Making jam is super rewarding (the jars look so beautiful) but it can be tricky if you have never made it before or no one has shown you how to do it. Here are a few tips I have found really useful.
Don’t try to make jam in really large quantities, even if you are a really experienced jam maker this can go wrong. Jam is best when it’s fresh, so if possible make in smaller quantities and freeze any excess fruit and then make more batches with frozen fruit as you need to. When making jam you want to boil the fruit for a short a time as possible to preserve the fresh flavour, if you make it is smaller quantities you will reach the setting point sooner so the jam tastes fresher.
Consider the amount of pectin in the fruit you are using. Pectin is a naturally occurring gelling agent that helps jam set. Lots of fruit has natural pectin but if you are using low pectin fruit (blueberries, strawberries, pears etc) you can add in pectin with other things – lemon juice, apples (or the apple peel and core and seeds in a muslin bag) or redcurrant juice – which is great for strawberry jam. You could also use preserving sugar which has added pectin which helps your jam set, but I find preserving sugar often gives quite a hard set for jam which I personally don’t like. If you do want to use preserving sugar consider using half and half.
You jam will set when it reaches 104C (presuming there is enough pectin). If you don’t have a jam/cooking thermometer you can check by putting a plate in the freezer before you start making jam. Then when you think the jam is set put a teaspoon of jam on the cold plate and put it back in the freezer for a couple of minutes. If a wrinkle forms on the surface of the jam when you gently push your finger into it then you know the jam is set.
Use warm sugar. This isn’t essential but by using warm sugar it will dissolve more quickly and it keeps the temperature of the jam higher so the jam should cook more quickly and have a fresher taste.
My jam-making master recipe is 700-900g sugar for every 1KG fruit. The amount of sugar depends on how sharp/sour the fruit is. For sharp fruits, like gooseberries, rhubarb or blackcurrants, add 90% sugar (or even a little more if very sour). For apples and pears (which are not very sour) I’d add a bit of lemon for extra acidity and then about 70% sugar. If your fruit isn’t very juicy you will also need to add a bit of water -see the Pear, Ginger & Rosemary Jam recipe below.
Probably the easiest and quickest jam to make. I make is all year round with raspberries we have frozen. Raspberries have enough natural pectin to set without needing to add anything else.
Makes 3 x 450g jars
1KG raspberries (fresh or frozen)
850g granulated sugar
Put the sugar in a heatproof bowl and put it in the oven at 140C for 15 minutes. This is a good time to sterilise your jars too! Put a plate in the freezer so you can check if your jam is set.
Put the raspberries in a large pan – it’s fine if they are still frozen. You will need a pan larger than you think as jam bubbles up lots as it cooks. I use a 9 Litre preserving pan – you could probably use something a bit smaller for this quantity.
Put the pan on the hob on a low-medium heat and cook for a few minutes until the juices in the raspberries start to run and the berries begin to break down a bit – this might take a bit longer if the raspberries are frozen.
Add the warm sugar to the pan and stir until all the sugar has dissolved. Then turn the heat up to high and cook for 8 minutes. Towards the end skim off any of the ‘scum’ that has risen to the top of the jam. Take the jam off the heat and test if the jam is set by using the ‘wrinkle test’ (see details above).
Alternatively, if you have a cooking thermometer your jam will set when it reaches 104C on the thermometer. Though I usually double check with the ‘wrinkle test’.
Pour into sterilised jars and seal.
Pear, Ginger & Rosemary Jam
Makes 5 x 450g jars
1.2KG pear (weigh once peeled & cored)
450g apples (weigh once peeled & cored)
2 lemons (juice only)
20g rosemary (weighed with stems, then finely chopped – about 1 tablespoon)
25g ginger, finely grated
1.2KG granulated sugar
Preheat the oven to 140°C. Put the sugar in a heatproof bowl and put it in the oven.
Put the chopped pear, apple, lemon juice, water, ginger and rosemary in a large preserving pan and bring up to the boil.
Reserve the apple peelings and cores and put them in a bit of muslin and tie them up. Put this in the pan with everything else. This is to add additional pectin. Allow to simmer over a medium heat for 15 minutes until the fruit is soft. Then fish out the bag of apple peelings, squeezing out any liquid back into the jam.
Add the warm sugar and stir to dissolve and then turn up the heat and bring to the boil. Boil until the temperature reaches 104°C or for 15 minutes and then check the jam for a set. Pot the jam up into sterilised jars.