Blackberry jam making was my first go at making anything beyond a cobbler with this miraculous fruit. I'd been admonished about seeds, perplexed by articles fussing over how to remove them, which mill worked best, and admittedly I as a little worried at how I'd handle them. I made a few missteps, but putting on my black apron was the smartest thing I did all day.
My main mistake was thinking that I could put whole, fresh berries through the food mill. I didn't realize that they really needed to benefit from cooking before the seeds would begin to give from the berry flesh. Let's just say that the squirting of fresh berry juice gave me pause to consider my process. I cleaned out my food mill---and since it always comes up in posts, I'll mention that I use the KitchenAid food straining attachment to my stand mixer. Once I cooked the berries, the mill worked beautifully.
Due to quantity, I doubled my recipe and turned out a fantastic product. I really didn't know it would be such a hit, and now I'm sort of sorry that I waited so long to go for a second pick. Daughter ended up with almost 4 pounds of berries for a good friend, and I came away with just enough for a cold-pressed shrub. No complaints, I just feel bad that I don't have enough as I'd like to go around.
~5 pounds of berries
9 cups of sugar
9 cups of sugar
4 TBS lemon juice
2 pkgs. powdered pectin
1 tsp. butter (to reduce foaming)
Cook the berries in a non-reactive pot over medium heat until they're soft and begin to burst--about 15 minutes. Feed berries through a food strainer, mill or sieve. Discard the solids, and put the puree back in your non-reactive pot. Bring to a boil, add sugar, butter and cook until the mixture boils again. Skim off any foam. Add pectin, and bring to a boil once again. I tend to use a candy thermometer, and would cook until the blackberries reach 220 degrees. Turn off the heat, and ladle into sterilized jars, being careful to wipe rims, then adding lids and rings. Process in a water bath canner for 12 minutes at a rolling boil.
On a side note, this was the first time that my little girl helped in the jam making. She carefully counted out lids and rings to match jar quantities, sorted berries and stirred the pot. We both had a good time, and had 13 pretty, half pint jars to show for it.