UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 656 



Contribution from the Hureau of Chemistry 

 CARL L. ALSBERG, Chief 



J^^^J-U 



Washington, D. C. 



May 8, 1918 



CONCORD GRAPE JUICE: MANUFACTURE AND 

 CHEMICAL COMPOSITION. 



By B. G. Hartmann, Fermentation Chemist, and L. M. Tolman, Chief, Central Food 

 and Drug Inspection District. 1 



CONTENTS. 



Scope of the investigation 1 



Character of fruit used 2 



Manufacture of commercial Concord grape 



juice 4 



Crushing and stemming the fruit 6 



Heating the crushed fruit 6 



Pressing the heated fruit 9 



Sterilizing the juice and bottling it for 



storage 12 



Siphoning the juice 13 



Bottling and pasteurizing the trade juice. 17 



Page. 

 Manufacture of commercial Concord grape 

 juice— Continued. 



Manufacture of grape juice in the Lake 



Erie district 17 



Occurrence of small amounts of alcohol . . 18 

 Introduction of water during manufac- 

 ture 19 



Chemical composition of grape juice 20 



Methods of analysis 25 



Additional determinations 25 



Summary 26 



SCOPE OF THE INVESTIGATION. 



Although a large amount of work has been done on the chemical 

 composition of American grapes, and several bulletins on the subject 

 have been issued in the last few years by the Department of Agricul- 

 ture, the information presented is restricted principally to the acid and 

 sugar content of American grapes, and, in the main, is of interest 

 to viticulturists only. The literature appears to contain no specific 

 information concerning the manufacture and chemical composition 

 of commercial Concord grape juice. The purpose of the investiga- 

 tion, the results of which are embodied in this bulletin, was to obtain 

 information on the manufacture of Concord grape juice and to pro- 

 cure chemical data on authentic samples of this product. 



The first step of the work consisted in taking, under the super- 

 vision of a member of the Bureau of Chemistry, 5-gallon samples 



1 It is desired to express appreciation, for their cooperation, to Mr. B. B.Wilcox, who was in charge of 

 the work conducted at the factory in the Hudson River district, and to Mr. M. J. Ingle, who assisted in 

 the chemical analysis of the juices. 

 39092°— 18— Bull. 656 1 



