Pectin is a soluble carbohydrate that is found naturally in fruits. At high temperatures, combined with sugar, this forms the setting agent for jam.

Fruits have different amounts of naturally occuring pectin – apples, gooseberries, currants (red/black/white), grapes and plums have relatively high natural pectin levels. Rhubarb, blueberries, strawberries and raspberries have much lower natural pectin levels.