26. To prevent the creaming or the crystallizing of such candy as taffy,
an acid of some kind is generally used with the cane sugar in the making
of this variety of confection. The acid, upon being boiled with the
sugar, changes a part of the cane sugar to invert sugar, and as this
does not crystallize, the candy will not become sugary. A similar effect
is obtained by adding glucose in sufficient amounts; since it does not
crystallize, the cane sugar is prevented from becoming sugary.
27. The acids most commonly used for this purpose are cream of tartar,
acetic acid, vinegar, which has acetic acid for its basis, and lemon
juice, which has citric acid for its basis. With each pound of sugar, it
will be necessary to use 1/8 teaspoonful of cream of tartar, 1 or 2
drops of acetic acid, or 1 tablespoonful of vinegar or lemon juice in
order to prevent crystallization. Lemon juice and vinegar are much more
likely to flavor the candy than are cream of tartar and acetic acid.
Often, if a fine-grained creamy candy is desired, a small amount of one
of these acids is used. Even in small quantities, they will prevent the
coarse-grained crystallization that is the natural result of the cooking
and stirring of the cane sugar when nothing is done to prevent it.