150 THE BOOK OF BUTTER 



facturing process. According to Van Slyke and Hart, 1 

 " Mottles in butter are due primarily to the presence and 

 uneven distribution of buttermilk adhering to the outer 

 surface of the small granules; and, secondarily, to the 

 hardening and localizing effect of the salt brine upon the 



FIG. 48. A mottled butter. 



proteid of the buttermilk thus retained in butter. The 

 light portions of mottled butter owe their lighter color 

 to the presence of localized proteid (usually casein lactate). 

 The yellow or clear portions occur where the spaces 



1 Van Slyke, L. L., and Hart, E. B., The Proteids of Butter in 

 Relation to Mottled Butter, N. Y. Agri. Exp. Sta., Bui. 263, p. 70, 

 1905. 



