Milk + Lemon Juice or Vinegar (Best Option)
1 cup milk + 1 tablespoon lemon juice or white vinegar (let sit 5 minutes)This substitute works because the acid in lemon juice or vinegar curdles the milk slightly, creating an acidic environment that reacts with baking soda to produce carbon dioxide, which leavens the quick bread. The moisture content closely matches buttermilk, preserving batter consistency.
For best results, use whole or 2% milk and allow the acid to sit in the milk for at least 5 minutes before using. Avoid using skim milk as it may affect richness. Ensure the acid is fresh to maximize reaction.
Compared to buttermilk, this substitute yields very similar rise and texture, with only a slight difference in flavor that is generally undetectable in quick breads.