4(34 Philippine Journal of Science i«t 



may continue indefinitely. The rate of this process depends upon the 

 amount of surface exposed to the air, compared with the total volume 

 of oil, and may in extreme cases cause an exceedingly rapid deterioration. 

 It may be entirely prevented by storing the oil in completely filled recep- 

 tacles, impervious to air. 



Along with the two above-mentioned processes, a slight hydrolysis due 

 to heat, moisture and free acids already present is constantly taking place. 

 It may be reduced considerably by filtration, which removes most of the 

 water, together with the organic impurities. 



There is reason to believe that some hydrolysis is brought about by 

 enzymes produced by the molds, as unheated oils which have been filtered and 

 rendered antiseptic increase in acidity somewhat more rapidly than do 

 heated ones under the same condtions. However, this distinction is not 

 so apparent after the first year. 



Light has apparently no effect on the oxidation by air of coconut oil. 



The third and latest paper 5 from the Bureau of Science 

 laboratory on the storage of coconut oil deals chiefly with methods 

 of measuring rancidity. On the subject of the cause of ran- 

 cidity the authors, besides quoting from Walker and others, 

 make the following observation : ,; 



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. 



Regarding the nature of rancidity they state: 7 



If the formation of rancidity is caused or accompanied by an oxidation, 

 one of the first changes to take place would be the breaking down of the 

 unsaturated acids into simpler acids * * *. 



On the same subject Lewkowitsch 8 comes to the following 

 conclusion : 



I therefore define as rancid those oils and fats, the free fatty acids 

 of which have been acted on by the oxygen of the air, in the presence 

 of light. Similar explanations have been given before and the only new 

 element I can claim here would consist in ascribing more emphatically 

 than has been done hitherto the initial phase of rancidity, namely, the 

 hydrolysis, to the accelerating action of enzymes. 



The view that light is a necessary condition for rancidity, 

 which Lewkowitsch insists upon, and which he apparently bor- 



5 Brill, H. C, and Parker, H. 0., The rancidity of Philippine coconut oil, 

 Philip. Journ. Sci. § A 12 (1917) 95-110. 



6 Op. cit. 96. 



1 Op. cit. 108. 



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

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



A more recent text, Edible Oils and Fats, by C. A. Mitchell, London, 

 Longmans, Green & Co. (1918), presents no new data on this subject. 



