Without pectin, there is no jam, but how do you work out whether you need to add it? Ready my guide to pectin for jam makers to learn how to do a pectin test, how and when to use pectin powder, and everything you need to know to get a perfect set.
The basic science of jam
Successful jam making requires three things: pectin, sugar and acid. Pectin is what makes jam jammy! Without pectin, jam would be just thick, but runny and unset fruit syrup. But what is it?
Pectins are long chain sugar molecules that help bind the cells of the fruit together. By boiling the syrup, pectins in the cell walls are released and then bind to each other. It is this reaction that gives jam its jelly structure.
For jam to set, there needs to be enough pectin. If you don’t have enough in the fruit, you need to add more. Otherwise, no matter how much you boil the jam, it will never set. You will just be left with a thick, sweet fruity syrup.
Pectin levels in fruit
Some fruits are naturally high in pectin, some low. Generally the riper the fruit the lower the amount of pectin and vice versa, so if you are using very ripe blackberries, that might push them from the mid pectin category to low pectin.
There are plenty of tables available to check which fruits are likely need extra pectin, and you will find a quick reference list below.
If you have a type of fruit that isn’t on any of the lists, though, don’t despair. It’s easy to test how much pectin is in your fruit, so you will always know if you need to add some more.
It is worth remembering that the amount of pectin in one type of fruit can vary a lot with ripeness, variety and even growing conditions in a particular year. For example, one study* found that the level of pectin in apricots varied from 0.4% to 1.3%.
Because of this, you may want to check your fruit for pectin, even if you know that you have fruit that is typically high or low in pectin.
Low pectin fruit
Medium pectin fruit
Medium high pectin fruit
- Cooking apples
High pectin fruit
- Crab apples
How to test for pectin
First, cook the fruit you are going to use in your jam. Do this without adding all the sugar and bringing it up to the boil – the first stage of a traditional jam recipe.
If you are planning to use a conserve method that involves macerating the fruit in sugar, you will need to take a very small bit of fruit and cook it to test.
Take a teaspoonful of juice from the cooked fruit and put it in a small glass or dish. Allow to cool for a minute or so.
Now add 1 tablespoon of methylated spirits. That’s a ratio of 3 parts methylated spirits to 1 part fruit, by volume. Swirl the glass to mix the contents and then allow to stand for a minute.
You can expect to see one of the following results:
If the mixture forms into a single jellified lump, there is a high level of pectin in the fruit.
A squashier, more amoeba-like results means medium pectin.
Small blobby pieces floating in liquid means low pectin.
If the result indicates low pectin levels, but you are using what is usually a high pectin fruit, then you can try simmering the fruit for about 5 minutes and then test again. It may be that some extra cooking time will release more pectin from the fruit.
Once you know the pectin content of the fruit, you can decide whether you need to add some more for a reliable set. Use either liquid or powdered pectin, or jam sugar that has powdered pectin added.
How to add pectin
Pectin is available as a liquid, as a powder or added to jam and preserving sugar.
Pectin powder is easy to use, as you just follow the instructions on the packet. This normally involves adding pectin at the same time as the sugar.
The other way is to use a jam sugar that already has pectin mixed in. Check the ingredients just to make sure that it does contain pectin!
Jam sugar should contain added pectin. Preserving sugar, on the other hand, is just sugar with larger crystals that is particularly suited to making jam with pectin-rich fruit. Be careful not to confuse the two.
Don’t add pectin if it’s not needed, though. This can result in a jam or jelly that’s far too rubbery and disappointing.
How to Test for Pectin
- 1 tsp cooked fruit
- 1 tbsp methylated spirits (denatured alcohol)
- Place the teaspoon of cooked fruit in a small glass or cup. Allow to cool.
- Add the methylated spirits and stir briefly or swirl the glass to mix the contents.
- Allow to stand.
- If a jellyfied mass forms, the fruit is high in pectin. Small floating blobs indicates low pectin, and you should consider using jam sugar or adding pectin powder to achieve a good set.
*Campbell, L.A. and Palmer, G.H. 1978. Pectin. Ch. 4, in Topics in Dietary Fiber Research, G.A. Spiller and R.J. Amen (Ed.), p. 105–115)
For more detailed information, “Reassessment of Some Fruit and Vegetable Pectin Levels by Robert A Baker” is a good starting point. It can be found here.