14 



BULLETI^r 1033, U. S. DEPARTMENT OF AGEICULTUEE. 



The fats studied shoTved coefficients of digestibility ranging from 

 91.0 to 97.4 per cent, except in blended cottonseed fat melting at 

 50° C, wliicli gave a coefficient of digestibility of 57 per cent. It is 

 interesting to note that the blended fat "with the highest melting 

 point, namelj^, corn fat melting at 54° C, was 91.5 per cent di- 

 gested, while straight hydrogenated peanut fat with a melting point 

 of 52.4° C. was found to be only 79 per cent digested. 



A comparison between Table 10 and Table 11, adapted from the 

 report -' of earlier work with hydrogenated oils of the same origin 

 as those used in blended form, gives an idea of the relative effect of 

 the two methods of preparation upon cligestibilit3^ 



Table 11. 



-Suinmary of digestion experiments icith hydrogeimted vegetable oils 

 in a simple diet. 



Num- 

 ber of 



Kind of fat. 



Melting 



point of 



fat. 



lodin 

 number. 



Digestibility of entire ration. 



Digesti- 

 bility of 



expen- 

 ments 

 con- 

 ducted. 



Protein. 



Fat. 



Carbo- 

 hydrate. 



hydro- 

 genated 

 vegetable 

 oil alone. 



5 



Cottonseed 



35 



38.6 



46 



37 



39 



43 



50 



52.4 



33 



43 



50 



89.6 



Per cent. 

 69.2 

 69.5 

 71.7 

 69.1 

 74.0 

 73.8 

 68.6 

 55.9 

 72.0 

 76.3 

 69.6 



Per cent. 

 93.6 

 92.7 

 92.7 

 95.0 

 93.3 

 93.5 

 88.1 

 73.8 

 91.7 

 91.8 

 83.2 



Per cent. 

 96.9 

 97.3 

 97.6 

 96.9 

 97.6 

 96.8 

 97.6 

 97.2 

 97.4 

 97.0 

 97.3 



Per cent. 

 96.8 



1 



do 



95.5 



3 



do 



72.8 

 81.3 



94.9 



5 



Peanut 



98.1 



3 



do 



95.9 





do 



78.8 

 58.5 



96.5 



4 



do 



92.0 



3 



do 



79.0 



5 



Com 



89. 

 74.9 

 55.4 



94.7 



5 



do 



95.4 



5 



do 



88.5 









The blended fats seem to be, as a rule, slight!}^ better utilized than 

 the straight hydrogenated oils melting at the same temperature. 



While no definite data are available regarding the cause of higher 

 digestibility for blended fats, it is not without interest to suggest, 

 as was done in an earlier paper, that in the process of digestion 

 saponification may take place only on the exterior of the particles of 

 hardened fat (i. e., for those melting at temperatures considerably 

 above that of the human body), which decrease in size as the process 

 of digestion continues. If surface area be thus a factor, then the rate 

 of digestion and possibly the extent of digestion of a hydrogenated 

 fat having a high melting point is governed to some extent by the 

 size of the jDarticles of hydrogenated fat ingested. If this hypothesis 

 be tenable, it follows that particles of blended fat which are honey- 

 combed with veins of a low melting fat would, after they had come to 

 the temperature of the body, present greater surface area than par- 

 ticles of straight hj^drogenated oil, which present only an exterior 

 surface to the action of the digestive juices. 



*3Amer. Jour. Physiol., 54 (1921), No. 3,, pp. 479-488. 



