Gelling sugar or (British) Jam sugar or (US) Jelly sugar or sugar with pectin is a kind of sugar, which is used to produce preserves and which contains pectin as a gelling agent. It also usually contains citric acid as a preservative, sometimes along with other substances, such as sorbic acid or sodium benzoate
Gelling sugar from German suppliers comes in three different varieties, labeled 1:1, 2:1 and 3:1, where the first number indicates the amount of fruit to be used in relation to the sugar. The 1:1 appears to correspond to traditional British recipes for jam and marmalade and thus to jam sugar and the others are for lower sugar preserves. The higher the concentration of fruit is chosen, the more fruity and the less sweet the resulting taste will be. Gelling sugar 3:1 should be used with fully ripe and sweet fruits.
Gelling sugar can not be stored as long as normal sugar, because of its content in pectin.
Gelling sugar is different from preserving sugar, which does not contain pectin and is just sugar with larger crystals to avoid scum.