I grow Actinidia arguta, also known as hardy kiwi or kiwi berry at my parents house. Well actually they grow themselves. I bought plants on clearance at whole foods 8 years ago and planted them different places across town. These are the only ones I know have survived, but I should probably check my old house in West Philly sometime. They grow like a grape vine and are well suited to Philadelphia's climate. They grow vigorously. It is hard to find much information about growing them or processing their fruit. They taste like a kiwi but with a smooth skin that slightly wrinkles as they ripen. They have tons of vitamin C and are delicious. I prefer them to "normal" kiwi.
I am always hesitant to invent my own canning recipes due to long term storage/ safety concerns but couldn't find any for kiwi berry. The best recipe I found was in the Ball blue book for conventional kiwi jam set with pectin. However once I multiplied out that recipe for the quantity of kiwi I had, I realized I didn't have enough pectin and it was an absurd amount of sugar. It was useful if I wanted to really stretch my crop, I could have made 2 dozen half pints by that recipe but that seemed unnecessary. Instead I opted to make up a fruit butter recipe, with Ball's acidity recommendations of 1 Tbl lemon per cup of fresh fruit. I used sugar quantities based on the apple butter recipe I had recently made. I cooked it down a really long time which should make the finished product safer , as the water cooks out the ratio of sugar and lemon to fruit increases, as well as improve the texture without needing to add pectin. I have no moral/healthful issues with pectin I just don't use it much so it makes me a little nervous.
2 1/3 C water
9 C kiwiberry (3.5lb)
1/2 C +1 Tbl (9 Tbl total) lemon juice
2 1/4 C sugar
Bring kiwi berry and water to a boil, turn down to medium low and simmer for 20 mins. Puree with an immersion blender and add sugar and lemon juice. Continue to simmer for 1 hr 30 mins. Stir often or the bottom will burn. You can try to rush it at higher heat but you'll probly burn it, so dont get greedy. Perhaps if you dont add quite as much water at the start, you can shave some time off the cook down but it really isnt much water for how much fruit is there...
Testing if it is properly gelled up can be a tricky thing because its gonna be really liquidy while its hot no matter what. So do this: puut a spoonful of jam on a plate. Put the plate in the freezer for 5 minutes or so. That isnt enough time to freeze it but it will cool down that small amount sufficiently. Take the plate out of the freezer. Run your finger through the jammy blob. Eat it. If the jam stays parted without weeping liquid into the center, it is set. If it weeps, keep on cookin' and stirrin'!
Sterilize jars and caps. Water bathe for 15 minutes. Take out and make sure all the lids pop. Eat fancy toast until you run out.
This recipe turns out a lovely sweet tart finished product. you could probably add more sugar without destroying it but I find it pleasantly tart and still a little sweet at this level. It is more tart than most store bought jams though.