upon the market. The old-time product of Liebig's extract belongs to the second class, in which we also find many of our best known brands. The liquid extracts are varied and numerous and their number is rapidly increasing. The amount of meat extractives in some of these liquid products is remarkably small, the quantity of solids in two or three cases being under 10 percent. Alcohol is sometimes met with in these liquid preparations. The meat powders are far less numerous than the extracts of the first two classes. They consist largely, if not entirely, of albuminoses and peptones in addition to some insoluble proteid matter.
Moreover, it is necessary to distinguish between a meat extract containing large amounts of stimulating amido-acids and relatively small percentages of albuminoses, peptones and insoluble proteid matter on the one hand, and, on the other hand, an extract, or, more properly, a meat product, which consists largely of albuminoses, peptones and insoluble matter and relatively small amounts of amido-acids. The food value of this last group of products is undoubtedly greater than that of the former group, but being sold as meat extracts, their value should be based on the amount of extractives they contain and not on their food value.
The value of the amido-bodies, such as the meat bases, as food, is of uncertain character, but we must admit, as in the case of alcohol, they can at least be burned and furnish energy to the body. Like alcohol, the value of meat extractives lies principally in their stimulating qualities. The active principles of tea and coffee are on a similar basis. As these simpler amido-bodies are the final links in the long chain of hydrolytic products of the proteid molecule prior to the complete resolution of that molecule into carbon dioxid, water, etc., it is readily seen that an ounce of meat extractives (the various amido-bodies) represents a far larger amount of beef than an ounce of albuminoses does. The various protein bodies and amido-acids are closely interwoven and it is impossible to produce amido-acids without producing albuminoses and peptones. Consequently, every commercial meat extract must consist partly of albuminoses, peptones, etc. The best of our extracts on the market to-day contain about 50 percent of their total nitrogen in the form of meat base nitrogen. When an extract contains less than 5 percent of its nitrogen in the form of meat base nitrogen the term "extract" seems to be no longer applicable. It is evident that the product represents much less meat than an extract with 50 percent of its nitrogen in the form of meat base nitrogen, provided the total nitrogen in both cases is approximately equal.
The proteid matter coagulated by heating to boiling, as well as the proteid matter insoluble in cold water, are both undesirable factors in an extract of meat. As a rule, the lower the proportion of these constituents, the higher the character of the meat extract. The same thing holds true in regard to the presence of albuminoses and peptones.
