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Food Values and Adulterations: Extract
FLAVORING EXTRACTS AND CON- DIMENTS Lemon Extract. - The extracts in most common use are those of lemon and vanilla. Extract of lemon, according to the United States Pharmacopœia, should contain 5 per cent of oil of lemon. About 85 per cent of alcohol is required to keep this in solution. Much of the extract of lemon on the market contains SO little oil of lemon that it can with difficulty be measured. The oil is also often replaced by some other essential oil, as that of lemon grass.
To hold the small quantity of oil of lemon in solution, a 25 or 30 per cent alcohol is often used. The yellow color of this product is produced by the use of a yellow anilin dye. As oil of lemon is held in solution by alcohol, to test the character of the extract, add to a teaspoonful of the sample, in a tumbler, three times as much water. If the liquid does not become milky the sample is not genuine. If the solution remains perfectly clear on the addition of the water, or is slightly turbid only, the extract is of very poor quality. When buying lemon extract, shake vigorously. If the foam does not disappear immediately the extract is not genuine.
Vanilla Extract. - Extract of vanilla, if genuine, is made by exhausting vanilla beans with alcohol. Frequently Tonka beans are in part or wholly substituted for the vanilla beans. The coloring matter in the artificial extract is usually caramel, burnt sugar, or prune juice, and artificial vanillin is added to strengthen the ordinary product. To detect caramel, shake the bottle containing the extract, and observe the foam on the top of the liquid. If the extract is pure the foam is colorless and persists; but if caramel has been added, there is a brownish color at the point of contact of the bubbles until the last bubble disappears.
As pure extract of vanilla contains considerable resin, which is held in solution by the alcohol, a test may be made for this as follows: Evaporate about two tablespoonfuls of the extract in a sauce-dish placed over a teakettle of boiling water.
When one-third of the liquid has evaporated off, pour the residue into a tumbler and dilute with water to the original volume. If the liquid is turbid, and the resin separates as a brownish substance, the extract is probably genuine. If, on the other hand, the liquid remains clear after dilution, though of course of a brown color, this indicates that it is artificial.