Fruit Jellies and Gelatine

When using gelatine in desserts it is important to bear in mind that an enzyme in some raw fruit and fruit juices breaks down the protein in gelatine and reduces its setting qualities. The gelatine may set initially, but then, on standing for 24 hours, the mixture softens. Raw pineapple and papaya and unheated lemon juice all have this effect. Heating destroys the enzyme, so in pasteurized juices and canned fruits, the enzyme has been destroyed, eliminating the setting problem.