for on it the food value of the fruits depends. To a certain extent, the
composition of all fruits is the same, but the varieties of this food
differ in their food values almost as greatly as do vegetables. Many of
them are extremely low in this respect, while a few of them are rather
high. In order to determine the place that fruit should have in a meal,
it is necessary to obtain a definite idea of the composition as well as
the food value of the different varieties.

12. PROTEIN AND FAT IN FRUITS.--Such small quantities of protein and fat
are contained in fruits that very little attention need be given to
these substances. Exceptions are found in avocados, or alligator pears,
and in ripe olives, both of which are high in fat. Then, too, there is a
small amount of protein in grapes and some other fruits, but it is not
sufficient to merit consideration.

13. CARBOHYDRATE IN FRUIT.--Whatever food value fruits may have, whether
it be high or low, is due to the carbohydrate they contain. Some green
fruits and bananas contain a very small amount of starch, but on the
whole the carbohydrate of fruits is in the form of sugar and is in
solution in the fruit juices. The chief form of this carbohydrate is
known as _levulose_, or _fruit sugar_. However, _glucose_, another form
of sugar, is also found in nearly all fruits, grapes and dried fruits,
such as figs, raisins, etc., containing an unusually large amount. In
addition, _cane sugar_ is contained in the majority of fruits. _Pectin_
is also a carbohydrate that is found in large quantities in some fruits,
while in other fruits it is lacking. This substance is related to the
gums and to cellulose. Although it is one of the carbohydrates from
which no food value is derived, it is of considerable importance,
because it is responsible for the jelly-making properties of fruits.