High summer fruit season – with plentiful berries and stone fruit – is a paradise for making jam. I had been thinking of the delectable combination of peaches and raspberries, so-called peach melba, but with our weekly CSA harvest of a quart of organic blackberries, I struck out in a slightly different direction. Red raspberries would have added a light fruity touch to the peaches, like red currants do with apricots. But blackberries, like black currants, have an earthy depth. Would the peaches be overwhelmed? As it turned out, the peaches add a spark to the blackberries, partly because I left them chunky. The deep rich color and flavor of this jam was quite appealing.
I used the Christine Ferber method of making two jams and combining them at the end. She has a recipe for blackberry peach jam in her book Mes Confitures, but I objected to the volume of sugar, cutting it down considerably. I increased the amount of lemon, reserving the seeds and a piece of rind and adding them to the peaches to increase the pectin. The blackberries have plenty because they’re so seedy. I also cooked the blackberries longer than she did since I wanted to eke out as much of the juicy pulp as possible. And with the remaining blackberry mash, I made a small amount of blackberry vinegar.
Blackberry Peach Jam based on Christine Ferber’s method
For the blackberry jam:
1 qt blackberries (about 1½-2 lb)
2 c sugar
1 lemon, juiced, seeds reserved
For the peach jam:
2 lb peaches (6-8 medium)
1½ c sugar
1 lemon, juiced, seeds and half the rind reserved
Prepare the blackberries. Pick them over to remove any hard cores or leaves, and rinse them lightly. Place the blackberries, 2 c sugar and the juice of 1 lemon in a wide saucepan. Bring them to a simmer and cook for about 3 minutes, or until the juice renders and the pump is soft. Pour into a bowl, let cool, and refrigerate overnight, covered with crumpled parchment paper.
Prepare the peaches. Bring a pot of water to boil, place a bowl of ice water in the sink, and put the lemon juice in a wide saucepan that you’ll use for preserving. Put the lemon seeds and rind in a small muslin or cheesecloth sack and add it to the lemon juice. Dunk the peaches, one or two at a time, in the boiling water and then plunge them into the ice water. Remove the skin and pit and cut them into rough chunks, dropping them into the lemon juice as you go. Add 1½ sugar and bring the peach mixture to a simmer. Pour into a bowl, let cook, and refrigerate overnight, covered with crumpled parchment paper.
Make the jams. If you’re planning to can the jam using a water bath method, prepare the canning kettle, jars and lids. Place a saucer in the freezer for testing the gel. Cook each jam separately, bringing the mixtures to a boil and cooking on high heat for about 5 minutes, or until gelled. Remove the sack of lemon seeds from the peach jam and combine the two into one pan. Bring to a boil and re-check the set. Pour into warm prepared jars.
Water bath canning. Process the jars for 10 minutes after the water returns to a boil. Turn off the heat, remove the lid and let them sit for 5 minutes before removing them to a counter to sit undisturbed until cool.
Makes about 4 eight-oz jars or 8 four-ounce jars and a little extra.
Categories: Berries, Preserving, Stone fruit
PROSPECT THE PANTRY 
That sounds delicious. I hadn’t thought of preparing them seperatly and then mixing in the jar. That’s a great way to maintain the right acid level. Thanks!
Why use parchment paper atop the chilling fruit?
I find that it helps keep the fruit submerged and allows the mixture to breathe a little (versus cling wrap that traps moisture). It’s not absolutely necessary. I sometimes cover with plastic wrap when there are ingredients in the refrigerator (think onion) that might taint the flavor of the fruit. The parchment is a trick that I learned from Christine Ferber’s book Mes Confitures.