Acid without pectin
Rhubarb is one of the sharpest things in the garden, so the acid half of a set is amply supplied and no lemon juice is needed for that purpose. What it does not have is pectin, and without pectin there is nothing to build the gel from.
Jam sugar solves it outright. So does a grated cooking apple, or the juice of a couple of redcurrants' worth of high-pectin fruit, or commercial pectin added at the end.
A lemon is still often added, but for flavour and for a little extra pectin from the pith rather than for acidity.
The method
Macerating first is what keeps some texture.
- Trim the rhubarb and cut it into short lengths — two or three centimetres. Do not peel it; the skin holds the colour.
- Layer it in a bowl with sugar, roughly three-quarters of the fruit's weight, and leave it overnight. A great deal of juice comes out and the pieces firm up.
- Tip everything into a preserving pan. Lift the rhubarb out with a slotted spoon and set it aside.
- Boil the syrup on its own for ten minutes until it thickens noticeably. Put two plates in the freezer.
- Return the rhubarb, add jam sugar or pectin according to the packet, and bring back to a rolling boil.
- Boil for five to eight minutes only. Rhubarb disintegrates fast and this is where the texture is lost.
- Test on a cold plate, skim, stand for ten minutes and pot.
Pairings
Rhubarb is sharp and slightly one-dimensional on its own, and it takes to partners better than almost any fruit.
- Rhubarb and ginger, which is the classic and hard to improve on. Use both fresh and stem ginger.
- Rhubarb and vanilla, with a split pod in the pan.
- Rhubarb and orange, using zest.
- Rhubarb and strawberry, where the strawberry adds sweetness and the rhubarb adds the acid it lacks.
- Rhubarb and rose, which is delicate and unusual.
- Rhubarb and star anise, which suits it surprisingly well.
- Rhubarb and elderflower, at the very end of the forced season.
Notes
- Forced rhubarb
- Pink, slender, tender, mild. January to March, and the one for colour.
- Maincrop rhubarb
- Greener, thicker, more strongly flavoured. Better taste, duller jam.
- Do not peel
- The colour is in the skin.
- The leaves
- Rhubarb leaves are not eaten. Discard them — a food-safety matter for the Food Standards Agency.
- Texture
- Rhubarb collapses very quickly. Macerating first and boiling briefly is the only way to keep pieces.
Forced and field rhubarb
Two quite different ingredients sold under one name, and which you have changes the colour, the cooking time and the flavour.
- Forced rhubarb
- Grown in the dark in heated sheds, harvested by candlelight, in season roughly January to March. Pale pink, thin, tender, delicate.
- Field rhubarb
- Grown outdoors, from about April into summer. Thicker, greener, firmer, more astringent and much more strongly flavoured.
- For colour
- Forced, every time. Field rhubarb makes a khaki-brown jam however it is treated.
- For flavour
- Field rhubarb is the stronger and arguably the better, and it wants more sugar.
- Cooking time
- Forced collapses in minutes; field takes noticeably longer and holds its shape better.
- Improving the colour
- A little grated beetroot, hibiscus, or a few raspberries added to field rhubarb. Cosmetic rather than dishonest.
- The leaves
- Never eaten, in any quantity or preparation. They are not food.
Common questions
Why will my rhubarb jam not set?
Rhubarb has almost no pectin. Use jam sugar, add pectin, or include a grated cooking apple.
Do I need lemon juice?
Not for acidity — rhubarb has plenty. A lemon adds a little pectin and some flavour.
How do I stop it going to threads?
Macerate it in sugar overnight, boil the syrup separately, and give the fruit only a few minutes at the end.
Should I peel it?
No. The skin carries the colour.
Which rhubarb?
Forced for a pink jam, maincrop for a stronger flavour.
Try this next
- Rhubarb forced and maincrop
- How to make jam the setting principles
- Ginger the classic partner
- How to make rhubarb cordial the other use for a glut