GELATINIZING AGENTS. 37 



preservation of this color is important, as the appearance of jellies and 

 jams undoubtedly influences their real value, especially in the sick 

 room, where they are used to a great extent, but the possibilities of 

 deception as to the quality and purity which the addition of coloring 

 matter afibrds entirely overbalance any argument in its favor. By the 

 judicious use of coal-tar colors apple jelly flavored with currants can 

 be given the appearance of the pure article, or a cheap fruit or a vege- 

 table pulp can be mixed into a jam: a jelly made of glucose and starch 

 may be served to consumers who demand pure goods. In most 

 European countries certain stated colors are allowed in food prod- 

 ucts which have no natural color but are ordinarily colored commer- 

 cially, such as candies, confections, liqueurs, and similar products, but 

 great care has l^een taken in the selection of these colors to exchule 

 any that ma}' be injurious, either from being toxic in themselves or 

 lia))le to contain injurious or poisonous impurities. Lists of the colors 

 allowed by difl'erent countries have been published,'' and from these 

 it would be possible to select harmless colors. The use in fruit prod- 

 ucts of colors of a vegetable origin is unquestionably nearly obsolete, 

 as. coal-tar colors are both cheaper and more duraVjle. The latter are 

 always liable to contain metallic impurities, such as zinc, copper, tin, 

 lead, and arsenic retained during the process of manufacture, and which, 

 when introduced into the food, even in the small quantities that are 

 used, are, to say the least, a source of danger. Others of the coal-tar 

 colors contain metallic atoms in their molecules — for example, mala- 

 chite green, which i^ a double chlorid of zinc combined with the organic 

 group. Even some of the vegetable colors are lakes of tin or some other 

 metal. These facts all go to show that manufacturers should use great 

 care in the selection of only the purest colors for use in food products. 



GELATIXIZING AGENTS. 



Many fruits do not readily form a good jelly, especially when a little 

 overripe, and it is necessary that some material be added in order to 

 give the product the proper consistency. There are several articles 

 that may be used to effect this result. Gelatin, agar, or some fruit 

 which has a high gelatinizing power may be added. It has been 

 claimed'' that gelatin is used, but in the large number of samples 

 examined there was no indication that such was the fact, (xelatin is a 

 very highly nitrogenized product, and even very small amounts would 

 raise the nitrogen content far above the normal. Agar is another 

 substance that might be used, and to much better advantage than 

 gelatin, because of its very high gehitinizing power (a 1 per cent solu- 

 tion forms a stiff' jelly) and because it is very similar in composition to 



•T. S. Dept. of Agr., Bureau of Chemistry Bui. 61, p. 9. 

 ^Rept. Dairy and Food Comniission, Minnesota, 19(X), }>. 102. 



