Jam makers over here please! Couple of questions...

[Lexilicious]

This morning I am doing apple and elderberry jam. I have a crate of bramleys from my parents' trees, and elderberries from foraging near here. I got a hot tip recently to use the skins and cores from apples tied up in a muslin to get more pectin out, which I'm going to do. Question is, do I measure out the sugar in relation to the apple flesh weight or the flesh and cores weight (i.e. whole apple before chopping)?

Also, anyone have a foolproof way of calculating how many jars it's going to fill? I am always discombobulated by adding weights of fruit, water, sugar and then they come out at something completely different when it comes to jarring-up time.

Apples only have pectin in them before they are ripe...but there is usually enough in them to set most apple jams/jelllies.

I use the same weight of sugar to weight of 'stuff' going into the final jam/jelly.

I do my jarring by eye. I have no idea how to gauge jar numbers apart from by eye.

Calculate using flesh only weight. The cores, pips etc will be taken out at the end of cooking.

I think it's difficult/impossible to calculate number of pots precisely because the water content and pectin in each new batch of fruit varies so much. So you end up having to boil off different amounts of water. For example, one amazing year I boiled some apple and elderberry for 12 mins and had the most perfect jelly set. But that was flukey. In general, I find elderberry jelly really difficult to get a set. Oh, if you're making jelly, you use the strained liquid volume to calculate sugar quantity. Just in case.

Fab advice thank you. I will report back...

Ok done. Kept the muslin with the skins and cores in until just after the sugar went in. I was going to leave it longer but then realised it might be soaking up the sugar. I suppose I shouldn't have had it in there at all once the sugar was in. Anyway, I let the bag drip on a plate and also squeezed out as much liquid as possible once it was cool enough.

So it was 2kg fruit, 5 parts apple to 3 parts elderberry, 2kg sugar. Has end up very rich dark colour. Nine jars of various small-medium sizes. Had a little bit on toast already, although not yet set. YUM!

Hmm, I don't think they have set. I used a jam thermometer, it was definitely boiling at jam temperature for more than ten mins. I guess the only thing to do is re-boil, with a bit of lemon juice added?

Or scrub out 'jam' on the labels and write 'conserve' ...?

Apple drizzle jelly...

You have to test the set. Just going by time/temp isn't foolproof as you've found. Stick a couple of saucers in the fridge before you start, then when you think it's ready, drop a blob on a cold saucer. After a few seconds draw your finger over the top - if it wrinkles and clumps it's set. If not, keep going.

*disclaimer I usually make jelly rather than jam so it's smooth, but the principle is the same I think.

Yes, a wee tip for next time is to stick a blob on a teaspoon and leave it in the fridge or iver an ice cube for a few minutes. if the top puckers when you prod it it's ready, you can't rely on temperatures or boiling times.

i don't even have a thermometer i just wing it and test it this way.

also, if you are making jam using low-pectin fruits it sometimes helps to use Preserving sugar as it has added pectin.

I buy jam sugar and use about half jam sugar to half normal for most fruits. Not plums though. That ends up as plum Tarmac if you put any more pectin into it! But for pretty much everything else it is more or less foolproof.

If I am unsure that jam is going to set I sometimes leave it overnight in the saucepan. If it has set by the morning I know it's OK and boil it up again and then pot it.