June i5,1925 Environment and Chemical Composition of Grape Juices 1153 
tent in a given variety fluctuate entirely 
independently or with some degree of 
correlation. Muller-Thurgau (48) re¬ 
garded the increase of sugar and reduc¬ 
tion of acidity in ripening fruits not as 
inseparably related processes but as in¬ 
fluenced by conditions such as tempera¬ 
ture, water, and nutrient supply, leaf 
area, and size of crop on the vines, 
which influence the rate of metabolic 
processes. Ivelhofer (38) published a 
graph summarizing the records for 
sugar and acid content of Raiichlings 
grapes for the 14 years 1891-1904, in¬ 
clusive. Years of maximum acid con¬ 
tent were also years of minimum acid 
content, and vice versa. Years of 
maximum sugar content for the period 
in a large number of varieties. These 
years were also characterized by mini¬ 
mum acid content for the period in a 
large number of varieties. On the 
other hand, 1922 and 1920 were years 
of low sugar content, very few varieties 
reaching their maximum or next to 
maximum sugar, and both years are 
characterized by the almost total 
absence of low acid readings and the 
large number of maximum or next to 
maximum figures found. Furthermore, 
1921 is notable for the absence of either 
very high or very low figures for either 
constituent. The general conclusion 
to be drawn from the graph is that a 
Sugar and Acid Content of 49 Varieties of Grape3 
1913-1323 
1319 
rTTmTTTTT 
S58 
5a^a.r 
TT 
T 
Jbl 
Ji 
M 
liiilL 
'////.sY/z -■= 
1920 
EM 
13 
mirnmmm 
===10 = 
Su3<x 
Acid 
1821 
1922 
10 
*iri 
m 
m 
2 III 
ills 
IE 
Wffff/A 2 'f/A/ZAA -- — i o 
19 
I - 
IF 
! jul 
11 
....llaS 
1923 
18 
riiiiliiiiiiiilliiiifiiliiiilli 
Acid 
The ^5 G ' lri H 
■maximum for ttie period Y///#/A 5^ highest for He period 
highest for He period . j==| 4$ h ighest for He period 
minimum for flic period 
Fig. 1.—Sugar and acid content of grapes, 1919-1923 
medium or average sugar content were 
years of medium acid content. No 
American studies upon this matter have 
been found in the literature. It is very 
important that the facts upon this 
point be known and understood, since 
the palatability of an unfermented 
juice, like that of a wine, depends in no 
small degree upon the sugar-acid ratio. 
The results of the present study, in so 
far as they bear upon the acid-sugar 
relation, are brought together graphi¬ 
cally in Figure 1. From an inspection 
of the graph it will be immediately evi¬ 
dent that 1923 and 1919 were years 
characterized by maximum or next to 
year of high sugar content is also one 
in which acidity is low, and conversely 
that a year which is markedly low in 
sugar content is one of more than aver¬ 
age acidity. This is very clearly the 
general situation. There are a number 
of exceptions: Maximum acid and max¬ 
imum sugar occur together in Catawba, 
Franklin, Herbemont, Isabella, Jeffer¬ 
son, and Noah in 1923, in Berckman 
and Cynthiana in 1922, in Goethe in 
1921, and in Montefiore in 1919. Mini¬ 
mum sugar and minimum acid occur 
only in Dakota and Herbert in 1919 and 
in Lampasas and Martha in 1922. 
There are a large number of cases in 
