SUGAR AND ACID IN GRAPES DURING RIPENING. 



19 



Some interesting points are brought out by comparing the sugar 

 and acid content from the date when all the berries were colored 

 until fully ripe. The note "Berries, colored" is necessarily some- 

 what arbitrary, because the coloring of these varieties is not at all 

 alike; but we have used it in the general sense understood by the 

 grape growers. These comparisons are presented in Table 2: 



Table 2. — Increase of sugar and decrease of acid for certain periods, 1911. 



[Results in gram? per 100 cc.J 



SANDUSKY, OHIO. 



Variety and date. 



Condition of 

 berries. 



Days 

 elapsed, 



Total 

 sugar. 



Gain of 



sugar. 



Total 

 acid. 



Loss of 

 acid. 



Ratio loss 



of acid to 



gain of 



sugar. 



Acid- 

 sugar 

 ratio in 

 ripe fruit. 



Catawba: 



Aug. 27. 



Oct. 4... 

 Clinton: 



Aug. 23. 



Oct. 8. . . 

 Delaware: 



Aug. 20. 



Sept. 17. 

 Ives: 



Aug. 13. 



Sept. 20. 

 Norton: 



Aug. 30. 



Sept. 27. 



Berries, colored. 

 Wine-ripe 



Berries, colored. 

 Wine-ripe 



Berries, colored. 

 AVine-ripe 



Berries, colored. 

 Wine-ripe 



Berries, colored. 

 Last sample ' . . 



11.58 

 19.45 



15.55 

 21. 17 



18.21 

 24.46 



11.31 

 17.36 



15. 96 

 22.67 



| 7.87 



| 6.62 



| 6.25 



\ 6.05 



| 6.71 



2.21 

 .95 



2.28 

 1.49 



.96 

 .60 



1.31 

 .70 



2.11 

 1.34 



} • 

 } ■ 

 } ■ 

 } • 



1.26 

 .79 

 .36 

 61 



6.2 

 7.1 

 17.4 

 9.9 



8.7 



1:20.5 

 1:14.2 

 1:40. 8 

 1:24. 8 

 1:16.9 



CHARLOTTESVILLE, VA. 



Concord: 



Aug. 12. 



Aug. 26. 

 Cynthiana: 



Aug. 16. 



Sept. 15. 

 Delaware: 



Aug. 5.. 



Aug. 26. 

 Norton: 



Aug. 16. 



Sept. 19. 



Berries, colored. 

 Wine-ripe 



Berries, colored. 

 Wine-ripe 



Berries, colored. 

 Wine-ripe 



Berries, colored. 

 Wine-ripe 



14.30 

 17.36 



15.60 

 21.66 



16.44 

 25.80 



16.57 

 21.92 



| 3.06 



| 6.06 



} 9.36 



| 5.35 



/ 0.98 



\ .53 



/ 2.03 



\ .75 



f 1.32 



\ .65 



{ 



2.13 

 .80 



| 0.45 



; „ 



} ., 



} 



1.33 



1: 6.8 

 1: 4.7 

 1: 13. 9 



1: 4.02 



1:32.8 

 1:28.8 

 1:39.7 

 1:27.4 



1 Fruit was not fully ripe. 



The summary of the data given in Table 2, on changes in sugar and 

 acid content of these varieties from the time the berries were colored 

 until wine-ripe, show striking differences in the ratios, loss of acid to 

 gain of sugar, and total acid to total sugar, at full ripeness. The 

 greatest loss of acid to gain of sugar, hence the lowest ratio, is shown 

 by Cynthiana and Norton at Charlottesville, and Catawba at San- 

 dusky. The full data given in Table 1 show in detail the develop- 

 ment of these varieties and that when ripe they gave an excellent 

 juice for wine making. The ratio for these three varieties as to total 

 acid and sugar when fully ripe show that the Catawba at Sandusky 

 was not so well balanced in acid and sugar content as the Cynthiana 



