20 OLIVE OIL AND ITS SUBSTITUTES. 



would not affect the solid fatty acids. Cotton-seed oil would in< -\ e 

 all of these figures. 



TABLK XIX. The Iodin mniion-* and tin- on- ant of solid full;/ <idx of ruriou* oils. 



The addition of mustard oil would increase the iodin numbers, but 

 decrease the solid fatty acids. Lard oil would decrease the Hiibl 

 number and increase the solid fatty acids, but would not affect the 

 iodin number of the liquid fatty acids. In many cases, however, 

 especially if but. small amounts were added to olive oil, the changes in 

 the factors would be so slight as to give no indication of any 

 adulteration. 



FREE FATTY ACIDS. 



The free fatty acids were determined by the method described in 

 the Provisional Methods for Food Analysis" and the results calculated 

 as oleic acid. One cubic centimeter of deci-normal alkali is equal to 

 0.0282 Tram of oleic acid. This determination is of considerable 



<^ 



value, in that it gives some idea of the condition of the oil. As a rule 

 thi> figure increases with age and may be to some extent an index of 

 the rancidity of the oil. The amount of free acid greatly att'ects the 

 .phy>ical constants of oils as has already been shown. All oils have 

 some free acid present, even when freshly pressed. Its amount prob- 

 ably depends on the condition of the fruit or seed and the . proce - 

 of manufacture. Milliau. Bertainchand. and Malet 7 ' found as high as 

 :i.'.i per cent of free acid in freshly pressed olive oil, probably due to 

 the overripe or decayed condition of the olives. 



With a number of cold-pressed seed oils manufactured in this 

 laboratory the determination of free fatty acids was made within three 

 day> after the oils were proved, with the following results: Sunflower 

 oils. n. is and l.T'J percent: peanut oil. <>.<M percent: mustard-seed 

 oil. l.i:-' per cent: and rape-seed oil. n.r,:i per cent. These figures 

 show the presence of considerable amounts of free acids in the seeds. 

 In Table XX are given the data showing the quantity of free acid in 



U. S. l>.pt. ALT.. r,mv:iu of ( 'hrmistrv Kill. >:>. j.. '27. 

 ''Rapport snr l-s hnilr- d'olivr ilr Timisir, HKX). 



