FRUIT AS FOOD 
may be seen from Table I such fruits 
as strawberries, blackberries, and rasp- 
berries would be included in the first 
class, and fresh figs, bananas, grapes, 
etc., in the second. In dried fruits which 
have been concentrated by evaporation the 
percentage of nutrients is very much high- 
er than in fresh fruits. Some preserved 
fruits also possess a comparatively high 
nutritive value, owing to the evapora- 
tion of water by the heat of cooking or 
to the addition of sugar, or to both 
factors. Candied fruits, such as cher- 
ries and apricots, which are included in 
the table, may be looked upon as typical 
examples of this class of fruit products. 
As regards composition, the water con- 
tent is low and the carbohydrates and 
consequently the energy value is very 
high, owing to the added sugar. 
Olives and the avocado are remarkable 
for the large percentage of fat which 
they contain, but in general it may be 
said that this constituent is present in 
very small proportion in fresh fruits. 
In the case of the apple, pear, etc., it 
seems probable that the small amount of 
fat obtained in chemical analysis con- 
sists of the coloring matter contained 
in the fruit or of wax found in the skin. 
That the amount of wax may be consid- 
erable is evident when we recall the fact 
that fruit wax is collected from bay ber- 
ries and other fruits in quantities suf- 
ficient for candle making and other pur- 
poses. That common fruits actually con- 
tain fat, though it is not generally as- 
sociated with them, is shown by a re- 
cently published study of the fat of 
woods strawberries. The dried berries 
when extracted yielded a small amount 
of oil, cloudy at ordinary temperatures, 
but clear when heated, and much like 
linseed oil in its properties. 
In the majority of fruits and fruit 
products the carbohydrates are the food 
constituents most abundantly represent- 
ed. The figures in the table show that 
the proportion of nitrogen-free extract 
varies greatly, being lowest in the fresh 
and highest in the dried and preserved 
fruits. It is interesting to consider also 
the values which have been reported for 
2—25 
L041 
some of the constituents not shown in 
the table, but included in the group 
“nitrogen-free extract.” In seeds which 
are commonly eaten, such as the cereal 
grains, and beans, peas, and other 
legumes, the nitrogen-free extract is quite 
largely made up of starches. In fruits, 
however, sugars and the so-called pectin 
bodies, with very often more or less 
starch, make up the group. The princi- 
pal sugars in fruit are cane sugar, grape 
sugar (glucose), and fruit sugar (levul- 
ose), the last two being usually pres- 
ent together in equal quantity and 
designated invert sugar or reducing 
sugar. The stage of growth and the de- 
gree of ripeness have a very marked ef- 
fect on the kind and amount of sugar, 
and it is therefore difficult to give aver- 
age figures for the quantities present 
which will be fairly representative. An 
idea of the range in the sugar content of 
ripe fruits may be gathered from figures 
quoted from a summary* published sev- 
eral years ago. According to these data, 
invert sugar ranged from 2 per cent in 
round numbers in large early apricots 
to 15 per cent in grapes and a variety of 
sweet cherries. A number of fruits 
(strawberries, gooseberries, raspberries, 
and apples) contained about half the 
latter quantity. The cane sugar ranged 
from less than 1 per cent in lemons to 
14 per cent in a variety of plums. 
Bananas also contained a fairly high per- 
centage, namely, 11 per cent. 
Fruit sugar rarely occurs unaccom- 
panied by grape sugar, but has been thus 
reported in the mango and in amounts 
large in proportion to the grape sugar 
in sweet apples and sweet pears and a 
number of varieties of grapes. In the 
case of grape sugar large amounts—18 
to 30 per cent—have been reported in 
juice of different sorts of grapes, while 
in dried fruits the values are even high- 
er, 32 per cent having been found in 
prunes, 54 per cent in Zante or “English” 
currants, which are of course a small 
seedless grape, 61 per cent in raisins, 48 
per cent in figs, and 66 per cent in dates. 
*Tippman: Chemie der Zuckerarten, 1895, 
third edition, pages 4938, 591; 1904, fourth 
edition, pages 200, 794. 
