Welcome to the boards, Hungry Charlie!! (Nice moniker there, too!)
The direct answer to your questions is yes-you can. A couple of ideas come off the top of my head….
You could make a Crabapple-Plum Jam this way:
6 cups of plums, pitted and chopped
1 cup of crabapple juice
1 tablespoon of lemon juice
1 package of powdered pectin
7 cups of sugar
Combine the plums, juices and pectin in a large, heavy and tall saucepan or pot and bring to a rolling boil over high heat, stirring constantly. Add the sugar, stirring to dissolve, and return to a rolling boil, then boil hard for one full minute more. Ladle into sterile jars, clean the rims, affix the lids and rings (not too tightly!), and process for about 15 minutes in a water bath canner, depending upon your altitude.
You could also make a Crabapple-Plum Jelly:
Place 3 cups of pitted and chopped plums into a medium saucepan, cover and simmer over low heat for about half an hour. Then strain in a sieve or through several layers of cheesecloth.
Combine 3 cups of crabapple juice with 1-1/2 cups of plum juice, 1 tablespoon lemon juice and 4 cups of sugar in a large, heavy and tall saucepan. Bring to a boil over medium heat and continue to cook until the mixture begins to thicken and gel. (This will take a while…a half hour or so perhaps.) Then ladle into jars, seal and process.
The age of your crabapple juice really concerns me, though. While it may taste fresh, it is still already a year old. The longest lifespan of anything that I preserve is one year, because I would much rather throw hard work away than risk the variety of food poisonings and botulism that age will produce in preserved foods.
I hope this helps get you started, Charlie, and I know others here will offer input, as well.
Happy canning!
