20 



BULLETIN 859, TJ. S. DEPABTMENT 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 show more acid than the taste woidd 

 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 

 is a decrease to 11.11 

 per cent, but this fig- 

 ure is higher than the 

 remaining ones. 

 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 



Fig. 3. — "Diagram showing the progressive changes in the composition 

 of Livingston Globe tomatoes during ripening. The percentages are 

 based upon dry weight. Curve a-a, acid; 6-6, pentosans; c-f, crude 

 fiber; d-d, crude ash: c-c, starch; /-/, protein; g-g, soluble carbohy- 

 drates (total sugar); h-h, insoluble carbohydrates; i-i, total carbo- 

 hydrates; j-j, sugar-free solids. 



