Blackcurrant Jam

1.Prepare Berries and Sterilize Jars:Prep Time: 25 min | Effort: Hand Prep.

Pick through the blackcurrants, removing leaves, stems, and small twigs (“strigging”). Rinse under cool water and drain well. Place your clean glass jars into an oven preheated to $140^\circ\text{C}$ ($285^\circ\text{F}$) for 15 minutes to sterilize, and place 2 small saucers into the freezer.

2.Soften Berries & Extract Pectin:Cook Time: 15 min | Heat Intensity: Medium Simmer.

Transfer the washed blackcurrants and 600 ml of water into a large, heavy-bottomed pot. Bring to a boil over medium-high heat, then lower the heat to a gentle simmer ($90^\circ\text{C}$). Cook for 12 to 15 minutes, crushing the berries against the side of the pot with a potato masher, until the berry skins are thoroughly tender and the liquid has reduced by about one-third.

3.Dissolve Sugar Completely:Cook Time: 3 min | Heat Intensity: Low Heat.

Turn the heat down to low ($60^\circ\text{C}$). Add the 1 kg of granulated sugar to the softened fruit. Stir continuously with a wooden spoon until every single grain of sugar is dissolved. Ensure no stray sugar crystals stick to the sides of the pot.

4.Boil to the Wrinkle / Setting Point:Cook Time: 8-10 min | Heat Intensity: High Rolling Boil.

Increase heat to high and bring the mixture to a full, rolling boil that cannot be stirred down ($104^\circ\text{C}$–$105^\circ\text{C}$). Boil rapidly for 8 to 10 minutes, stirring occasionally to prevent catching on the bottom.

Testing the Set: Remove the pot from heat. Drop a spoonful of hot jam onto a frozen saucer, wait 1 minute, then push it with your fingertip. If the surface wrinkles and holds its shape, setting point is reached. If not, boil for 2 more minutes and retest.

5.Skim Foam and Jar:Prep Time: 5 min | Labor Intensity: Low.

Remove the pan from heat. If surface scum/foam has accumulated, stir in 1/2 tsp of butter to disperse it, or skim off with a spoon. Let the jam rest in the pot for 10 minutes so the fruit distributes evenly throughout the syrup instead of floating to the top.

6.Seal and Cool:Prep Time: 5 min | Handling Hot Jars.

Ladle hot jam through a wide-mouth canning funnel into warm, sterilized jars, leaving 1/4 inch of headspace. Wipe the jar rims clean with a moist paper towel, apply lids, and screw on the bands until fingertip tight. Process in a boiling water bath for 10 minutes for long-term room-temperature storage, or allow to cool on the counter and store in the refrigerator.