To get this deep color I added strawberry puree (purchased). I think I could have used much less for color, but the smell was gorgeous when cooking it. The strawberry actually held its own against the grapefruit. The jell set amazingly. It could have used a second strain as it was quite cloudy, but I was impatient. This recipe made a lot of juice, and the original says to cook it in two batches (I assume at the same time). That sounded complicated to me so I froze four cups of the juice for future projects. That left me with three cups of citrus juice, to which I added the strawberry puree, making four cups, which seems to be a standard number when making jelly.
(Side note: Interesting to note that Joy uses "jell point" whereas Ball uses "gel point." Who do you believe? Is it a matter of preference? I prefer jell to gel, because we're making jelly, no? Not gelatin. But that's me and my craziness.)
2 lbs. of pink grapefruit
8 oz. of oranges
1 cup of strawberry puree
7 1/2 cups of water
1/2 cup of sugar per cup of juice
Quarter the fruit and chop up fine in a food processor. Add fruit and water to heavy pan, bring to a boil, then lower heat, cover and simmer for 1 1/2 hours. Strain. Measure three cups of juice, add strawberry puree. I let this cool for several hours, only because I wasn't ready to make the jelly yet. You could move right along and add it back to the pot with 1/2 cup of sugar for each cup of juice. Bring to a rolling boil, and cook until jelling point is reached. Ladle into hot jars and process for ten minutes.
This tastes like a rosy, very tart grapefruit sprinkled with a little sugar and maybe a small dollop of strawberry jam.