96 The Philippine Journal of Science im 



Lewkowitsch 5 asserts— 



I therefore ascribe the primary cause of rancidity, namely the formation 

 of free fatty acids, to the action of moisture in the presence of soluble 

 ferments, which act as catalysts or accelerators ; * * * Rancidity is not 

 due, as is still widely believed, to the presence of free fatty acids alone; in 

 other words, rancidity must not be considered as coterminous with acidity 

 * * * It is only when oxygen and light gain access to the acid fats that 

 the conditions favoring the setting in of rancidity are provided. Rancidity 

 is rather due to the direct oxidation of free fatty acids by the oxygen of 

 the air, assisted and intensified by the exposure to light. 



The presence of free fatty acids can be, therefore, considered 

 only the first step in the formation of rancidity. 



Batter placed in storage for prolonged periods of time often 

 acquires a rancid odor. This rancidity has been ascribed to 

 the activity of microorganisms by various authorities. The 

 latest of these investigators is Dyer," who has shown by a thor- 

 ough study of cold-storage butter that the change in flavor is 

 due to the slow oxidation of the nonfatty portions of the butter. 



We believe that the nonfatty material in coconut oil has a 

 profound influence on its character, and experiments are now 

 in progress to test this out. 



Schmid 7 classifies oils as "sour fats," "rancid fats," and 

 "sour and rancid fats." In coconut oils we have distinct classes 

 of odors existing in the rancid oils, namely, sour odor, pos- 

 sessed especially by some oils made by Filipinos from fresh 

 nuts which are characterized by a high acid value ; 8 esterlike " 

 and smokelike odors, observed particularly in oils made from 

 moldy copra which has been prepared by the tapahan (Filipino 

 grill for drying copra meat) method; and a third with an odor 

 of stale lard, which is shown by sweet coconut oil that has be- 

 come rancid due to exposure to the air. The investigation now 

 under way will attempt to determine the difference in the chem- 

 ical character of the various odors and whether the cause of 

 each particular odor is peculiar to it. 



The present article deals with the various methods of meas- 



* Lewkowitsch, J., Chemical Technology and Analysis of Oils, Fats and 

 Waxes. Macmillan & Co., London (1913), 1, 52. 



'Journ. Agr. Research (1916), 6, 927. 



1 Schmid, A., Zeitsckr. f. anal. Chem. (1910), 37, 301. 



8 For method of preparation see Parker, H. 0., and Brill, H. C, This 

 Journal, Sec. A (1917), 12, 



Coconut meat which has been acted upon by bacteria possesses an 

 esterlike odor, and this odor in coconut oil probably arises from the action 

 of the bacteria on the meat before pressing. 



