I 



IX. OCCURRENCE 545 



more than twice the concentration of nicotinic acid as the rest of the apple; 

 pear peehngs have three times the concentration of peeled pears. Similar 

 findings have been recorded for plums, sweet potatoes, tomatoes, and yams. 

 White potatoes seem to be an exception in that peelings and the peeled 

 potato have about the same nicotinic acid concentration.'* In inactive bean 

 seeds, the concentration of nicotinic acid was 40 7 per gram in the sprout, 

 28 7 per gram in the cotyledons, and 7 7 per gram in the cuticle. In the 

 whole bean, 96% of the nicotinic acid was in the cotyledon.^' 



Little information is available on the distribution of nicotinic acid within 

 cells. E. R. Isbell and associates^* studied the distribution of several vita- 

 mins between nuclei and the whole cell in beef heart and mouse mammary 

 carcinoma cells. In beef heart the nuclei had a concentration of nicotinic 

 acid nearly three times that of the entire cell. In mouse carcinoma the 

 reverse was true in that the entire cell had considerably higher nicotinic 

 acid concentration than the nuclei. On a weight basis, three-fourths of the 

 total cellular nicotinic acid was in the cytoplasm of these cancer cells. In 

 the hen's egg, the whites have seven times the concentration of the yolks 

 (on a dry-weight basis).* 



D. STABILITY IN FOOD 



Nicotinic acid is one of the most stable of the vitamins against the ordi- 

 nary conditions met in food processing, storage, and cooking. Some losses 

 in cooking are encountered, particularly where there is an opportunity for 

 leaching out. Nicotinic acid is quite stable in canning processes. In canned 

 foods stored 2 years and at storage temperatures up to 100°F., the losses 

 rarely exceed 15 %.*^"^° There is little or no loss with frozen storage or dry 

 storage. ^'"^* Usual methods of curing and cooking result in losses of 15 to 



'^ T. Terroine and J. Desveaux-Chabrol, Arch. set. physiol. 1, 117 (1947). 

 »3 E. R. Isbell, H. K. Mitchell, A. Taj'lor, and R. J. Williams, Studies on the Vitamin 

 Content of Tissues, Vol. II, Univ. Texas Publ. 4237, 81 (1942). 



34 L. E. Clifcorn Advances in Food Research, 1, 39-104 (1948). 



35 F. C. Lamb, A. Pressley, and T. Zuch, Food Research 12, 273 (1947). 



36 N. B. Guerrant, O. B. Fardig, M. G. Vavich, and H. A. Ellenberger, Ind. Eng. 

 Chem. 40, 2258 (1948). 



3' S. Brenner, V. O. Wodicka, and S. G. Dunlop, Food Technol. 2, 207 (1948). 



38 J. F. Feaster, M. D. Tompkins, and W. E. Pearce, Food Research 14, 25 (1949). 



39 B. B. Sheft, R. M. Griswold, E. Tarlowsky, and E. G. Halliday, Ind. Eng. Chem. 

 41, 144 (1949). 



^o R. Millares and C. R. Fellers, Food Research 14, 131 (1949). 



"1 P. F. Sharpe, J. B. Shields, and A. P. Stewart, Jr., Proc. Inst. Food Technol. p. 54 



(1945). 

 « A. F. Morgan, L. E. Kidder, M. liunner, B. K. Sharokh, and R. M. Chesbro, Food 



Research 14, 439 (1949). 

 « B. B. Cook, A. F. Morgan, and M. B. Smith, Food Research 14, 449 (1949). 



