THE RANCIDITY OF PALM KERNEL 

 AND OTHER FEEDING CAKES 



By J. R. FURLONG, Ph.D. 



{Imperial Institute, London.) 



With the great increase in the use of pahii kernel cake, which has taken 

 place in this country in the last few years, attention has been drawn to 

 the rancidity which the cake is liable to develop under certain conditions. 

 R. B. Calder (see this Journal, April, 1916, vii, 470) has shown that the 

 cake develops rancidity under sterile conditions and concludes that the 

 action is due to the presence of a lipase. Calder has taken as his criteria 

 of rancidity a sour smell in some cases and an acid reaction with litmus 

 in others. There is some confusion in the use of the terms "rancidity" 

 and "acidity." Although rancidity stands in close relationship to acidity 

 and invariably accompanies a high acidity in oils and oil cakes, the terms 

 are not synonymous. Lewkowitsch {Oils, Fats and Waxes, i, p. 50 et seq.) 

 defines rancidity of an oil or fat as the production of a disagreeable smell 

 and acrid taste, due to the direct oxidation of the free fatty acids by the 

 simultaneous action of oxygen and light, and states that rancidity does 

 not appear until free fatty acids are produced. Considerable doubt exists 

 as to the nature of the oxidation products to which the rancid smell and 

 acrid taste are due, some observers attributing these properties to 

 aldehydes and ketones. In the absence of information as to the nature 

 of the changes which occasion rancidity there is no method of estimating 

 the extent to which rancidity has been produced in any particular case, 

 though the acidity is an indication of the initial phase of the change. 

 The degree of rancidity is influenced by the nature of the fatty acids 

 present, that is to say, the ease with which they form oxidation products, 

 and the odour and taste of the latter. 



In the experiments upon which this paper is founded, and which 

 have been carried out at the Imperial Institute, the amount of acidity 

 developed under certain conditions in palm kernels and in cake and meal 

 made from them, in comparison with other common feeding cakes, has 

 been determined, and the nature of the action investigated. The results 

 establish the presence of a fat-splitting enzyme or lipase in palm kernels 



