UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 666 



Contribution from the Bureau of Chemistry 

 CARL L. ALSBERG, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



May 9, 1918 



THE EFFECT OF ALKALI TREATMENT ON COCOAS. 



By Eugene Bloomberg, formerly Assistant Chemist, Buffalo Food and Drug 



Inspection Station. 



CONTENTS. 



Page. 



Purpose of the investigation 1 



Description of investigational samples 3 



Analyses of untreated and treated cocoas 4 



Water-soluble matter in untreated and treated 



cocoas 9 



Composition of the water-soluble matter in 



untreated and treated cocoas 14 



Page. 

 Ash ratios in untreated and treated cocoas. . . 16 



Action of various alkalies on cocoas 18 



Appearance of the cocoas 19 



Conclusions 20 



PURPOSE OF THE INVESTIGATION. 



IN THE PROCESS of the manufacture of cocoa, the cocoa beans 

 are roasted, the shells removed, the nibs crushed in a mill, and the 

 resultant product placed in a press whereby a part of the cocoa 

 butter is removed. The press cake . is then ground and sifted to 

 form the cocoa of commerce. By the removal of this portion of fat 

 the color of the cocoa is made considerably lighter. For many years 

 it has been the endeavor of manufacturers of cocoa to darken the 

 color of the cocoa so that it would more closely resemble chocolate. 

 This effect has been sought in various ways, but the most prevalent 

 method is by the addition of alkalies or alkaline carbonates. Am- 

 monium carbonate and magnesium carbonate have also been used 

 with this end in view. In this article the term "alkali treatment" 

 will be understood to include the treatment of cocoa not only with the 

 alkalies or alkaline carbonates, but also with such salts as am m onium 

 carbonate and magnesium carbonate. This process is quite generally 

 known as the "Dutching" process, and the cocoas made therefrom 

 as "Dutched" or "Dutch process" cocoas. The name is derived 

 from the fact that this method of treating cocoa originated in Holland. 

 Attempts have been made at various times to develop this en- 

 hanced color by means other than the addition of chemicals. Treat- 

 ment with steam, under pressure; wetting the cocoa and allowing 



45789°— 18— Bull. 666 1 



