White Vinegar (Best Option)
1 teaspoon per 1 tablespoon lemon juiceWhite vinegar is a clear, mild acid that effectively replicates the acidity of lemon juice, which is critical for activating baking soda in doughnuts. This acid-base reaction produces carbon dioxide, helping the doughnuts rise and develop a tender crumb.
When substituting, measure carefully to avoid excessive acidity that could impart a vinegar taste. Mixing thoroughly ensures even distribution and consistent leavening.
Compared to lemon juice, white vinegar lacks citrus flavor but preserves the chemical function, resulting in doughnuts with similar texture and rise but a more neutral taste.