Trifoliates are also known as bitter orange, sour orange, and various other names. They can be good to use in marmalades or in teas, but they are not good for fresh eating. They're a cousin of citrus but are not true citrus trees.

These are mainly used for grafting stock, because of their cold hardiness.

I have about a 15' trifoliate orange myself and mainly keep it around because it really smells great when in bloom - the same reason I have sweet olive tea trees.

They have lots of thorns, and the fruit doesn't stick on the tree long after ripening. So, you can't use these the same as a sour kumquat, where the fruit just stays on the tree for long periods, for an all-year show.

Since the fruit all drops around the same time, it can be messy, and what's worse is that no wildlife seem to eat it.

Hope this helps.

stacey
Trifoliate fruits are mostly seed, and what little pulp is present is exceedingly sour - and there's a particularly nasty & objectionable oil present in the rind which makes it almost impossible to make any sort of culinary or other edible use of the fruits.

I've seen recipes for making trifoliate lemonade - using the juice of one trifoliate orange, 200# sugar and 55 gallons of water. LOL
But you'd probably still have a disagreeable aftertaste from the oil in the rind, no matter how careful you'd been in juicing the fruit.