DIGESTIBILITY OP SOME NUT OILS. 13 



The average coefficient of digestibility of the total fat of the diet 

 is 94.4 per cent. If proper allowance is made for the metabolic 

 products and the undigested fat remaining from the basal ration it 

 becomes 97.6 per cent for English-walnut oil alone. The protein and 

 carbohydrate of the diet are shown to be 69.6 per cent and 97.2 per 

 cent digested, respectively. 



The difference between the coefficient of digestibility, 97.6 per cent, 

 obtained in these experiments and the 85 per cent or less obtained by 

 Jaffa 1 in his series of 11 digestion experiments, in which the whole 

 nuts were eaten, is thought to be due in part to the form in which 

 the oil was used and may be due in part to Jaffa's considering the 

 ether extract of whole nuts as fat whereas substances other than fat 

 were doubtless extracted, and also may be due in part to no correc- 

 tion being made for metabolic products occurring in the ether ex- 

 tract of the feces. In the latter case it was taken as a constituent 

 of the nut and was probably less readily and completely acted upon 

 by the digestive juices than when it had been mechanically separated 

 and was taken as a separated fat. 



The subjects consumed on an average 78 grams (69.9 grams, 83.8 

 grams, 81.6 grams) of English-walnut oil daily. All three of the 

 subjects reported a laxative effect as a result of the diet ; one experi- 

 enced the effect at the beginning of the test period, one at the end, 

 and one during the entire experimental period. Accordingly, it is 

 believed that the limit of tolerance for this oil is not greatly in excess 



of 80 grams daily. 



HICKORY-NUT OIL. 



The oil of the hickory nut {Carya ovata) is not separated for 

 edible purposes in this country. It is not without interest to note, 

 however, that the American Indians used hickory-nut oil for food 

 purposes. The oil, according to Carr, 2 was obtained by mixing the 

 pounded nuts in boiling water, straining off the oily liquid, and 

 skimming off the oil which floated on the water in which the nuts 

 were boiled. " [They] kept it in gourds or earthen pots, etc., using 

 it as we do butter on their bread or to give body and flavor to their 

 broth when meat was scarce." 2 



Carr also states that oil was obtained from acorns and used in a 

 similar way. 



The digestibility of hickory-nut oil is of interest in view of the 

 large quantities of hickory nuts eaten yearly and especially since the 

 edible portion is reported 3 to contain 67 per cent of oil. 



1 Loc. cit. 



2 Proc. Amer. Antiquarian Soc, n. ser., 10 (1895), pp. 171, 172, 181. "The Food 

 of Certain American Indians and their Methods of Preparing It." 

 3 U. S. Dept. Agr., Office Expt. Stas. Bui. 28 (1906), rev. ed., p. 75. 





