We went blackberry picking on Saturday as we are fortunate enough to have quite a few areas of unspoiled (ie not near a road) blackberry bushes around here.

After making several batches of blackberry jam (my preserving pan is very old and has been inherited and can only cope with 1kg of fruit - slightly annoying), I had 450g of blackberries left over. I was about to freeze them as I wouldn't have had enough to make a whole 2lb jar and the only small jar I had left would have been too small and then I remembered the punnet of blueberries I had in my fridge so thought that I would combine the two fruits and try out a black and blue jam.

The recipe is simple and to be honest I think I hit on the right balance of the fruit straight away - 60% blackberry and 40% blueberry but you are more than welcome to try another combination and see how that turns out.

The jam is a beautiful, glossy dark purple colour. It looks really sumptuous and is very moreish (hence why there isn't much left!). It is sweet and yet it has bite from the blackberries which is balanced with the blueberries which add a real smoothness to the taste. I like to keep as much of the fruit bits as I can in my jam but you can strain it if you are not a fan of blackberry pips. But the fruit gives it a lovely texture that makes it look even more yummy on crumpets and bread. I was also really pleased that there was no cloyiness after you finished it. It was just nice and clean and made you want more!

I use Tate & Lyle's Jam sugar (£1.08 for a kg bag from Sainsbury) so that I don't need to worry about adding pectin etc. It's just all in the sugar and you use the same weight of sugar to fruit - how simple is that!

So for this batch of jam I used
450g of blackberries (washed with all stalks, leaf debris etc removed)
300g of blueberries (washed with all stalks removed)
the juice of one good size lemon (ensure no pips get in the mix)
750g of jam sugar.

Method:

- Heat the blackberries, blueberries and squeezed lemon juice in your preserving pan or heavy based saucepan for a couple of minutes until the fruit starts to break down slightly and release its juice.
- Add the jam sugar and mix/stir until dissolved and then let it boil at a rolling boil for 6 minutes or until the setting point is reached. If you have a confectionary/sugar thermometer you should look out for 105 degree centigrade. According to my Mum's jam making recipes this is the usual setting point but it is always wise to check. One thing I always do to check setting point is put a couple of saucers into the freezer for a few minutes before I start making the jam and when I am ready to test take one out, take the jam off the heat and place a teaspoon of the mixture onto the cold saucer. if it immediately sets and when you push it with your finger the surface crinkles then it has reached its setting point. If it is still a little too runny then put it back on the heat boil for a little longer testing at 1 minute intervals (hence why you need 2 saucers in the freezer just in case!)
- Once setting point is achieved you allow it to stand for 15 minutes and then you can skim off any scum from the surface before jarring up.

Your jars must be sterilized. I always do this by
- washing the jars (usually old jars that I buy honey, olives, pickles in etc) in very hot soapy water and then rinsing in hot water
- pouring freshly boiled water into them and allowing them to stand. -- Just before I start making the jam I turn the oven on to 200 degrees centigrade (depending on how long it takes your oven to heat up you may need to do this earlier) and by the time the jam has finished cooking the temperature is reached. Then using tongs I tip the water out of the jars and pop them onto an ovenproof tray and put into the oven for 10 minutes.
- I boil the lids for 15 minutes in a pan of water.
-Always remember to handle the hot jars with tongs or oven gloves.

I always time it so that I take the jars out just after I have skimmed the jam and then I am ready to pour the jam in. I use a funnel to ensure no mess gets around the side of the jars and it is far quicker as you just ladle it in. Fill the jar to 1/2 a centimetre below the jar neck and place a wax disc onto the jam immediately. Once they are almost cool I wet the cellophane discs and place them over the jar top and secure with an elastic band. As that dries it forms a really tight seal and then I screw the lid on. As long as the seal is not broken you can keep the jam for up to 6 months and or 3 weeks in the fridge once opened.

I made approx 950g of jam in the batch and all it cost me was the blueberries which were on offer in Sainsburys and were £1.49 (but can be as much as £3.99), a lemon - £0.16 and £0.81 for the sugar (750g of a 1kg bag) - a grand total of £2.46 (£1.17 per 454g). It isn't really any cheaper than buying the jam but it is so much nicer.

If you are looking for something slightly different I can really recommend my little experiment of a jam.