830 XIII. ESSENTIAL FATTY ACIDS 



firmed by bioassay. Thomasson^^ reported a value of only 6.9% for lard 

 when tested by the latter procedure. Andrews and Richardson-^^ reported 

 an average linoleic content varying between 13.7 and 9.5% (average 11.6%) 

 for twenty -seven different samples of eighteen different brands of lard. 

 However, such analyses do not take account of the fact that arachidonic 

 acid is present in lard, and that this has a somewhat higher biopotency than 

 does linoleic acid. 



In contradistinction to the relative high content of EFA in chicken and 

 hog fat, the storage fat of beef cattle and of sheep represents only a mini- 

 mum level of EFA. Although ox depot fat has been reported to have 5.3% 

 of linoleate and 0.5% of arachidonate, Thomasson,!*^ employing a bioassay 

 procedure, obtained a figure of only 1.5% for beef suet. Sheep depot fat 

 has been reported to have 5% of linoleate, but this has not been confirmed 

 by bioassay. More precise data, confirmed by bioassay, are needed in the 

 case of animal fats. 



d. Presence in Hydrogenated. Fats. When fats are completely hydro- 

 genated, as, for example, coconut oil, they obviously lose all their EFA. 

 On the other hand, in the case of the vegetable fats which have been 

 partially hydrogenated for the preparation of margarines and shortenings, 

 appreciable quantities of the EFA may remain. One assay, which is 

 based upon a new chemical "isolation" method of Simmons and Quacken- 

 bush,*° assigned a value of 20.5% for the linoleate content of a common 

 shortening (Primex). On the other hand, Deuel and associates''^ recorded 

 values of 4.2% to 5.9% for the EFA content of different samples of a hydro- 

 genated vegetable margarine, whereas the value for a shortening prepared 

 by selective hydrogenation was 2.7% and that for one prepared by non- 

 selective hydrogenation was 13.2%. 



For a summary of the relative amounts of essential acids in hydrogenated 

 fats and in butters, see Table 3. 



It seems probable that the newer types of margarine, recently introduced 

 on the American market, which are composed of one fraction of oil hydro- 

 genated to a higher melting point than that of the former margarines, and 

 a second fraction only lightly hydrogenated, may be expected to have a 

 higher EFA content than those reported in Table 3. According to inves- 

 tigations carried on in the author's laboratory, new types of margarine 

 contained 6.9 to 8.4 % of essential fatty acids. Andrews and Richardson^^^ 

 reported variations in the linoleic acid content of various types of margarine. 

 They studied the linoleic acid content of fifty-seven samples of various 

 types of margarine obtained from different localities. The linoleic acid 



