This recipe worked perfectly. I had to heat the jam for about 15 minutes longer than the time that appeared in the recipe. Without a lot of experience, the “sheet test”  did not help me, I used to “plate test.” Without the “plate test,”  I would have reduced the jam to syrup since I do not have enough experience to use the “sheet test.” I did not have a granny smith apple, and I had 1 or 2 additional cups of strawberries. I used all the strawberries, and I used 1 1/2 Honeycrisp apples to make this jam. I wrote about discovering this recipe in my blog post Raspberry Jam Made With Pectin From A Fresh Apple.
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