How to make jam with strawberries (or other fruit)

Every June while I was growing up, I used to make strawberry jam with my mum. She was a working woman, so it was a process we split into two parts: in the evening, washing and prepping the berries; early the next morning, cooking the jam and sealing the jars. It was the best jam ever.

It still is! I seal my jars in a water-bath now, rather then using messy (and leaky) paraffin. Sometimes I use the same evening/next morning plan, or sometimes I prep in the morning and cook/seal that same evening. In either case, the process is still the same, starting with perfect berries at the peak of freshness.

It’s not a difficult process, and not even that time-consuming. Make jam in small batches – I never make a batch larger than 4 quarts fruit, because the quicker jam cooks, the fresher it tastes, and a large batch takes much, much longer. Besides, I have a small family, so why would I want to make an industrial-sized batch of jam?

So, how do you do it? I’ll explain it here step by step, and post a short-form recipe as a separate posting.

Prep the Berries

Handle the berries as gently as possible. Fill a sink or basin with cool water, add in the berries, 2 quarts at a time. Swish them around a bit, to dislodge any sand. Pull from the water and put on towel-lined cookie sheets in a single layer.

Remove green stems and leaves. Slice berries horizontally into a large 4-cup measuring cup. Pack the berries down a little bit. For every 4 cups of berries, you’ll use 3 cups of sugar. Layer the berries and sugar in a large non-reactive kettle. When all the berries and sugar are in the kettle, stir the sludge until thoroughly mixed, and then let stand, covered, in a cool place (or in the refrigerator) a minimum of 3 hours and up to 12 hours.

Prep the Jars and Lids
empty jelly jarsYou will want the jars and lids to be ready when you begin to cook the jam. You will need spanking clean jars and lids. Since I have the luxury of a dishwasher, I put the jars through a dishwasher cycle, to have them hot and ready to use. I put the flat lids in a small saucepan, cover them with water, and bring the water not quite to a boil. They need to be kept at 180 degrees for at least 10 minutes. Have some clean flatweave (lint-free) dishtowels ready. Have clean screw bands ready, but it’s not necessary to heat them. Just make sure they’re not rusty or bent.

Cook the Berries into Jam

You will need a much larger pot than you might think you would – while making jam, the fruit and sugar will expand at least double, and as much as triple! Plan ahead, use a big pot. Wider is better than taller, because you want to encourage evaporation. Make sure that there is plenty of liquid in the pan as you begin to cook, and stir often at the beginning, so that no sugar will stick and burn on the bottom. I myself use a large 12-qt stainless steel kettle, and a long-handled stainless steel spoon; these make the job easier and will last forever. The butter is added to the fruit to control foam-up. Start with medium heat, and then adjust to bring the mixture to a violent all-over boil, and keep it there. When the color and/or texture changes, begin to check if the jam is ready.

Special Note: How To Tell When Jam Is Done

As the jam cooks, the texture of the liquid will change. Spoon some of the liquid (not the pulpy fruit) and hold the spoon up above the steam. Let it drop back into the kettle from the side of the spoon. At first (see left) it is light and thin. As it thickens, one drip will thicken into two, and if you cook it more, it will sheet off the spoon in a glob (see below). For my jam, I prefer the texture somewhere between the middle and the right picture.

test for jam

The definitive test, for me, is the “Wrinkle Test”. When you start to cook the jam, put a saucer or small plate in the refrigerator to chill. When you think the jam may be ready, put a little dab of the hot stuff on the chilled saucer, and put it back in the refrigerator for 2-3 minutes. Take your jam kettle off the heat while you do this so it doesn’t cook down further. When the minutes are up, check the jam: when you push at it with your fingertip, do little wrinkles show on the surface? If so, it’s ready. If not, it needs to cook a bit more.

Fill & Seal the Jars

Line up your hot sterile jars on the counter near your kettle. Put a funnel in the closest one, and ladle hot jam into the jar just past the bottom of the funnel, or as needed to leave the right amount of headspace. Be careful! That jam is boiling hot, and will act like napalm – don’t let it get on your skin. Carefully move the funnel to the next jar, and repeat, until all your jars are full. Helpful hint: I always prepare 1 more jar and lid than I think I’ll need, just in case. Better to have one sterile and ready, than to run out of space. If you have an odd bit left, you can put it in a bowl or custard cup, and just refrigerate it, planning to use it during the next week or so. In my house it would last about 2 days.

When all your jars are filled, make sure that the rims are clean: wipe them with a clean damp cloth. Particles of food on the rim can mean that the jar won’t seal right. Now get the lids out of their sterilized hot-water bath. I use my magnetic lid-lifter and fish them out one by one. Cover each jar with a flat lid (rubber gasket down). Attach screw bands to each jar only until a point of resistance is met – finger right. Don’t screw them down as far as you can get them to go! Just finger tight.

Handy Tools

At this time of year, most hardware stores, some grocery stores, and just about all Wal-Marts carry canning supplies, including jars, lids, and some great tools. Invest in a set of canning tools once, and you’ll use them for years and years. The most common kit available these days comes from Ball (the jar maker) and includes a funnel for filling the jars, a lid-magnet to get lids from hot water, a headspace gauge and airbubble popper, and a jar-lifter, all for about $10. I highly recommend this kit.

Into the Water Bath

As you start cooking your batch of jam, have your big canning kettle ready, too. I fill mine with about six inches of water, which I reckon will come up 2 inches over the tops of the filled jars, once I get them in there. Start to heat this water while the jam cooks.

When the jars are filled and the lids and bands on, put them in this hot water one by one. Your jar lifter is the perfect tool – don’t try to use tongs, and never handle a jar by its lid or band. Put the jars either in a canning rack, or one by one place them in the water in the kettle, spaced evenly if you can. The water should cover the jars by 2 inches – if it doesn’t, add more hot water until it does. Cover the canning kettle, and bring it to a rolling boil. Set a timer, the jars need to be processed in boiling water for 15 minutes. If the water stops boiling, bring it up to a boil again and re-start the timer.

After 15 minutes of boiling, remove the jars one by one from the kettle of water. Put them upright on clean dry dishtowels on your counter with 1 to 2 inches of space between each jar. Leave the bands alone! Don’t touch them, because it can interfere with the seal. Let the jars cool naturally. You will most likely hear a series of cheerful POPs as the lids snap sealed.

After the jars have cooled for 12 hours or so, test the seals. The simplest way is to press on the center of each lid. If the center of the lid does not flex up and down, the seal is complete.

1 Response

  1. […] explain here in detail. Readers who have been following the blog for a long time know I’ve written about this before. Nothing much has changed – it’s still a 3 step […]

  2. […] the preserves to the boil again, stirring often, and cook until it passes a jelly test. (see How to make jam for information on the jelly test). In my kitchen today, it took about 10 minutes more. Remove […]

  3. […] How to make jam […]

  4. […] how to make jam (with berries or other fruit) […]

  5. Consider yourself read. It looks like a good recipe for jam. I’m kinda on the watch for a recipe for freezer jam that uses artificial sweeteners, as Tom and I are diabetics. So far, no luck.

    Anyhoo, good luck with the blog, luv.

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