An Illustrated Plum Jam Recipe

This is a straightforward guide to making jam at home. I realise that there are about a million "instructionals" on YouTube showing exactly the same thing, but I reckon that there's always room for one more. ;-)

The basic tools and supplies you'll need. Clockwise from the left, we have a scale, a bucket of plums, sugar, a couple of big stock pots, a colander, a paring knife, and a wooden spoon. (I don't know how that butter knife ended up in the picture).

Rinse the plums in cold water, to remove any dust, leaves, and bird poop.

We'll be stewing the fruit to separate the pulp from the stones and skins. This process will go a bit quicker if you cut the plums on either side of the stone.

Removing the second side.

This particular batch of plums varied in ripeness from "slightly green" to "water-bomb of plum juice". If you don't have a few centimeters of juice at the bottom of the pot when you're done, you should add a little water to prevent the fruit from burning.

Bring the fruit SLOWLY to the boil. If you try to hurry this step, you'll end up with charcoal in the bottom of the pot which will ruin the jam's flavour.

It's a good idea to keep washing up pots and pans as you go, particularly in a little kitchen like ours.

Put your second (empty) pot on the scales, and adjust them to zero. (A clean plastic bucket would probably work just as well as the second pot, it's just going to be used to hold the fruit pulp for a couple of minutes).

The stones and skins have separated from the pulp, so now it's time to strain them out.

Pour the glop into the colander.

It's always a good idea to pour AWAY from yourself, as you'll get less badly burned if you happen to drop the pot.

Use your wooden spoon or some other utensil (Mrs Humble is using a potato masher here) to get as much juice and pulp out of the glop as possible.

That's about as much as we're going to extract from this batch.

Even with all of our care and stirring, we still had a little burning on the bottom of the rendering pot.

That's the first stage completed, we now have strained fruit pulp and we're ready to make jam.

The leftover skins and stones.

We ended up with 7.2kg of fruit (that's 15.84 pounds, for you poor backward metrically-challenged folk). ;-)

There's not enough room in the small pot to make the jam, you want your pot to be no more than half-full at this stage. We washed the big pot and poured the pulp back in.

At the stage, the jam will be a trifle bitter.

Add some sugar. The usual standard is to add an equal weight of sugar to the pulp (in this case, 7.2kg).

I use lemons rather than pectin powder to help the jam to jell (the skins of citrus fruit contain pectin). It also adds a nice "tanginess" to the flavour. 1 lemon per kg seems to work pretty well, but I only had 4 lemons on hand for this batch and it turned out a bit runny. Make sure that you remove any labels from the lemons first.

Squeeze the lemons into the pot (you can leave the juice out if you don't want so much of a lemon flavour in the jam).

Use a strainer, and make sure that you get all the seeds out of the lemon skins.

Drop the lemon skins into the pot. We want to render the pectin out of them to make the jam "set".

As well as being too small for the batch, the smaller pot has a non-flat bottom that doesn't work well on the electric range.

I spent the off-season gathering, washing and de-labelling jars. The cupbord is full of Fowler jars, the boxes are full of screw-top jam jars. I hope that this will make for a much less stressful preserving season.

Put a small plate or saucer into your freezer. You'll use this to test the "set" of your jam.

Slowly bring the pulp/sugar/lemon mixture to the boil. You'll want it at a nice slow boil, like this.

Once boiling, set a timer of some kind to remind you to give it a stir every 15 minutes or so.

Test the "set" of your jam by spreading a teaspoonful across your cold plate.

Let it cool for a minute, then see how sticky it is when you tip the plate up vertically. This batch took about 2 hours to get to a reasonable thickness, mostly because of too few lemons. It was still a bit too runny.

Place your clean, empty jars in a sink full of hot water. You need to do this because otherwise the cold jars will crack when you pour the still-boiling jam into them. Most glass jars can handle a thermal shock of 50oC, so hot water from the tap should be sufficient.

Fill the jars with jam, to within about 1cm of the top. We use a pyrex jug for this task, other people use funnels or ladles or skilful pouring techniques, use whatever works best for you. ;-)

Wipe the rims of the jars with a clean cloth, to ensure a good seal with the lid.

Screw the lid on to fingertip tightness. You don't have to wring its neck, just make it the same as you'd screw the lid back on a jar of stuff that you're keeping in the fridge.

Some people let the jars cool and seal at this stage. I prefer to give them 5 minutes in a boiling-water bath to kill any bugs that were in the jar, and also to ensure a good tight seal.

A big pot of water on the stovetop will work perfectly well, provided you use some kind of insert to keep the jars off the bottom.

We've got this Fowlers Vacola Electric Preserving Unit (essentially a 19 litre electric urn), so we use it instead.

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