Lately, Trader Joe’s had been selling 12 ounce containers of blackberries for right around $3.50. For those of you who live in the Pacific Northwest, it might seem crazy to pay for good money for blackberries since come August, they’re going to be everywhere. But for those of us who live in less blackberry-rich environs, this is a very good price.
As a result, I’ve been making lots of preserves with blackberries. I did a batch scented with lavender, and another batch with cinnamon and nutmeg, like my mom always makes. I also did this low sugar blackberry rhubarb jam, encouraged by an email from a reader who asked if I’d ever done such a combination).
I really love how it turned out. Tangy from the rhubarb, rich from the berries, and just sweet enough with a relatively small amount of sugar. If you wanted to make this jam with honey rather than with sugar, reduce the amount to 1 cup and save 1/3 a cup to add at the end with the pectin.
Oh, and if you don’t want to spring for blackberries now, but can get them at a better price later in the season, you can still make this jam. Just chop up a pound of rhubarb now, put it in a ziptop bag, and tuck it into the freezer until August. Frozen rhubarb behaves beautifully in jams.
Low Sugar Blackberry Rhubarb Jam
- 1 pound of rhubarb finely sliced
- 1 pound 8 ounces blackberries (or two 12-ounce packages)
- 1 1/2 cups granulated sugar divided
- 2 teaspoons calcium water part of the Pomona's Pectin system
- 2 teaspoons Pomona's Pectin
- Prepare a canning pot and enough jars to hold between 4 and 5 half pints (yields vary!).
- Combine the rhubarb, blackberries, 1 cup sugar, and the calcium water in a low, wide, non-reactive pot. Stir vigorously to combine, with the intention of breaking up the berries. Let the fruit sit with the sugar for a few minutes, so that the sugar dissolves and you get a little syrupy liquid in the bottom of the pot.
- Set the pot over high heat and bring to a boil. Reduce the heat to medium high and cook until the berries break down, the rhubarb is on the verge of dissolving, and the liquid thickens.
- Whisk the pectin powder into the reserved sugar. Add the pectin-spiked sugar to the cooking fruit in two or three batches, stirring to integrate between each addition.
- Cook for an additional minute or two, until you see visible signs of thickening.
- Remove the jam from the heat and funnel it into prepared jars. Wipe the rims, apply the lids and rings, and process in a boiling water bath canner for 10 minutes.