Which fruits need added pectin and which do not?
The high, medium and low pectin fruits, what to add to each, and why some jams set on their own and others never will.
- Difficulty
- beginner
- Time
- 5 min
- Read
- 3 min
Short answer
Apples, gooseberries, currants, damsons, plums, quince and citrus are high in pectin and set on their own. Apricots, raspberries and blackberries are middling. Strawberries, cherries, rhubarb, pears, peaches and figs are low and need lemon juice plus either added pectin, jam sugar, or a high-pectin fruit blended in.
Pectin is a carbohydrate in the cell walls of fruit. Some fruits carry a great deal of it, some almost none, and the amount also falls sharply as fruit ripens — which is why slightly underripe fruit sets better than a bowl of perfectly soft strawberries. Knowing where your fruit sits tells you before you start whether you need to add anything.
Step by step
- Learn the high-pectin list.Cooking apples, crab apples, gooseberries, blackcurrants, redcurrants, damsons, most plums, quince, cranberries, and citrus peel and pith. These set readily with just sugar and their own acid, and often need no lemon at all.
- Learn the middling list.Apricots, raspberries, blackberries, greengages, loganberries, ripe plums, elderberries. These usually set with the addition of lemon juice alone — one to two tablespoons per kilogram of fruit.
- Learn the low-pectin list.Strawberries, cherries, rhubarb, pears, peaches, nectarines, figs, marrow, melon, and any very ripe fruit. These need lemon juice and a pectin source, or they will make syrup no matter how long you boil them.
- Use slightly underripe fruit for a quarter of the batch.Pectin is highest just before full ripeness and falls off quickly afterwards. Keeping some firmer fruit back is free pectin and it also keeps the flavour brighter.
- Pick a pectin source that suits the jam.Jam sugar is the easiest — sugar with pectin and acid already in it. Commercial liquid or powdered pectin gives more control. Home-made apple pectin stock adds no flavour of its own to speak of. Or simply blend in a high-pectin fruit: strawberry and gooseberry, rhubarb and orange, pear and apple.
- Test rather than trust the list.Seasons and varieties vary. The cold saucer test on a frozen plate is the only thing that tells you whether this particular batch has set, whatever the fruit was supposed to do.
Tips
- Pectin needs acid to gel. A high-pectin fruit that is also low in acid — some sweet plums, ripe quince — still wants lemon juice.
- Apple pectin stock is a free by-product of any apple glut: simmer whole apples with cores and skins in water until collapsed, strain overnight through muslin without pressing, then freeze in ice cube trays.
- There is no pectin in the flesh of a lemon that matters much — it is the pith and pips that carry it, which is why marmalade recipes tell you to tie the pips in muslin and cook them with the fruit.
Common mistakes
- Using overripe fruit because it needs using up — Overripe fruit is exactly when pectin has broken down, so a glut of soft strawberries is the hardest possible jam. It is a fine reason to make a fruit syrup or freeze the fruit for a crumble instead.
Questions people ask
Can I test how much pectin fruit has?
There is an old methylated spirits test — a teaspoon of cooked fruit juice dropped into a tablespoon of meths, which clots into a firm lump if the pectin is high and into stringy wisps if it is low. It works, but it is fiddly and the meths must be thrown away, so most people just use the fruit lists and rely on the saucer test.
Is jam sugar worth the extra cost?
For low-pectin fruit, yes — it removes the main failure mode for a small premium and it is far cheaper than a wasted batch. For apples, currants or damsons it is money wasted, and it can give a slightly rubbery set on fruit that had plenty of pectin already.