DIGESTIBILITY OF SOME ANIMAL FATS. 3 



the temperature of boiling water, to drive off surplus water and thus 

 improve its keeping qualities. Care was exercised not to heat the fat 

 too high. 1 Judged by the usual household tests, the resulting product 

 in all cases was most satisfactory, being of good color and flavor and 

 free from sediment. 



As sufficiently large quantities of the fats to be studied could not 

 be consumed in the natural state, a method of preparing them for 

 eating was sought. The most satisfactory one found was to incor- 

 porate the fat in a blanc mange or cornstarch pudding. This was 

 best prepared by cooking skim milk, to which sugar and a consider- 

 able quantity of a caramel solution had been added, in an ordinary 

 double boiler, at as high a temperature as could be reached (nearly 

 100° C). A mixture of commercial cornstarch and the fat under 

 consideration was then slowly added with continuous stirring, and 

 the heating continued until the starch was well cooked. Skim milk 

 was used to avoid the presence of any considerable amount of butter 

 fat, which would interfere with the study of the particular fat under 

 consideration. The caramel solution was designed to mask the pres- 

 ence of the large quantity of fat by supplying a characteristic and uni- 

 form color and flavor to the blanc mange, for a distinctly fatty flavor is 

 disagreeable to many persons and, furthermore, experience has shown 

 that it is highly desirable in making experiments of this character to 

 avoid as far as possible any psychic effects, which in some instances 

 may play an important role in the digestion of food. It was usually 

 necessary to add such a large quantity of the caramel solution that 

 the blanc mange had a slightly bitter taste, but this feature was 

 readily overcome by the addition after cooling of a little vanilla extract. 

 The blanc mange prepared in this way resembled a common household 

 dessert, except that it was not noticeably sweet. It has been used 

 to a considerable extent and with good results in this laboratory as a 

 medium for supplying special foodstuffs in experimental diets. The 

 question of the nature of the food was not discussed with the subjects 

 and the masking of the fat was so complete that none of them appeared 

 at any time to notice differences in the flavor of the blanc mange ; at 

 least no comments on the matter were made. 



In studying the digestibility of a single food, experience has shown 

 that it is desirable to incorporate it in a very simple mixed diet, since 

 the ordinary individual is so accustomed to a mixed diet that, no 

 matter how palatable a single food may be at first, it eventually 

 becomes distasteful. Consequently, in these experiments it was 

 decided to use, in addition to the blanc mange containing the fat under 

 consideration, a very simple mixed basal diet composed of a commer- 

 ( dal wheat biscuit, fruit, and tea or coffee, with a little sugar if the 

 subject desired. 



1 H has been noted in the Biochcmlc Laboratory of the Bureau of Animal Industry that the keeping 

 qualities of fats which have been subjected to elevated temperatures have apparently been lessened. 



