20 
BULLETIN 859, U. S. DEPARTMENT OF AGRICULTURE. 
the first stage analyzed. The possibility should be borne in mind 
that the ripe tomato may contain relatively more acid salts and less 
free acid than the green fruit. Since the acid content was deter- 
mined throughout by titration to neutrality, with phenolphthalein 
as the indicator, it is obvious that the presence of acid salts might 
cause the analytical results to shoAv more acid than the taste would 
indicate. As will be seen later, the change in the ratio of acid to 
sugar is in the direction to account for the sweetening that takes 
place during ripening. 
Nevertheless it is not 
impossible that the 
ratio of free-acid salts 
is likewise of impor- 
tance. 
It is believed that 
rainfall and other 
factors influence the 
quantity of acid in 
tomatoes, although 
there are few ana- 
lytical data at hand 
to indicate this. In 
the fourth column of 
figures of Table IV 
(sec. B), concerning 
the tomatoes that 
received the highest 
rainfall, the acidity 
is 15.88 per cent, and 
in the fifth column, 
where the tomato 
would no doubt be 
still affected, there 
Fig. 3.— "Diagram showing the progressive changes in the composition is a decrease to 11.11 
of Livingston Globe tomatoes during ripening. The percentages are 
based upon dry weight. Curve a-a, acid; 6-6, pentosans; c-c, crude 
fiber; d-d, crude ash; e-e, starch; /-/, protein; g-g, soluble carbohy- 
drates (total sugar); h-h, insoluble carbohydrates; i-i, total carbo- 
hydrates; j-j, sugar-free solids. 
In this connection 
it may be worth while to suggest that a tomato with excessive water 
content may have the intercellular spaces sufficiently diminished so 
that gas exchange is impeded. Under such conditions a deficiency 
of oxygen might result in an accumulation of acid, due to incomplete 
oxidation of carbohydrates to carbon dioxid. 
The most striking change during ripening is that undergone by 
carbohydrates. In the first stage analyzed it was noticed particu- 
larly that insoluble carbohydrates composed 52.1 per cent of the 
per cent, but this fig- 
ure is higher than the 
remaining ones. 
