Food Preservation: Jam

We’ve used blackberries for this post but the process is the same whether it’s blackberries, strawberries, raspberries, or many others. It’s basically the recipe that we made, with and some additional information thrown in ūüôā



  • 2 1/2 lb (1 1/4 kg) of berries
  • 1 1/2 cups of sugar
  • 1 lemon or lime


Note: If you want to keep the seeds in your jam you can skip step 3 and the mashing part of step 2.

  1. Combine the sugar and berries (if you have time, leave them to macerate overnight)
  2. Soften the berries over a low/medium heat (you can use a potato masher to start getting the juice out as much as possible).
  3. Pass the berries through a sieve, pushing through as much of the pulp as possible.
    Meanwhile: put a large pot of water on to boil (big enough to submerge your jars in).
  4. Add the juice of a lime or half a lemon
  5. Cook the resulting liquid, slowly bringing it up to bubbling point.
    Meanwhile: place your jars in the large pot of water on to boil.
  6. When your liquid/pulp has thickened begin testing (see below)
  7. Once desired consistency has been reached, remove from heat.
    Meanwhile: remove jars from boiling water.
  8. Immediately pour your hot jam into your hot jars.
  9. Water process if required (see below).

Testing for consistency


Very simple: put a couple of saucers in the freezer while you’re cooking your jam/chutney. When you suspect your product may be ready drop a small amount on a cold saucer. Allow to cool for a minute, then tip the saucer to see if it runs, and pull your finger through the middle to see if the path remains clear or if the contents refill the gap. If your product is not setting well yet, return the saucer to the freezer and repeat at intervals till the desired consistency is reached.

Water bath processing (canning)


This is done as soon as the jam is in the jar, while it’s still hot, in order to ‘can’ the product. Essentially, you fill your hot sterilised jars with a hot product, seal, and boil¬†the filled jars for the required time (according to the recipe you’re following). The hot product is pasteurised¬†during cooking to avoid botulism and as the jars cool a vacuum seal is created which avoids oxidation. This results in a product that can be stored at room temperature rather than in the fridge, and it will last much longer. Water bath processing is not necessary if you’re putting your product straight in the fridge for immediate use.


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