If you enjoy building and making electronics, chances are you’ll get a buzz out of making jam and it really is very simple. This example uses blackberries and strawberries – the former because they’re abundant in the hedgerows at the moment, the latter because I had a bumper crop this year and froze them. Frozen fruit works absolutely fine for jam making – just make sure to thoroughly defrost it (don’t worry if it goes mushy).
To make 2KG jam you’ll need:
- 1kg blackberries/strawberries (I used a 75%/25% mix because I had more blackberries)
- 1kg bog standard white sugar (NOT jam sugar)
- Half a lemon
- 50ml liquid pectin – Certo is the best, you can get it in Tesco
- Jam jars – I used a mixture of 125ml Kilner jars I bought at Wilkinsons for £1 each and empty preserve jars
- Saucepan
- Recommended: jam thermometer, jam funnel
To clean the jam jars, run the glassware through a dishwasher cycle, allow them to dry and, when you’re ready to make the jam, stick them in a cold oven and then turn the heat on. Heat them up to 200C and then turn the oven off, leaving the door shut. To sterilize the tops, pop them in a bowl and pour boiling water on them
- Remove any husks and thoroughly wash the fruit
- Bung the fruit in a large saucepan – if in doubt go for the biggest one you have. A stock pan or the bottom part of a large steamer will do. Pour on the juice of half a lemon.
- Place on the hob over a medium heat and warm the mixture, stirring regularly, for 20 minutes or so – until the fruit is cooked and at the right consistency. I use a potato masher to give it a little “encouragement”
- Now add the sugar and stir till it dissolves – this can take 5 minutes or so, be patient
- I recommend using a jam thermometer as it takes the guesswork out of the next stage. Turn up the heat until you achieve a “rolling boil” which happens at 105C. Leave it there for 1 minute then remove from the heat
- Get the jam jars out of the oven.
- Leave it for 5 minutes to cool a little, then tip in the pectin.
- Bring it back to a rolling boil (105C), stirring constantly (be careful of spitting jam!) and hold it there for a minute then take it off the heat
- Test for “setting” by plopping a teaspoon of mixture on a cold plate. Let it cool for a few seconds then push it with your finger. If it wrinkles at all, it’s ready. If not, repeat steps 8 and 9 until it does (it usually works first time)
- Carefully pour the hot mixture into each jam jar using the funnel – filling to the bottom of the neck. As soon as you’ve done that, use an oven glove or tea towel to very carefully hold each jar as you screw the lid on tight. As the jam cools, the air will contract, pulling the “safety button” on the top of the lid inwards so you’ll know if it’s properly sealed.
- Leave to cool naturally.
That’s it! You can feast on the odds and ends immediately but the sealed jars will keep for around a year. Once opened, they’ll last around 8 weeks in the fridge.
If you’re making jam with fruit that has a skin (plums and apples, for example), you may not need to add pectin at all (pectin is made from apple skins). In that case, test for a “set” after step 5 and only add the pectin if it won’t set on its own. In my view, it’s better to have too much pectin (and, therefore, a firm jam) than too little.