A painstakingly good preserve: Strawberry Jam

I love Strawberry jam. Strawberries are a classic flavour of the British summer, and with their vibrant colour and their fresh juicy fragrance, and their heart shape which encapsulates the joy that these tiny gems bring, who can’t resist this wonderful little fruit? It just cries out to be put in a preserve so it can be enjoyed year round.

And yet, ask any jam maker, it is one of the hardest jams to make. This is simply because of its low pectin levels. Pectin is a chemical found in all fruits and it’s essential to get a good set for jams. Fruits with low pectin need a helping hand.

You can actually test the pectin level of your fruit to gauge the amount of help you’ll need to get a set. The test involves adding a bit of fruit to methylated spirit and seeing if it gels. I don’t really do this as I don’t like messing with chemicals in the kitchen but if you fancy a little science experiment then this might be worth a try!

For low pectin fruits you can add pectin yourself, more on this below. Incidentally jam sugar is just normal sugar with powdered pectin added and finished off with a doubling of the price tag. You can buy your own pectin and add it yourself and save a fair few pennies.

Lemon juice is another helping hand. Lemon juice helps the pectin to get to work. It lowers the pH level of the fruit and sugar mixture that is the starting block to any good jam, and thereby helps the pectin molecules to bind and set the jam.

Finally you need a lot of patience. All fruits vary in their natural pectin content, and even two batches of the same fruit will not be the same. As we are dealing with natural ingredients each batch will be different. Some fruits you just know roughly how long to cook the fruit and you know it will have set. With strawberries there is less certainty, and lots of constant checking until you get to setting point.

Strawberry jam recipe



Granulated sugar and pectin or Jam Sugar

Lemon juice

Spices if desired

Note that this list doesn’t have weights. See method for how to work out weights for your jam


  1. Put a ceramic dish in the freezer to test set later. Wash your jars you will be filling with jam and sterilise.
  2. Weigh your strawberries and note down the weight. Hull them removing all leaves and then chop to your desired size (ie depending on how chunky you like the fruit in your jam, or not). Add to a heavy based tall pan.
  3. You can add some spices if you want at this point. Vanilla, cardamom and a mix of spices all work well. Use 2 teaspoons of spice per kilo of fruit. You can of course skip this bit.
  4. Weigh in a bowl sugar that will equal about 75% of the weight of your fruit. So for 1kg of fruit, use 750g sugar. (Traditional recipes would say use 1 kilo of sugar per kilo of fruit, but I like to use less.) If you are using jam sugar then put this weighed sugar aside. If you are using normal sugar add about 10g of powdered pectin per kilo of fruit (I use the ‘Special Ingredients’ brand). Mix the pectin into the sugar and put aside.
  5. Cook the strawberries on a low heat until soft. You don’t need to add any water if you keep the heat really low at first, because the strawberries will release a lot of liquid themselves.
  6. Add the sugar and stir until dissolved. This will be when there are no more sugar crystals. Once dissolved, add the lemon juice. Start off with 150ml lemon juice per kilo of fruit.
  7. Increase the heat and bring to a rolling boil, ie when the jam is boiling and it looks like there’s lots of bubbles. Boil for 8 minutes.
  8. Test for set by dropping a small amount into your dish you placed in the freezer earlier. Leave for a minute then push the jam forward on the plate with a finger. If a crease forms on the skin the jam is set. If not, keep boiling and testing for set every 2-3 minutes. If after 2 or 3 tests the jam is not setting add a couple more tablespoons of lemon juice and keep boiling.
  9. Once you have a set, turn off the heat and leave the jam for about 10 minutes before filling your sterilised jars, to allow the fruit to settle evenly. Remove the scum from the top with a sterilised spoon until the surface is clear. Jars should be ideally warm when filled and covered with lids or cellophane immediately. Properly sealed jars prepared in this way should last 12 months or even more.