I\. OCdUKIACi: IN FOOD 



.V.M) 



The hiotiii coiitiMil of I'icsli cliccsc, with a raiijic ol 0.01 1 to O.OTH 7 per 

 liiani iiK rca.'^cs two- or t liicctold on ii|)ciiiiiti;, thi'oujili hactcrial synthesis." 



It is claimed that royal jelly is \-erv lich in hiotiii, contaiiiinji; 4.1 7 per 

 jiram: pollcMi and iioiiey contain 0.2") and O.OOOliO 7 per <>,iani, i-espcct i\-ely.''- 



Tlie l>iotiii content ot xai'ioiis food products as deterniined l)y ("heldelin 

 and Williams' in a larjie selection of samples for each food is <;'i\-en with 

 axerage \ahies in 'ral)le XI. 



Avidin, the only natural antihiotiii (see ]). .")"),■)) occui's in I'aw e<i;ji; white 

 and therefore would interfere with the estimation of hiotin in whole raw 

 ej;;^. (^uantitatix'e determinations of l)iotin and a\'idin in whole eji;jj; in which 

 (>ojr white and ejig yolk are thoroujiihly mixed inxariahly show an excess of 

 ax'idin, as illustrated liy the follow in<;- example:''' 



.■\vi(iin total. 

 free (A) + bound lAB) 

 7, nil. 



0.50 



.\vidin in form of 



biotin complex (AB) 



7/ ml. 



0.19 



Excess of 



free avidin (A) 



7/ml. 



0.31 



This conclu>ion was contirmed" intlirectly hy experiments in wiiich egj>; 

 white, egg yolk (of one egg), and mixtures of yolk and white in the pro- 

 portion found in the whole egg were analyzed, as shown by the following 

 \-alues: 



The hiotiii of egg yolk is present in a high molecular undialyzable and 

 in the .same time microl)iol()gically actix'e form (p. o,")")). This may explain 

 its independent existence in the faee of excess of avidin in the surrounding 



egg white. 



" R. \. Sulliv;iii. i:. Xifl.-^cii. ;iii(l .1. J.irinol, ./ . Sulrilinn 25. 4f)3 (lOi:^), 

 '2 G. Kitzes, H. .\. Sfhiicltc, and C". .V. Klvchjcm, J . Xutrition 26. 241 (WV.U. 

 '» P. Gyorgy and C. S. Rose, Froc. Soc. Expll. Biol. Med. 49, 204 (1942). 

 '■* V. P. S^-dprmtrickor, SoiinN/i )nril. c^pafiol . 6. 3.56 (1043). 



