Yes! Use any kind of citrus juice you like in place of the lemon juice in these bars. Grapefruit, blood orange, lime, or regular orange, and tangelo all work well. Use zest from the same fruit but I still recommend adding the lemon oil or lemon extract. If the juice is quite sweet, like orange and tangelo tend to be, reduce the amount of sugar to 1 cup + 2 tablespoons.