Blackcurrant jam is one of those things that you just can’t find in stores. While you can argue whether or not canning is worth the time or effort, you cant argue with the fact that if you want blackcurrant jam you likely have to make it yourself. It is one of my favorite jams, and it’s a sad year when I don’t make time to put up a big batch.
Our woodland homestead is shady and wooded, which is the perfect place for growing blackcurrants. If you don’t have them growing in your backyard, blackcurrants are popular at farmers markets and pick-your-owns. They’re becoming more popular in the US with the rise of the local food movement because they’re an easy crop to bring to bear without spraying or tending.
Blackcurrant jam has a warm spicy flavor that’s unique to these deeply colored fruits. The fruits have enough pectin that they don’t require any added pectin, but they will require a good bit of sugar to balance their astringency. For sweet fruits, I always reduce the sugar by half or more, but blackcurrants don’t make a good low sugar jam.
Even if you don’t have a sweet tooth, be careful about reducing the sugar in a blackcurrant jam recipe. Start with 3/4 the amount it calls for and try it before you make a bitter batch of under sweetened jam.
Most recipes say to simmer the blackcurrants with sugar for about 30-45 minutes, until the jam reaches 220 degrees F. I’ve tried using a thermometer, and cooking the jam all the way to 220 degrees results in a paste that’s so thick I can barely get the spoon into it. That batch was pretty well ruined, so I don’t follow that advice anymore.
Start by simmering the berries with the sugar. They’ll release their juices quickly, and you’ll have a pot of juice with floating berry skins in about 10 minutes. After that, it’ll start to foam heavily. Watch it carefully at this point because it has a tendency to boil over. Make sure the pot is no more than 2/3rds full and stir it down if it starts to rise.
At about 20 to 30 minute of cook time, the jam will stop foaming. The texture will visibly change and it’ll start to look a bit silky. It’s still boiling, but the bubbles are big bubbles that grow large in the sugar syrup before popping. This is the jam just starting to form. Cook it just another minute or two more, and then load it into canning jars.
I’ve taken the temperature of the jam at this point, and it’s about 216 to 217. That’s way before the supposed “gel stage at 220” that most recipes call for. I kept wondering what others are doing here, and how they can possibly make it all the way to 220 without ruining their jam.
Then it dawns on me…altitude. When we can our maple syrup, the finish temperature is below what’s recommended for sea level because we’re at around 1,000 feet in elevation. The boiling temperature of water decreases by about 1 degree F for every 500 feet of elevation, meaning that water boils at 210. With that in mind, my blackcurrant jam finish temperature should be around 218. That’s a lot more believable.
Since I’m finishing it at around 216 to 217, instead of my gel stage at 218 I assume others must like very thick blackcurrant jam. This jam came out quite thick, and if I take the temperature next time, I’ll be sure to finish it a bit earlier.
Regardless of how thick you like your blackcurrant jam, be careful to check your elevation and adjust your finish temperature for altitude to avoid ruining a batch of jam. It takes a long time to pick these beauties, and it’s a shame to ruin even a pint, let alone a whole batch.
This blackcurrant jam can be made with simply the fruit and sugar, but I like the flavor when I add a bit of lemon juice. The lemon juice is optional, and it’s not necessary for safe canning.
So the real question, does it get the toddler seal of approval? To be fair, my little one likes tart fruit, and she’ll eat the blackcurrants right off the bush. Still, she ate it right up saying, “It tastes just like strawberry jam, but sour, and that’s really good.” I’m not sure that’s the best description, but it’s hard enough for an adult to accurately describe the flavor of a blackcurrant, so I’ll cut this 3-year old a bit of slack.
Blackcurrant Jam Recipe for Canning
This recipe makes a simple blackcurrant jam that's just sweet enough and plays up the spicy flavor of the blackcurrants. One batch yields 8 half-pint jars, but can easily be divided in half.
- 3 lbs blackcurrants, stems removed roughly 9 cups
- 2.5 lbs sugar roughly 5 cups
- 3 tbsp lemon juice optional
Add the blackcurrants to a thick bottomed pot and simmer on low for about 10 minutes until they begin to release their juice.
Add sugar and lemon juice (if using). Simmer for about 30 minutes, stirring frequently to prevent boiling over. It will foam heavily, make sure the pot is no more than 2/3rds full when you start.
When the jam stops foaming and begins to thicken, cook for another few minutes before pouring into canning jars. If you're using a thermometer, the jam should be roughly 218 to 220 degrees F at sea level. Be sure to adjust for altitude! See note above.
Load into half-pint canning jars leaving 1/4 inch headspace. Attach 2 part lids and process in a water bath canner for 10 minutes. Or, alternatively, store in the refrigerator and use within a month or two.