PROCESS OF RIPENING IN THE TOMATO. 9 
Congdon (15) differs from Bacon and Dunbar (6) and claims that 
the acids are oxalic, citric, and a very slight amount of malic. 
Oxalic acid is supposed to predominate. 
The preponderance of opinion seems to be that the chief acid in 
the tomato is citric. 
With regard to the kind of sugar occurring in the tomato there is 
more uniformity of opinion. Patterson (36) says: 
A few samples of tomatoes were examined for both classes of sugars, the glucose 
being determined in solutions made up without application of heat; and then a por- 
tion of this solution was made up in the usual manner for the cane-sugar determina- 
tions. The amount of increase indicating cane sugar was so small that it was thought 
to be probably due to substances of a gummy or pectose nature, which are well under- 
stood to form sugars which act on Fehling's solution when treated with mineral acids. 
And from the amount of free acid in the tomato, cane sugar would not be likely to 
exist to any extent. 
Briosi and Gigli (13) believe that levulose is the sugar to which the 
sweetness of the yellow juice is chiefly due. 
Alwood and Bowman (4) say that "it is very probable that no 
other sugars than those of the glucose kind exist in tomatoes." 
Snyder (46), however, reports the presence of reducing and non- 
reducing sugars. 
Stuber (50) finds no change in the sugar content of sugar samples 
before and after inversion. 
Albahary (2) presents data showing the presence of cane sugar. 
Bacon and Dunbar (6) make the following statement: 
A number of experiments have shown that the sugar of tomatoes is usually invert 
sugar, with at times a slight excess of levulose. 
Thompson and Whittier (51) were unable to find sucrose in either 
green or ripe fruits, but reported approximately equal quantities of 
levulose and dextrose, concluding that in the classification of fruits 
according to the kind of sugar present the tomato falls in the invert- 
sugar group. One of the more recent investigators, Bigelow (11), 
shows that sucrose is probably absent. He states: 
It is probable that the sugar in tomatoes is all invert sugar. This was indicated by 
some samples which were examined, in which the determination of sugar before and 
after inversion gave the same results. 
The work herein reported supports the contention of most scientific 
workers that little or no cane sugar is present in the tomato. It is 
very probable that where small amounts of sucrose are indicated by 
the increased reduction of Fehling's solution after acid hydrolysis 
that the increased reduction is due to other substances than invert 
sugar. 
Since the data of the present investigation concern the percentage 
composition of the entire fruit, the comparable results of previous 
analyses of the whole tomato have been assembled in Table II. 
175085°— 20— Bull. 859 2 
