

DAIRY PRODUCTS. 23 



Tidy and Wiguer 1 have investigated the action of mammary tissue 

 on fats used as butter substitutes. 



By digesting a pure animal fat with the chopped-up tissues of the 

 udders of cows the authors found a marked chemical change produced. 

 Oleomargarine or tallow when treated in this way give rise to both 

 soluble and volatile fatty acids. Since both milk and butter contain a 

 certain amount of mammary tissue, in the form of casts from the mam- 

 mary glands, it is believed that they also would exert an influence on 

 animal fats. Butter appears to act more vigorously than milk in this 

 way, probably because it contains a larger percentage of mammary 

 tissue. 



NUTRITIVE VALUES OF BUTTER AND OLEOMARGARINES. 



On this subject Atwater 2 has collected valuable information, he says: 



The value of butter, as of any other food material for nourishment, depends upon 

 the amounts of its nutritive ingredients, their digestibility, and their uses in the nu* 

 trition of the body. 



CHEMICAL COMPOSITION. 



The food values of real and imitation butter, as compared with each other and 

 with other food materials, can bo best shown by first comparing their composition, 



It appears that the nutrients of the leaner kinds of meat and fish consist mostly 

 of protein, that the fatter moats and fish contain considerable fat with the pro- 

 tein, that the vegetable foods have for the most part very little fat, and abound 

 especially in carbohydrates, while the nutriments of butter and oleomargarine con- 

 sist almost exclusively of fats. Indeed, the protein and carbohydrates in both must 

 bo regarded as impurities. The quantities of fat are shown by analysis to be very 

 nearly the same in both. 



DIGESTIBILITY. 



Regarding the relative digestibility of butter and oleomargarine the experimental 

 facts at hand are meager. They imply, as would be expected from the composition, that 

 there is very little difference between the two. The study of the question is rendered 

 difficult by the fact that what is ordinarily called the digestibility of a food includes 

 several different things, the case with which it is digested, the time required for di- 

 gesting it, and the proportions of its several constituents that are digested. 



As to the comparative ease and time of digestion of butter and oleomargarine 

 nothing is definitely known, though there is little ground for assuming that, in the 

 alimentary canal of a healthy person, at any rate, one would bo digested and taken 

 into the circulation much more readily than the other. The actual amounts digested 

 are capable of more nearly accurate experimental estimate. During the past few 

 years very many experiments have been made, in Germany especially, to test the 

 quantities of the more important constituents of different foods digested by domestic 

 animals, and a considerable number have been carried out with men and children. 



The only comparative experiments on the digestibility of butter and oleomargarine 

 that have been reported are two series conducted by Professor Mayer, a German 

 chemist. One series was with a full-grown . man and the other with a boy of nine 

 years of age, both strong, healthy persons. The outcome was that both the man aud 

 the boy digested from 97.7 to 98.4 per cent, of the fat of the butter, and from 96.1 to 

 96.3 per cent, of the fat of the oleomargarine. The average difference was about 1.6 

 per cent, in favor of the butter. There are, however, certain unavoidable sources of 



1 Analyst, 1883, pp. 113 el, seq. 2 Bradstreet's, Saturday, June 19, 1886. 



