What can I substitute for lemon juice in a recipe if I don't have any?

Do you have an citric acid in your cupboard?

Not everyone has a cupboard like mine, but I’m thinking that this could be excluded all together without any problems.

½ amount of white vinegar, e.g. 2 tbls. lemon juice = 1 tbls. white vinegar.

Lemon juice is just to give the blueberries extra flavor if they don’t have much. You could add a squeeze of orange or a bit of orange juice if you have some; otherwise I would just leave it out.

I agree with @aprilsimnel that vinegar works about the same. High acid content which tends to bring out the flavor more.

If you happen to have cream of tartar, that would work. It has a nice clean acidity, more like lemon juice than vinegar. Use one third the amount of the amount of lemon juice called for.

Lime juice will just about always work. Sometimes orange juice will work. If it’s something like salad dressing, you can probably use a little vinegar.

@perspicacious I am making blueberry pie.

If you have grated lemon rind, you could probably use some of that; if you just make the pie w/out lemon anything, I’m sure it will still be good!

I’ve never put lemon juice in blueberry pie. I suspect you can leave it out. If you’re going to use vinegar, I would use cider vinegar instead of white distilled; it’s milder.