A jellied fruit product requires proper amounts of fruit, pectin, acid, and sugar.
Fruit gives each product its flavor and furnishes at least part of the pectin and acid required for a successful gel. Highly flavored varieties of fruits are best for jellied products because the fruit flavor is diluted by the large proportion of sugar necessary for proper consistency and good keeping quality.
Pectin is the gum in the cell walls of a plant that is primarily responsible for gel formation. Some kinds of fruit have enough natural pectin to make a high-quality product. Others require added pectin, particularly when they are used for making jelly, which should be firm enough to hold its shape. All fruits have less pectin when they are fully ripe than when they are under ripe.
Acid is needed for flavor and for gel formation.
The acid content varies in different fruits and is higher in under ripe than in fully ripe fruits. For fruits that are low in acid, you can add lemon juice or citric acid. Also, commercial fruit pectin’s contain some acid.
Sugar helps in gel formation, serves as a pre- serving agent and adds to the flavor of the jellied product. It also has a firming effect on fruit, which is useful in the making of preserves.
Beet and cane sugar can be used with equal success. Although they come from different sources, they have the same composition. Corn syrup or honey can replace part of the sugar, but not all.