FRUIT AS FOOD 
gar being one of the sorts which is rath- 
er favorably known in regions where this 
fruit is grown. The acid juice of lemons 
and limes is used like vinegar as a con- 
diment, and many persons consider that 
lemon juice is more delicate. It is some- 
times claimed that it is more wholesome 
also, but this seems hardly more than a 
matter of opinion, as there is no reason 
to suppose that the small amounts of 
vinegar ordinarily used are in any way 
harmful. 
Verjuice, the expressed acid juice of 
green apples, crab apples, or other un- 
ripe fruit, was formerly used as a con- 
diment and was greatly prized. It has 
survived in modern cookery in a limited 
way and may occasionally serve a use- 
ful purpose when lemon juice is not read- 
ily obtainable. 
Ripening and Its Effect on Composition 
As fruits grow to their full size and 
ripen they undergo marked changes in 
chemical composition with respect both to 
the total and to the relative amount of 
the different chemical bodies present. 
When stored after gathering, the changes 
continue, some fruits improving on stor- 
age and others deteriorating very rapid- 
ly. In general, ripe fruits are less acid 
than green and contain less starch, woody 
material, crude fiber, and the carbohy- 
drates commonly referred to as pectin 
bodies and correspondingly larger 
amounts of the different sugars. 
Fruits contain oxydases and other fer- 
ments, and these are believed to play a 
very important part in the chemical 
changes which accompany growth and 
maturity. Many diverse views have been 
expressed regarding the exact nature and 
extent of the processes involved and the 
compounds formed in ripening fruit. The 
question as a whole has been a favorite 
one with chemists, and the agricultural 
experiment stations have made a number 
of important contributions to the sub- 
ject. One of the most recent and valu- 
able contributions, both from a biblio- 
graphical and from a chemical stand- 
point, is the series of investigations pub- 
1043 
lished by Bigelow * and his associates, of 
the Bureau of Chemistry of the Depart- 
ment of Agriculture, on the ripening of 
winter and summer apples and of 
peaches. With winter apples it was 
found that the starch increases from 
early summer until the maximum is 
reached in midsummer and then decreases 
and finally disappears. The malic acid 
content decreases from early summer un- 
til maturity, while cane sugar and in- 
vert sugar increases. 
In the case of peaches, as the fruit de- 
velops from early summer to ripeness the 
proportion of flesh increases and the pit 
decreases. During this period the weight 
of reducing sugars increases about eight 
times and that of cane sugar or sucrose 
and acids considerably more than this. 
An increase is also noted with the vari- 
ous forms of nitrogenous substances. 
Throughout the whole period of growth 
the proportion of solids to water in the 
flesh of the peach remains fairly con- 
stant. The pit, on the other hand, be- 
comes harder and the percentage of water 
in it decreases as growth progresses. It 
is interesting to note that throughout the 
whole period of growth no appreciable 
amount of starch is found in the peach. 
Between the condition known as market 
ripeness and full ripeness considerable 
growth takes place in the peach, there 
being an increase in both water and solid 
matter and in reducing sugar and cane 
sugar. A German investigator} found 
that when black currants were picked 
when slightly green and kept for a few 
days there was an increase in sugar and 
a decrease in the acid content. The 
changes which take place in gooseber- 
ries do not appear to be of the same 
character. Picked when green, they con- 
tain 3.9 per cent sugar and 27.2 per cent 
acid. When stored at a cool temperature 
for six days they had taken on the dark 
color of ripe berries and contained some- 
what smaller proportions of both sugar 
and acid. 
A knowledge of the changes which ac- 
company the growth, ripening, and stor- 
*U. 8S. Department Agriculture. Bureau of 
Chemistrv Bulletins No. 94 a 
97 
+ Landw. Jahrb. Schweiz., aro (1905), p. 600. 
