THE RANCIDITY OF PHILIPPINE COCONUT OIL 1 



By Harvey C. Brill and Harrison 0. Parker 



(From the Laboratory of Organic Chemistry, Bureau of Science, Manila) 



The cause, measurement, and prevention of rancidity in oils 

 have engaged the attention of many investigators. 



Walker - decided that the rancidity of coconut oil arose from 

 the action of heat, light, moisture, and air on the oils. He 

 believes that most of the changes in the oil take place in copra 

 due to the activity of the microorganisms and offers as a possi- 

 ble explanation of the cause of rancidity in pure oils "that a 

 small percentage of fatty acid is oxidized to an oxyacid, which 

 in turn forms a lactone, and (assuming the formation of hydro- 

 gen peroxide) the latter would give rise to a peracid, which, in 

 turn, would oxidize the free glycerine to an aldehyde." Walker 

 states that an oil which has been rancid and later refined again 

 becomes rancid more readily than an oil that has never shown 

 rancidity. No explanation for this greater tendency to rancid- 

 ity is offered by him. 



As an estimation of the rancidity of coconut oil he determined 

 the free fatty acids and made the fuchsin-sulphurous acid test 

 for aldehydes and the peroxide test. He disclaims placing any 

 credence on the free fatty acid determination as a measurement 

 of the degree of rancidity of oils and asserts that the ordinary 

 aldehydes are not offensively odorous. Therefore it appears 

 from his results that 'the rancidity of oils must be due to 

 the presence of compounds other than aldehydes or free fatty 

 acids. Yet he maintains, "The most satisfactory [test for 

 rancidity], in my experience, is that with fuchsin-sulphurous 

 acids, shaking up about equal parts of oil and reagent." 



Haller and Lassieur 3 take issue with many other investigators 

 regarding the cause of rancidity when they state that the un- 

 pleasant odor of commercial coconut oil is due to the presence 

 of free fatty acids, such as caproic, caprylic, capric, and lauric. 

 In the volatile products from the refining of coconut oil these 

 authors 4 found ketones. 



1 Received for publication March, 1917. 



2 Walker, H. S., This Journal (1906), 1, 1917. 



'Haller, A., and Lassieur, A., Compt. rend. Acad. sci. (1910), 150, 1013. 

 4 Ibid. (1910), 151, 699. 



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