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Food Values and Adulterations: Starch

There is no class or food products, with the exception of spices, so commonly adulterated as jams and jellies. The basis for the cheap jellies is often the pomace or refuse from the cider-mill, the sweetening is glucose or corn sirup, the coloring matter is a coal-tar dye. Hence the use of a preservative is almost always necessary. Starch is often used as a filler or gelatinizing agent.

Dyeing Test.-To detect a coal-tar or anilin dye, mix a few teaspoonfuls of the jam or jelly with some water and filter first through cloth and afterwards through filter-paper. The filter-paper should be folded across the middle, and again at a right angle to this fold. Place in the funnel so that there shall be three thicknesses on one side and one on the other.

Moisten the paper with water to hold it in place. Add a few drops of hydrochloric acid to the filtered solution of the jelly, and place it in a teacup in a pan of boiling water on the stove. Boil a small piece (about an inch square) of white woolen cloth or nun's veiling with a little soap, and, after rinsing, place it in the colored solution to be tested.

After heating for ten minutes, take out the cloth and rinse in clear water.

If the cloth is not colored, the experiment may be discontinued. If, however, the cloth is colored, to confirm the test, heat the cloth in a teacup in clear water containing about a teaspoonful of ammonia.

This will dissolve the anilin color out of the cloth, but will have little effect on a natural fruit color. Take the piece of cloth and add enough hydrochloric acid to the contents of the cup so that the solution will not smell of ammonia. Put into this solution a new piece of washed woolen cloth and heat again in a pan of water. If an anilin dye is present, the cloth will be dyed, and after heating a short time, may be taken out and rinsed in clear water. This method of testing may also be applied to tomato catsup, which is frequently artificially colored. starch Starch. - If considerable paste has been added to a jelly, it may be detected by adding to the cold filtered solution a few drops of FOOD VALUES AND ADULTERATIONS tincture of iodin. The production of an intense blue color indicates starch.

Observe that this color may be modified by any dye that is present in the sample examined.