Lemon Juice (Best Option)
1 tablespoon lemon juice per 1 tablespoon white vinegarLemon juice contains citric acid, which reacts with baking soda to produce carbon dioxide, helping doughnuts rise and develop a light texture. Its acidity level is close enough to white vinegar to maintain proper chemical reactions in the batter.
For best results, use freshly squeezed lemon juice to avoid any off-flavors from bottled juice. The citrus aroma can enhance the doughnut's flavor subtly without overpowering it.
Compared to white vinegar, lemon juice may impart a slight citrus undertone, which can be pleasant in most doughnut recipes, especially those with complementary flavors like vanilla or cinnamon.