234 III. DIGESTIBILITY OF FATS 



vate any deleterious effects. Evidence that the effect of polymerization 

 on digestibility is a general one which applies equally to animal and to 

 vegetable fats has recently been advanced by Roy. 108 The progressive 

 nature of the effect of heating is manifest from the data cited in Table 17. 



Table 17 



Effect of Thermal Treatment on Physical Constants and Coefficients of 



Digestibility of Ghees, Lard, and Hydrogenated Peanut Oil" 



Temperature (°C.) to which fat was subjected 



Substance Control 200 250 275 300 



Cow ghee 



Sapon. value 220 220 218 220 216 



Iodine value 35 35 33 31 .5 28.6 



Reichert value 20 20 18.6 17.3 16.4 



Coeff. of digestibility 98 97 . 6 97 93 89 



Buffalo ghee 



Sapon. value 227 226 225.8 226 222 



Iodine value 29.5 26.8 26.6 24.2 21.5 



Reichert value 26 26.2 24.6 22.7 21.6 



Coeff. of digestibility 95 95 94.6 90.2 87.6 



Lard 



Sapon. value 196 195.3 192 194 192.6 



Iodine value 60 61.5 60.8 59.6 56.8 



Coeff. of digestibility 97 97 96 . 4 92 90 . 4 



Hydrogenated peanut oil 



*Sapon. value 191.5 190 190.6 189.6 187.5 



Iodine value 66.8 66.8 66.0 65.3 62.6 



Coeff. of digestibility 97 97 95.2 93.0 88.2 



° Adapted from A. Roy, Ann. Biochem. Exptl. Med. (India), 4, 71-72 (1944). 



On the other hand, one must realize that a higher level of heat than 

 that to which food fats ordinarily are subjected must be applied to bring 

 about polymerization. No decreased growth rate of rats or decreased 

 efficiency in utilization of the diet could be demonstrated when diets 

 containing margarine fat at a 40% level were given, irrespective of whether 

 unheated fat was used or fat heated at 205°C. for eight hours (during which 

 successive batches of potato chips were fried). 109 Moreover, potato chips 

 fried in this fat possessed no inhibitory effects on rat growth. 



108 A. Roy, Ann. Biochem. Exptl. Med., 4, 71-72 (1944). 



109 H. J. Deuel, Jr., S. M. Greenberg, C. E. Calbert, R. Baker, and H. R. Fisher, Food 

 Research, 16, 258-280 (1951). 



