You frequently see lemon or lime juice in savory recipes. Why is grapefruit juice ignored? Is it just too tart? I don’t drink it, FWIW.
I imagine that grapefruits have historically been harder to come by than lemons and limes.
Or, it could possibly have something to do with the fact that the bitter compounds in grapefruit juice get more bitter as they sit after being squeezed. Seems to me that might make it hard to effectively gauge how bitter a dish might be. Most of the time, grapefruit juice is used in drinks where it’s squeezed to order, rather than being pre-squeezed, so it’s as non-bitter as possible.
Obviously, when I said “tart”, “bitter” was the word I was after. My OP also forgot to mention OJ being used, but not purple grape juice.
I’ve seen grapefruit juice used as a meat tenderizer.
Grapefruit Marinated Fajitas
Grapefruit, Ginger and Honey Flank Steak
Lemon/lime juice is much more acidic than grapefruit; it’s used to add a zing to a dish, much like vinegar. Grapefruit juice isn’t acidic enough to add the zing, and it also (as you said) has a bitter element.
It’d work in some dishes (Grapefruit chicken, anyone?), I’m sure. Bitterness plus a bit of citrus sweetness isn’t a bad thing. But it’s just not as versatile as lemon or lime.
Note–grapefruit, and it’s juice are no-nos, when you take certain medications.
There’s a citrus salsa called xec that is fantastic with grapefruit-marinated pork. Here’s a recipe for it with fish.