Blackberry Jam and Lessons Learned While Jamming

6 Aug

finished jam

I’ve wanted to make blackberry jam for a while now, and yesterday morning my dad bought 15 pints of blackberries at the flea market. It felt like my time had come. I’ve only once made jam before, but I felt more confident this time around. The hardest part about making jam is knowing when it’s set, and that’s still a stress-inducing time for me. It’s just something I’ll have to get used to. I again used a recipe from Food in Jars, and she still has yet to fail me. This recipe makes a small batch of six half-pints (plus a tiny amount extra) of delicious blackberry jam. Let’s move onto the jammin’.


You can find the original recipe here. I made a couple minor alterations on my own, but I essentially stayed true to the recipe. You will need:

  • 6 c. blackberry pulp (from straining berries or just mashing if you like seeds)
  • 4 c. sugar
  • 2 tsp. cinnamon
  • 1 tsp. freshly grated nutmeg
  • 1 lemon (juice and zest)
  • 1 package liquid pectin (half of the box)

straining berries

Before you start, put your big ol’ canning pot on the stove with more than enough water inside to cover the jars you’ll eventually add. You can also put the jar lids on the stove to let the sealing compound soften. Don’t let the water for the jar lids boil; just let it get hot. For the fruit, you’ll need to strain or mash your berries to release all those juices. I had some berries that were going to mold by tomorrow and some berries that were absolutely beautiful and delicious. Because of this, I decided to strain the almost-moldy berries by pushing them through a strainer with the back of a wooden spoon (shown above). I used three cups of the juice squeezed out of these berries and three cups of mashed berries. You can use all strained or all mashed or a mix of the two like I did. The strainer is to eliminate seeds obviously, so just go by your preference.

berries and sugar

After you have your six cups of berries, add the fruit and sugar to a pot and stir. The more surface area a pot has, the better it is for jam-making, so use the widest pot you have that will hold the mixture. Put this over heat, and let it come to a simmer.


Once the mixture is simmering, it’s time to add the lemon and spices. Stir to combine and let the mixture come to a boil. Once boiling, you kind of have to use your mad jam deduction skills to decide when it’s starting to thicken up. I personally let it boil (while stirring it frequently) for about 20 minutes, but this really varies from batch to batch. Just wait until it looks sort of syrupy and less like the liquid it was at the beginning. For me in my particular pot, it took about 20 minutes.

busy stove

Look at all this madness! Pots! Lids! Jam! Once you notice the jam start to thicken, add the packet of pectin and get the jam back to a rolling boil. Let the jam boil for at least five minutes after you’ve added the pectin to ensure it activates. I let mine go for around 15 minutes.

testing for set

If you’re not sure your jam is set, you can do a couple things to test it. For starters, the ideal set temperature is 220 degrees, so if you have a candy thermometer, use that to see whether you’re up to temperature. Another test is the plate test, which you can see above. Before you start cooking, put a couple dessert plates in the freezer. When you think your jam is set, put a spoonful of jam on a plate just taken out of the freezer and let it sit for a few minutes. If at the end of those few minutes your jam has something of a skin and develops a certain solidity, then it’s ready. I also combine this test with the sheet test, which you can see above. The real sheet test is when you take a spoon and dip it in the jam. If it comes off in a sheet rather than droplets, it’s ready. But I feel that I can do this test with what’s on the plate too. As you can see, my jam is falling in a sheet rather than separate drops. It’s like a double-check for myself.

canning pot

Once you feel your jam has set, ladle the hot jam into your clean jars. If you have a little extra that doesn’t fill a half-pint, don’t bother to can it. Just throw a lid on it, and put it in the fridge. For the jars that are full, wipe the rims with a washcloth dipped in the hot water from your warming lids, and put a lid on each jar. Screw the bands on about halfway — not tight — and put the jars in the canning pot to process. The water in the pot should be boiling, and the jars should never touch the bottom of the pot lest they crack. Process the jars for 10 minutes, then take them out and put them on a dry towel to cool and finish setting for 24 hours. This is the part where you get to hear the charming pop, signifying that they’re sealed. If they don’t seal, fret not. You can throw an unpopped jar or two in the refrigerator and eat them first. But don’t throw them in the fridge yet. The jars can take up to 24 hours to actually seal, so if it doesn’t happen right away, not all hope is lost.

blackberry jam finished

Look at that beautiful jam. Now it’s your turn. Here are some pro tips for the road:

  • If you get jam all over the stove and counter and tea kettle and walls like I do, use a washcloth dipped in boiling water to quickly clean it off. Water from the canning pot works well.
  • If you get berry juice or jam on your clothes, don’t freak out. First of all, make sure the colors in whatever you’re wearing can be exposed to hot water. If you’re unsure, test this method on an inconspicuous part of your clothing first. Boil water in a kettle or another pourable device. Set up your item of clothing over a strainer or a wire rack in the sink with the stain facing up. Pour the boiling water over the stain until it disappears then wash as usual. That’s it. This also works for wine stains or any other berry-related stain.

2 Responses to “Blackberry Jam and Lessons Learned While Jamming”

  1. Kitchenjammin August 7, 2012 at 11:21 AM #

    Nice tip on the fruit stains — I made the mistake of wearing a light blue t-shirt on blueberry jam day last week.

    And as for jam not setting, you can always call it a syrup and use it on pancakes, plain yogurt or vanilla ice cream. 🙂

    • sreagle August 7, 2012 at 12:21 PM #

      Very true about the syrup! One of the batches of strawberry jam I made recently is in a state between perfectly set and syrup, and it’s absolutely amazing on ice cream.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: