Making Plum Jam/Jelly

I like sweet food, and jam (it is never called “jelly” in New Zealand) is one of my favorites.  Smear jam on homemade bread that’s gone through the toaster, and you have a delicious lunch or snack.  Making our own jam is even nicer, because we can sweeten it to our preferred taste, though Andrew likes things less sweet than I do.

We have so many plums this year that we simply could not figure out what to do with them all.  Even with the birds eating more than half of them, we still had more plums than we could eat, and even more than we could seem to give away.  So, preserving them is the option that came to mind, and instead of simply stewing them and putting them into jars or freezing them for storage, I decided to make some jam.  And then I got a bit carried away and have so far made over twenty jars of plum jam.  Yummy.

Stewing plums to make plum jam/jelly in New Zealand

Stewing and mashing plums. Skins and jam setting mix on the counter.

The first step (after collecting and washing the plums) is to stew them.  It is a simple process to shuck the fruit out of the rather tart skins by simply cutting a slit down one side of each fruit and then squeezing out the insides into the pot.  Then I simmer the fruit until it is soft and squishy, mashing the mess to squeeze out all the juice.

Jam making in New Zealand - straining plum juice from pulp

Straining juice from pulp

After stewing the mess until all the juice has been mashed out of the pulp, I strain the stuff in the pot, to remove the pulp, so that only the juice remains.  In the USA, this is the difference between jam and jelly – whether or not pulp remains in the jam.  Strained juice makes jelly, and juice and pulp make jam.  I prefer no pulp.  In New Zealand, though, “jelly” is what we in the USA call “Jell-o” or “gelatin”.  “Jam” is the word for encompassing term.

The first time I made plum jam, I simply measured the juice and added an equal volume of sugar.  That didn’t set up thickly, though.  I was missing pectin.  That recipe (equal amounts of berries and sugar) worked well when Andrew’s parents made raspberry jam while they were visiting us.  But I guess berries have more innate pectin than do plums.  So, I bought some jam setting mix at the local grocery store.  We haven’t yet found anywhere that will sell straight, unadulterated pectin.  Everywhere seems to sell only this jam setting mix.  So, for that first batch, I opened all the jars of jam and poured it all back into the pot, brought it to a boil, added the pectin (jam setting mix) and boiled for six minutes, after which I put back into jars.  That worked well.

For the next three batches of jam, I add the pectin as well as the sugar.  The jam seems to thicken even better if the pectin is added and boiled before adding the sugar (as the directions say on the jam setting mix packet).  So, I do that now.

New Zealand jam making - boiling juice and sugar

Boiling jam

Anyway, measure the volume of the juice and put it into a clean pot.  When it reaches a boil, add the pectin (jam setting mix) and bring it to a boil again.  Then add the same volume of sugar as there is juice (more or less according to one’s preference in taste), and boil the mixture for six minutes.  Then let the jam cool for ten to fifteen minutes (again, according to the jam setting mix packet’s directions) before pouring it into the sterilized jars.

Home-made plum jam in New Zealand

First batch of plum jam.

Since preserve jars are very expensive here, we’ve been using old jam jars, mostly.  We have just a couple of small Agee brand preserve jars and used those as far as they went.  Using a one litre (about a quart) measuring cup with a nice pour-spout, I fill the jars and put on the caps and tighten them as tightly as I can.  I don’t know if they need to be tightened that tightly, but better safe than sorry.

To sterilize the jars, we wash them, then fill them with hot water from the tap and let them “soak” awhile, and then finally fill them with boiling water.  Everywhere I look, on the internet, on the back of the jam setting mix packet, and even from Andrew’s parents, I find that the proper way to sterilize and heat the jars is in an oven at 100ºC (212ºF, boiling point of water).  I really should try that one of these times.

Of all the jars of jam I’ve made (just over twenty), only three didn’t seal well.  This happened with two jars that were not filled all the way, since those jars were the end of the batch.  I don’t know what happened to the third jar, but since we are using used jars and used lids, I am very pleased that we’ve had only one real failure.  Those which do not seal well have to be refrigerated, just like opened jam you might buy at a store.

I’ve ordered new jars from a company in Wellington.  Arthur Holmes offers a very wide variety of jars and bottles, both glass and plastic, in many different sizes.  We chose the one-time use glass jars with screw on one-piece lids, rather than the nicer (and more expensive) preserve jars with two-piece lids.  We expect to receive our order this week.

As I mentioned previously, for the peaches, so far, Andrew has been simply stewing them, rather than making jam.  I am going to try making peach jam now that our plum harvest is slowing (the first tree is nearly entirely harvested) and the peaches are really beginning to ripen quickly.

It has been many years since I did any preserving (what I used to call “canning”, even though we used glass jars).  It is fun but a lot of hard work, “slaving over the stove for hours.”  And I sure do like the yummy results.


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