are "process" or "renovated" butter, and oleomargarin or "butterine." Process butter is made by treating old or rancid butter by melting, skimming and allowing the brine and curd to sink to the bottom, whence it is drawn off. Air is then blown through the melted butter-fat, and the product is churned with milk or cream. Oleomargarin is made from various mixtures of oleo-oil, cottonseed-oil, neutral lard and milk or butter. It should always be sold under its true name.
The spoon test may be used to distinguish fresh butter from renovated butter and oleomargarin. A lump of butter the size of a hickory nut is placed on a large iron spoon and heated over the flame of a small kerosene or alcohol lamp or over a gas flame. Fresh butter will melt quietly, with many small bubbles throughout the mass, which produce much foam; oleomargarin or process butter will splutter and crackle, like hot fat containing water, and produce but little foam.
To make the "milk test", as it is called, place about two ounces of sweet milk in a wide-mouthed bottle, which is set in a pan of boiling water on the stove. When the milk is hot, add a teaspoonful of butter, and stir with a splinter until the fat is melted. Place the bottle in a pan of ice water and stir continually while the fat is solidifying. If the sample is butter, either fresh renovated, it will solidify in a granular condition and be distributed through the milk in small granular particles. If, on the other hand, the sample is oleomargarin, it solidifies or practically in a single lump, so that it may be lifted from the bottle with a stirrer.
Eggs. Probably the best method for testing the freshness of eggs is the time-honored one of candling.
The egg is held between the eye and a bright light. A fresh egg shows a perfectly uniform rose-colored tint, while if not fresh there will be numerous dark spots. In packed eggs there is a tendency for the white and yolk to slightly intermingle along the line of contact. Packed eggs also are apt to adhere to the shell on one side. If eggs have been in a nest for any length of time they are smooth and glossy and the appearance is entirely different from the dull, rough surface of fresh eggs.
MEAT PRODUCTS The preservatives most commonly used in meat products are borax, boric acid and sodium sulphite. The latter chemical also develops a bright red color in the meat in imitation of the natural red of fresh cut meat.
If the meat keeps an exceptionally long time without a tendency to spoil, or if it retains its red color, the presence of preservatives may be suspected.