Jelly making is a good way to preserve fruit flavors for enjoyment throughout the year. Ingredients Substances essential for fruit jelly making are fruit flavor, pectin, sugar, acid, and water. A pectin gel or jelly forms when a suitable concentration of pectin, sugar, acid, and water is achieved. For some fruit jelly, a mixture of different fruit juices is used. The fruit juice may also supply some or all of the pectin and acid.
Fruit juice is the source of water in jelly.
Pectin provides the three dimensional structure which results in a jellied product. Pectin is formed from a parent compound, protopectin, during the ripening of fruit and during the cooking of underripe fruit to extract juice. Fully ripe fruits contain less pectin than partially ripe fruits. For this reason, some jelly recipes specify the use of a portion of underripe fruit. All fruits contain some pectin.