CHEMICAL PROPERTIES OF FATS AND OILS 287 



Table 40 

 Peroxide Values of Three Fats as Determined by Three Different Methods" 



" F. E. Volz and W. A. Gortner, J. Avi. Oil Chemists' Soc, 34, 417-420 (1047). 



reaction time to one hour, and by the addition of carbon dioxide to mini- 

 mize the further oxidation of the fat. 



The most widely used method is the so-called Swift stability test."*'^ 

 This involves the determination of the period of "induction" under certain 



HOURS 



Fig. IC. The variation in the length of time (in hours) and the induction period in 

 the absorption of oxygen for six commercial samples of lard.*^* 



standardized conditions of temperature and oxygen addition. The induc- 

 tion period lasts for varying periods of time with different oils. During this 

 interval, practically no oxygen is absorbed and no increase in the blank read- 

 ing for the peroxide value obtains; as soon as the induction period is com- 

 pleted, oxygen absorption takes place very rapidly and a sudden marked 



«' A. E. King, H. L. Roschen, and W. H. Irwin, Oil & Soap, 10, 105-109 (1933). 

 «« H. O. Triebold and C. H. Bailey, Cereal Chem., 9. 50-64 (1932V 



