UNITED STATES DEPARTMENT OF AGRICULT 
% BULLETIN No. 656 
Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 
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 
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 
