JOIMAL OF AGEIOJLTIAL RESEARCH 



DEPARTMENT OF AGRICULTURE 



Vol. VI Washington, D. C, April 17, 1916 No. 3 



DETERMINATION OF STEARIC ACID IN BUTTER FAT* 



By E. B. Holland, Associate Chemist, and J. C. Reed and J. P. Buckley, Jr., 

 Assista7tt Chemists, Massachusetts Agricultural Experiment Station 



INTRODUCTION 



Oils and fats are composed largely of neutral glyceryl esters together 

 with small amounts of free fatty acids and unsaponifiable matter. 

 Formerly the esters were considered simple glycerids, compounds of 

 glycerol and three radicals of the same fatty acids. At present the oppo- 

 site view seems to prevail and mixed glycerids are said to predominate 

 in most products. The subject is controversial and difficult of solution. 

 The constituents would be the same, however, in either case, whether 

 combined as simple or complex molecules. The object of a technical 

 examination of oils and fats is to isolate, identify, and determine the 

 various fatty acids, glycerol, and unsaponifiable bodies, although, as 

 Lewkowitsch asserts, this is not attainable in the present state of our 

 knowledge. Certain progress has been made in determining different 

 constituents of fats by indirect methods, such as iodin absorption, acetyl 

 number, and molecular- weight calculations. Direct methods of fractional 

 distillation, crystallization, and solubility of various salts have not, as a 

 rule, proved sufficiently discriminative for quantitative use. 



Fatty acids constitute about 95 per cent of most oils and fats and 

 characterize the products to a large extent. The necessity of accurate 

 methods for the quantitative determination of these acids has long 

 been recognized not only from the standpoint of pure science but espe- 

 cially in physiological studies having as the object the measurement of the 

 effect of different food groups on the production of body and milk fats. 

 Many methods have been proposed since the publication of the work of 

 Chevreul nearly 100 years ago, but few, if any, have met with general 

 approval. After several years' investigations of the Partheil and Ferie 

 method (7),^ which proved unsatisfactory in the authors' ^ hands, a study 

 of methods for determining stearic acid in butter fat was undertaken. 



' From the Department of Chemistry, Massachtisetts Agrictdttiral Experiment Station. Printed with the 

 permission of the Director of the Station. 

 * Reference is made by number to " Literature cited," p. 113. 

 ' Mr. Reed was associated with the senior author in the earlier stages of the work and Mr. Buckley in the 



later. 



Journal of Agricultiu-al Research, Vol. VT, No. 3 



Dept. of Agriculture, Washington, D. C. Apr. 10, 1916 



db Mass. — i 



(lOl) 



