I tried grabbing them as and when they were ripe and piling them into a bowl in the kitchen, waiting to have enough to do something with... but trust me, you're glad I haven't included a photo of what happened there. Suffice it to say they were fit only for compost by a couple of days later. Thankfully I quickly hit upon a better plan, giving them a quick rinse and then popping them into a box in the freezer. You can cook with blackberries straight from frozen.
I haven't made jam before, so I had to do a bit of research before heading to the kitchen. An even ratio of fruit to sugar (by weight) seems to be a fairly universal recommendation, and has the advantage of being easy to remember.
Blackberries don't contain much natural pectin, so I added a small amount of apple to help the jam to set firm. Of course, you could use pectin-enhanced sugar instead, or just settle for a slightly runnier consistency. This one set really well, though, and the apple pieces are so small that you don't notice them after cooking.
This is a really easy recipe, perfect for your first foray into jam-making. Mine was in the jars within 30 minutes of weighing the ingredients. And even a sugar thermometer isn't essential, as you can easily test the consistency using a cold plate (and you'd want to do that anyway, as it's the best way to see what's really going on).
Blackberry & Vanilla Jam
Makes enough to fill 2 jars (450g/1lb size)
450g (1lb) blackberries
120ml (½cup) water
2tbsp lemon juice
1/4 of a large cooking apple (approx. 50g/2oz)
450g (1lb) granulated sugar
2 vanilla pods
- Sterilise your jam jars, for example by part-filling clean jars with water and standing them in a pan of boiling water for a few minutes. (There are many other methods.)
- Put a small plate in the freezer.
- Wash the blackberries and put into a heavy-bottomed pan with the water and lemon juice.
- Grate the apple into the pan.
- Bring to the boil over a medium heat, and simmer for 5 minutes.
- Add the sugar, stirring gradually until all the grains have dissolved.
- Scrape the seeds from the vanilla pods into the jam, and stir.
- Increase the heat and boil vigorously for about 20 minutes, or until a sugar thermometer consistently reads 104°C (220°F).
- To check whether the jam is setting, retrieve your plate from the freezer, and drop a little jam onto it. The cold of the plate should cause it to set quickly, so that if you push the edge of the drop with your finger, it will react like a jelly instead of a liquid. If not, continue to boil for a couple more minutes, then test again.
- Decant the jam into the jars, and top with a piece of greaseproof paper. Screw the lids onto the jars while the jam is still hot, to form an airtight seal.