8. JELLY MAKING consists in cooking fruit juice with sugar until, upon
cooling, it will solidify, or jell. While this is not a difficult nor a
complicated process, there are some housewives who do not have success
with it. Often the result may be very good when a certain fruit is used,
whereas it may be entirely unsatisfactory at another time, even though
the same fruit is used and practically the same procedure is followed.
If the best results are to be assured in jelly making, the principles
that are involved in this process must first be thoroughly understood
and then the correct procedure must be painstakingly followed out.
9. To solidify properly and thus become a desirable jelly, the fruit
juice that is used for this purpose must have the following
characteristics and treatment: (1) it must contain certain jelly-making
properties; (2) it must be extracted properly; (3) it must be combined
with the correct proportion of sugar; and (4) it must be cooked the
proper length of time. There are, of course, numerous degrees of
solidity of jelly, varying from that which will barely retain its shape
to that which is very tough and hard, but neither extreme is desirable.
To be right, the jelly should be firm enough to stand up well, but
should be tender and soft when a spoon is cut into it.
10. Fruit is the principal ingredient in the making of jelly, as it is
the source from which the juice is obtained. Such imperfections in
fruits as poor shape or unattractive appearance do not count in this
matter, since only the juice is used; but they must contain jelly-making
properties in order that jelly can be made from them.
Green or slightly unripe fruits are better for jelly making than fruits
that have become ripe. In fact, when in this immature state, fruits may
be used to make jelly, whereas the same fruits, when perfectly ripe,
often will not make jelly at all, or, if they do, will produce a jelly
that is inferior in quality.
11. The chief requirement of fruits that are to be used for jelly
making is that they contain acid and pectin. _Pectin_ is the real
jelly-making property of fruits. When it is in the presence of acid and
combined with the correct proportion of sugar and the combination is
properly boiled, a desirable jelly is the result. Without pectin,
however, it is impossible to make the juice solidify, or jell. Pectin is
closely related to the carbohydrates, but as it does not yield heat
energy nor build tissue, its food value is not considered. In this
respect, it is like the cellulose of fruits and vegetables.
It is because green fruits contain more pectin than do ripe fruits that
they are more suitable for jelly making. The lack of either acid or
pectin need not, however, prevent the making of jelly from fruits, such
as sweet fruits, that contain other jelly-making properties, for either
or both may be supplied from some other source. In other words, jelly
may be made from any fruit that will yield juice and flavor.