INTERNATIONAL CONGRESS OP VITICULTURE 



I. THE SUGAR AND ACID CONTENT OF AMERICAN 

 NATIVE GRAPES. 



By WILLIAM B. ALWOOD, 

 Stonehenge, Rio Road, Charlottesville, Virginia. 



For several years the writer has carried on an investigation to determine 

 the sugar and acid content of our native grapes. This work was done under 

 the direction of the Bureau of Chemistry, United States Department of Agri- 

 culture. The results have been published somewhat in extenso by the De- 

 partment of Agriculture. This paper deals with a summary of the results 

 for sugar and acid in ripe grapes and the varying ratios of these two sub- 

 stances from year to year. Only eight varieties are included in this discus- 

 sion because these comprise those most generally grown for commercial 

 purposes. 



The fruit of the grape as a food, or as raw material for the manufacture 

 of wine, or of unfermented grape juice, is valuable in proportion to the total 

 sugar content and the balanced ratio of its acid content to the sugar. It is 

 true that there are special qualities in the nature of the fruit, as flavor, 

 etc., which contribute to its palatability for food as fresh fruit, or for the 

 manufacture of wine or unfermented grape juice, but the essential value, 

 after all, is most readily based upon the sugar content and the proper balance 

 of the acid and sugar. The question of acceptable or non-acceptable flavor 

 of the fruit is usually settled at the very inception of a new variety. Those 

 which have not sufficiently desirable flavors are not propagated or widely 

 disseminated for commercial purposes. 



Prior to the commencement of this investigation in 1907, there was very 

 little data on the composition of American native grapes available. 



The purpose in undertaking this work was not abstract investigation 

 but to furnish information of practical value. The chemical examination 

 of the fresh fruit was carried on principally at Sandusky, Ohio, but also 

 a considerable number of samples were analyzed at Charlo_ttesville, Va. 

 The samples have been secured from growers direct and also from the 

 stock as it arrived at the wine cellars and juice factories. Records of the 

 samples have been kept in such manner as to identify the variety and in 

 nearly every instance the farm where grown. While samples were examined 

 from all the eastern grape growing districts, this paper includes data only 

 of fruit grown in two districts, viz: Northern Ohio including the islands 

 in Lake Erie, and samples from Charlottesville, Va. The reason for using 

 only these results is that the sampling was more perfectly done within this 

 territory and experiments in making pure wines were confined to grapes 

 grown in those two districts. 



The sample taken for analysis consisted of about four pounds of fruit, 

 which was crushed by hand in a porcelain dish and then the juice strained 

 off through a double thickness of cheese cloth and eventually the pulp was 

 pressed firmly by hand until it was as dry as usually pressed at the wine 



