A starch-thickened cherry pie filling doesn’t taste tart enough, so more lemon juice is added. Why is it best to add the lemon juice after the cherry pie filling is cooked and cooled? Even better than...

A starch-thickened cherry pie filling doesn’t taste tart enough, so more lemon juice is added. Why is it best to add the lemon juice after the cherry pie filling is cooked and cooled? Even better than adding the lemon juice at the end of the cook time is to use a starch that is stable to acid. What starch is the best choice for acid stability?