Making blackberry jam

Plump blackberries

I found a couple of fantastic spots for blackberry picking this year – both within a 30 second walk of my house! The blackberries ripened early so I’ve been storing them in the freezer ready for making jam and fruit crumble. I managed to pick 7lb of fruit and there was still plenty left for wildlife – I must be the only person picking from these spots!

After picking the fruits, I washed them, let them dry on kitchen roll and put them in a sealed plastic box in the freezer. I wasn’t sure if using frozen rather than fresh fruit would affect the taste, but the blackberries were defrosted before use and made seriously delicious jam – so much so that I am not going to buy any more shop bought jam.

Pots of frozen blackberries

Key equipment

  • Maslin / jam making pan – make sure you check that the pan you are buying is suitable for the heat source e.g. induction hob, gas hob. I bought a 9 litre pan which is pretty huge but I had no problems with overflow when it reached a rolling boil so I’m glad I bought a big size. I can also make mulled wine in it at Christmas!
  • Jam funnel – I didn’t buy a jam funnel because I (naively) thought I’d be able to spoon the jam into the jars. Luckily my friend had bought a jam making funnel. Without it, more jam would have ended up on the outside of the jar.
  • Stainless steel utensils.
  • A cold plate for testing setting point.

Both delicious!

Decagon jam jars

I found some beautiful vintage style jars at Wares of Knutsford. Even though I left my jar order a little late and it was peak jam making season, I received my order within 2 days by courier.

What type of sugar for jam making?

I was umming and aahing about whether to use jam sugar or regular granulated sugar. I decided to go down the traditional route and use normal granulated sugar and a lemon (acid helps preserve) and it worked perfectly. Jam sugar is unnecessary – unless you can’t get hold of a lemon.

Chopped apples and blackberries

Chopped apples and blackberries in the maslin pan

Bringing the jam to a rolling boil (meaning it does not stop boiling when stirred).

Bubbling, colourful jam

Very hot blackberries and apples – starting to look more jam like!

Smooth jam consistency

The jam has reached setting point (put small amount on a cold plate, refrigerate for 2 mins, ready when it wrinkles) and is ready to be put into jars using the jam funnel. I didn’t get any photos of the setting point as everything got a bit hectic!

Messy jam funnel in jar

The jam has been put into hot jars and sealed. It’s now ready to cool and then label.

Jars with post-it note labels

Nom! Now all I need to do is make some labels for Christmas.

Jar of blackberry jam and toast

Jam making tips

  • Use your left over lemon to rub the cooked jam off the pan, it saves alot of scrubbing!
  • Have two plates in the fridge for testing the setting point so you don’t have to worry about cleaning the plate when timing the set.
  • Clean the jar top after pouring in the jam and seal as tightly as you can.

5 Comments

  1. Angela Hickman

    Hi Gemma
    By accident I came across your blog from September 2012 about blackberry jam and was delighted that you felt that jam sugar is unnecessary. I am a WI preserves judge and increasingly so exhibitors are turning to jam sugar in the mistaken belief that it is a necessity for jam.
    High pectin fruits do not need the addition of extra pectin. In this category I would include apples, black and red currants, gooseberries, damsons and quinces to name a few. Although commercial pectin and jam sugar contain natural apple pectin, they also contain preservatives and stabilisers which can affect flavour and, in large concentrations can be carcinogenic. When making jam from low pectin fruits like strawberries, cherries, pears and figs, the addition of a homemade pectin stock made from apples, red currants or green gooseberries can avoid the unnecessary use of jam sugar. If time does not allow the preparation of a stock, then substitute some of the granulated sugar with jam sugar but not completely.
    As a preserves judge, the gel qualities and consistency of jams and jellies made with jam sugar is altered. They almost have a rubbery consistency and in particular with strawberry jam, the fruit often floats to the top of the jar with a jelly in the bottom half. Granted the colour may be more vibrant due to a slightly shorter boiling time but this is another sign that jam sugar has been used.
    Just one little correction to your blog. Lemon juice does not contain pectin. To obtain a good gelled set, you need the correct ratio of pectin, sugar and acid. Lemon juice is added to strawberry jam to increase acidity as they do not contain much acid. Blackberries which were the subject of your blog, contain medium pectin when slightly underripe and very little when ripe. They are also low in acid so it is necessary to add a little lemon juice to increase acidity. If you only have ripe blackberries then the addition of some green apples (Bramleys are excellent) will boost both pectin and acidity.
    If you are keen on preserving it is worth doing a pectin test on the simmered fruit before the sugar is added. This can take the guess work out of whether there is enough pectin to achieve a good set. Forgive me if you already know how to perform a pectin test. However if not, take a teaspoon of your simmered fruit liquid before adding sugar and place in a small white cup or ramekin. Add three teaspoonsful or a tablespoon of methylated spirits and swirl together. Stand for a minute. If a one piece clot of gunk is formed the there is enough pectin. If it breaks into several pieces then there is not and you need to simmer a little longer to reduce the liquid and increase the pectin concentration.
    An excellent reference book for preserving is the tried and tested ARFC Institute of Food Research’s “Home Preservation of Fruit and Vegetables” 1989
    ISBN 0-11-242864-9. these recipes if adhered to will never fail you. Alternatively, Vivien Lloyd’s “First Preserves” is a modern, well illustrated guide for both beginner and experienced preserver. Many of her recipes are scaled down from ARFC ‘s publication.
    Hope you find my comments of some use and keep up,the home preserving. It is very rewarding. I have a professional career and the judging and preserving is a very therapeutic form of relaxation for me.
    Happy jamming!
    Best regards,
    Angela Hickman

  2. Ah, blackberry jam, I grow some cultivated, thorn less blackberries and they produce large berries. I am interested in your comments about not using jam sugar – point taken. I put some apples into the jam and that sets it quite well. Question what will be the result if I put the jam through a sieve to remove a lot of the pips and cores before bottling? Would this make a Jelly type jam or whatever? I prefer a jelly type jam from berries as the seeds play havoc with dentures, interested in your comments. Regards

    • Hi Brian. I often add a few chunks of apple too just to make sure I get a good set. I’ve put this jam through a sieve and it’s lovely, really velvety and sweet! Just a little past soft set is a nice consistency but if you prefer something firmer cook it for a little longer and it will more like a loose jelly. If I have enough time I normally sieve any jam containing lots of seeds as it’s a little easier to eat. You normally lose around a third of the volume and it takes time but it’s worth it. I sometimes add a few raspberries in there too. Tastes fantastic. Let me know how you get on!

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