Help - Plum Jam not set !

[Susiebelle]

I set about making three batches of plum jam yesterday, even cracking open the stones and using the kernals (now that's a labour of love)  anyway19 jars in all, I batch of 5 jars will be just OK as I don't like a firm set, but the others are a lovely colour but look more like fruit puree!
I don't like my jams over sweet or well set, and although I make jam every year this is the first time I have made plum jam, I used preserving sugar.
Can anyone advise on the best way of correcting this without ruining the flavour, I have thought of boiling back up with redcurrant juice or adding more sugar and apple juice, has anyone any thoughts please.

[PurpleHeather]

My mother who always made loads of jam which some times did not set, used to empty the lot back into the pan and reboil it. She always lost liquid to equal a pot of jam when doing it, but it always set.

I always collect citrus pips (lemon lime grapefruit or orange) in a  tiny tub in the freezer. Then when I need jelly I boil a table spoon full of these in a half a pint of water for several minutes, the natural pectin in the pips turns to a jelly and strain and throw away the pips add the jelly to the unset jam and recook it will make it soft set.

You can artificially thicken for family use with things like arrowroot, even cornflour,  but it wont 'keep' as long as proper jam, gelatin adding can be done if you are not offended by using it but again it wont keep long. Using less sugar and gelatin is often favoured in small batches by those who need a low sugar diet but of course it technically can not be called a proper preserve.

I did try using the kernals myself in a batch of jam but the recipe did say not to use them all because the outside of the stone is needed to give off the setting agent. Only crack open half.

If memory serves me right  from reading up on it .  The inside of the stone contains a poison, so you either have to use the full stone or the kernel. you can't get the kernal out then use the opened nut shell part. Or it can make you very ill or worse.

[Susiebelle]

Thank you  PurpleHeather, a lot of information and  will certainly print off and keep for the next batch.
The recipe I used told me  to discard the stones after cracking half open to gain access to the kernels, i.e. not to cook the stones with the plums there I think is my problem!

Once again many thanks

[PurpleHeather]

My pleasure.

Yes it was short on detail.

Use half for the almond flavour kernal and cook half for the setting.

Next tip......count the stones in and out so that you know how many to remove before you put the jam into jars.

Horrible, finding a fruit stone in a gob full of jam.

We are all still continually learning.....Please share your knowledge.....Freely.

[Susiebelle]

I will when I have enough - though I feel there's a  long way to go, many thanks!

[Trevor_D]

I always take the stones out before I start. (And I use ordinary granulated, not preserving.)

I make plum jam every year and I've never had any problems getting it to set - they've got plenty of pectin - until this year! Was it just me - as I thought - or - as you've had the same problem - is it the plums? I did read in one of my ancient cookery books that in a year when the fruit is good, the jam isn't. Something to do with the texture and lack of acidity. And this year has been brilliant for all fruit, and especially plums! Just a thought.

My answer was to tip it back and boil it up again. Worked a treat. (But I've ended up with less jam!)

[Susiebelle]

Thanks Trevor_D, that makes me feel a bit better, I thought I was losing the knack! anyway that's what I will do - whack it back in the pan and just boil it a bit longer.