experienced jam makers - advice please!

[whatalovelyday]

I'm new to jam. I made very successful strawberry jam earlier this summer using jam sugar. Made plum jam today using granulated as per recipe. It just didn't reach setting point. I think it's ok now but what should have made eight jars has boiled down to three. It still needs to cool and i'll taste it then but have some questions for more experienced jam makers:

1. Does plum jam crinkle in the setting test like strawberry jam does? Was I waiting for the wrong thing to happen?

1. could it be that I didn't boil furiously enough at first (did later, but it didn't rise like the strawb jam did)?

1. Any other ideas or suggestions as to how to improve on my next batch (have tree full of plums so ideal jam making education...)

Thank you!

I always use jam sugar TBH-then I can get away with less, as I like quite a tart plum jam. Yes, boil at first, and it should crinkle-though also I prefer a soft set jam so I don't go too mad!

Think it's down to preference, but the proper jam sugar is your friend here.

And I could do with some plums:)

Did you keep the stones in? You need the stones for the pectin that sets the jam (I get dh to spoon out the stones before bottling!)

Thank you . Do you know off top of head how much jam sugar you would use per kilo of plums? All the recipes I've found say normal sugar as plums high in pectin - but like you I wouldn't mind a bit more tart - think this one is very very sweet!

Ah, thanks sexy - no recipe said take them out but put kernels in which i did...

I never use jam sugar, but I also never add liquid to cook the fruit....well maybe a half cupful to stop it burning but never any quantity.

all jam should do the wrinkle thing, otherwise you have not reached setting point

I think the stones are supposed to float to the top so you skim them off, but i usually cut mine out and let them float in the jam, tied in a scalded cloth.

and sugar to fruit is usually equal quantities, but you can go down to 1fruit to three quarters sugar but it may be a softer set.

thank you. what if you want the kernels in? do you cook the stones and then get the kernels out and add back into the jam?

i'm using the river cottage preserves book btw. doesn't say anything about stones in.

It's important to use a mahoosive pan so that there is plenty of room for it to rise up. It sounds as if you boiled it for too long, tbh, if you've ended up with far less jam without a set - jam is best when it's boiled hard for the minimum time, IME, and that requires a big pan.

As for the stones - leave them in, then when it's cooled down a bit scrub up to your elbows and fish them out and pretend you're a country vet delivering a calf. Maybe just me who does that. It's surprisingly pleasant fishing around in warm goo. Tip: count your plums as they go in & then you'll know how many you need to get out

Thank you so much everybody! I did have a big pan but it didn't rise up the way the strawberry jam did the other week. I'll try with the stones in and boiling more furiously straight away. Someone let me know about the kernels!

I've always worked on the understanding that Pectin is higher in underripe plums than very ripe ones so ideally you need a mix. I halve them and leave the stones in, they are very easy to skim off the top. You can use a potato masher to feel/ make sure that there are no stones left in.l

Thanks Mis, and do you kernel, or not kernel. Any kernels anyone?

I don't know what you mean by kernel. Please elaborate.

it's the kind of nutty thing inside the stone that you sometimes get in plum jam. So my recipe says crack the stones with nutcracker, blanche the kernels and rub the skin off then add to jam. Just been surfing other recipes on internet and there a lots like this, so maybe the kernel contains pectin too.

Can you get hold of any damsons? If so try a 50/50 damson and plum mix - will be lushious but tangy and you shouldn't need jam sugar or pectin - Damsons will set anything! But fishing the stones out is a bugger - I usually soften damsons in a small amount of water first (10 mins ish?), fish out all the stones, and then carry on and boil up with sugar.

I usually lob a peeled Bramley in with all the plums. Doesn't make the finished jam taste like apples and helps it to set.