554 



CHEMICAL AND PHYSICAL BEHAVIOR OF CASEIN 



of isoelectric casein to bring it to the same pH. The curves for the 

 four alkaHes are identical (Fig. 4), thus pro\ang that Ca(0H)2 and 

 Ba(0H)2 combine with casein in equivalent proportion. Table I 

 gives the limits of pH between which the four metal caseinates are 

 completely soluble in a 1 per cent solution at room temperature. 



TABLE I. 



1 per cent Na caseinate completely soluble between pH 7.02 and > 12.20 



1 " " K " " " " " 7.09 " > 12.28 



1 " « Ca " " " " " 10.53 " > 12.00 



1 « « Ba " " " " " 10.50 " > 12.26 



.<0 



u 



o 

 o 



to 



1.4 



L3 



12 



1.1 



1.0 



0.9 



pH 6 7 8 9 10 11 12 



Fig. 6. Viscosity curves for Na caseinate and Ba caseinate. 



On account of the incomplete solubility of Ba caseinate and Ca 

 caseinate at a pH between 4.7 and 10.5 it is not possible to draw any 

 conclusion from the relative osmotic pressure or relative viscosity 

 of metal caseinates with monovalent and divalent cation between a 

 pH of 4.7 and 10.5 . This should be kept in mind in judging the curves 

 in Figs. 5 and 6. 



