So over the winter, I developed an allergy to citrus. It sucks. Canning season is here and it seems like every recipe I love calls for lemon juice. I know that in some things the lemon juice is required to acidify the food to make it can properly, but in jam it is usually used for flavour.

I know I can use vinegar to replace the acid but I am trying to think of alternatives to lemon for flavour. So far I have though of cider vinegar and lemon balm, and I am currently experimenting with them in a batch of blueberry butter.

For the blueberry butter I have also thought about using either puréed cranberries or 100% cranberry juice.

Can anybody think of anything else to add a hint of sour to jams?

In the case of strawberry jam I have read that the citrus adds pectin to help things set better, so I might need to add some apple or something.