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Food Values and Adulterations: Place

Benzoic and Salicylic Acid. To detect sodium benzoate or benzoic acid and salicylic acid, macerate and filter a sample as above. By gently squeezing the bag or cloth containing the sample, obtain two ounces of the liquid. Place this solution in a bottle holding about five The ordinary quinine bottle of the druggist is convenient. Add a quarter of a teaspoonful of cream of tartar and about three tablespoonfuls of chloroform, and mix thoroughly with a splinter. Do not shake too vigorously or the chloroform will not separate readily from the rest of the liquid. Pour the mixture into a tumbler, and after the chloroform layer has settled to the bottom of the tumbler, take out with a medicinedropper all the clear chloroform possible and divide it into two parts, A and B.

Place one-half of the chloroform solution (A) in a glass sauce-dish.

Set the dish on the outside of a window-ledge close to the window, and allow the chloroform to evaporate.

In cold weather the sauce-dish should be placed in a pan of hot water before being placed on the windowledge. When the chloroform has evaporated, if the quantity of benzoic acid is sufficient it will be seen in the bottom of the dish in small flat crystals. If the dish is warmed slightly the odor of gum benzoin may be recognized. A better confirmatory test, however, is, without warming the residue left after the evaporation of the chloroform, to add to it a half teaspoonful of strong ammonia water and three teaspoonfuls of strong hydrogen peroxide, as obtained at the drug store, and let the solution stand over night. The next day pour the liquid remaining in the sauce-dish into one of the tall bottles used above, add a piece of turmeric-paper and then hydrochloric acid, drop by drop, stirring with a splinter, until the turmeric-paper changes from a brown to a clear yellow color, then add chloroform as in the first part of the test, and after stirring thoroughly take out the chloroform with the dropper and allow it to evaporate on the windowledge. Finally treat the residue remaining in the sauce-dish for salicylic acid as noted below. The treatment with ammonia and hydrogen peroxide was for the purpose of changing the benzoic acid to salicylic acid.

To test the other half of the solution (B) for salicylic acid, pour it into a tall five-ounce bottle containing a tablespoonful of water, and add to the solution a piece of iron alum about as large as the head of a pin.

Shake the mixture and allow the chloroform to again settle to the bottom of the bottle. If salicylic acid is present, the upper layer of the liquid, or the line separating the two liquids, will be of purple color.

Sulphites. To detect sulphites in food, as for instance in jelly or in sirups, place about an ounce of the material, with the addition of some water-if necessary to make a thin liquid, in a tumbler, add a dozen small pieces of zinc, and about fifty drops of hydrochloric acid. Cover the tumbler with a sauce-dish, and allow to stand for a few minutes in a warm place. In the presence of sulphites the gas, hydrogen sulphide, which has a disagreeable odor like rotten eggs, can be recognized in the tumbler by the sense of smell.

If the hydrogen sulphide cannot be detected by its odor, it can often be found by proceeding as follows:

Stick, by means of sealing wax, a clean, bright ten-cent piece on a splinter of wood so that it will hold the silver coin above the liquid in the cup. Place the stick and coin in the tumbler and let it stand covered in a warm place for from thirty minutes to an hour or so, if the color does not appear before. If the coin is stained brown to black, sulphites are indicated; the greater the quantity, the darker the stain. Saccharin. - Saccharin is used in the place of sugar to sweeten various food products. It is made from coal-tar and is about 500 times as sweet as ordinary sugar. To detect this substance, the sample of food is extracted with chloroform as described in the method for detecting sodium benzoate, and the chloroform solution is allowed to evaporate in a glass dish in the open air. If a considerable amount of saccharin is present the residue left in the dish will have an intensely sweet taste.

CANNED FRUIT AND PRESERVES There is very little excuse for the use of preservatives, and not any at all for the use of artificial coloring matters in canned fruits. The preservatives mentioned under canned vegetables are those more commonly used, and the methods for their detection given in the previous section may also be applied to canned fruits.

Jams, Jellies and Preserves.