How To make jam

This recipe is for strawberry jam, which can be harder to make due to the low pectin content in strawberries, but master this and you can make any jam. Pectin is a natural gelling agent, which is present – in varying degrees – in all ripe fruit. Because strawberries are low in pectin, it’s best to use a jam sugar, which has added pectin. (Don’t confuse this with preserving sugar, which has no added pectin.)

The addition of lemon juice is to help the jam set, as it’s another high-pectin fruit. Avoid washing strawberries as they absorb water, which will dilute the pectin and make setting difficult. If you must wash them, dry thoroughly with kitchen paper. Hull the fruit, halve any large ones and remember strawberry jam will have a soft set.

1. To make 3 x 500ml jars of strawberry jam, you will need 1.1kg fresh strawberries (slightly under-ripe is better than over-ripe), 1.1kg jam-making sugar and the juice of 1 large lemon. Also, a preserving pan, jam funnel, large ladle, 3 or 4 small plates, a wooden spoon, 3 x 500ml Kilner jars, or 6 x 250ml jam jars, plus wax discs and Cellophane. Pop the plates in the freezer, so they are chilled and ready to test the jam later.

2. Put the strawberries into the preserving pan with the sugar and the lemon juice. Put over a low heat and warm through until the sugar dissolves. You can shake the pan every now and then, but avoid stirring as you may break up the fruit too much. Be patient: don’t be tempted to turn up the heat or you will burn the sugar. Let it slowly dissolve with the juices from the fruit.

4. Take 1 of the cold plates from the freezer. Spoon a little of the jam onto it and pop back into the freezer for 1 minute to cool. Remove the plate from the freezer and run your finger through the cold jam – if it wrinkles, it’s set. If not, return the jam to the boil for a further 1-2 minutes and repeat this process. You may need to repeat this a few times until the required set is reached. Use a new cold plate for each pectin test.

5. Next, take a dessertspoon and skim off as much of the scum (or white froth) as you can. Then leave the jam to sit for about 15 minutes before potting it. This prevents the fruit from floating to the top of the jam.

6. Use the jam funnel to ladle the jam into sterilised jars. Do not overfill. Cover and close the clips. (If you are using jam jars, put the wax discs on while the jam is hot to melt the wax and seal in the jam, then cover with Cellophane). Cool, then label the jars.

Pick your own flavour

Both raspberries and blackberries have a slightly higher pectin content than strawberries, but it’s best to use jam-making sugar to ensure a good set. If you prefer to make a jam with these berries, simply follow the recipe featured.

Preheat the oven to 120°C/fan100°C/ gas 1/2. Wash the jars in warm, clean soapy water, then rinse in clean water. Put upside down on a clean baking tray and put into the oven for 10 minutes to dry out. Use a clean cloth to handle the jars.