Marmalade is a fruit preserve made from the juice and peel of citrus fruits boiled with sugar and water. It can be produced from kumquats, lemons, limes, grapefruits, mandarins, sweet oranges, bergamots and other citrus fruits, or any combination thereof.The benchmark citrus fruit for marmalade production in Britain is the Spanish Seville orange, Citrus aurantium var. aurantium, prized for its high pectin content, which gives a good set.