of yogurt or milk with vinegar

Buttermilk is a fermented dairy product traditionally produced as the liquid byproduct remaining after churning butter from cultured cream. In modern production, it is typically made by adding lactic acid bacteria cultures to skim or low-fat milk, which ferments the lactose into lactic acid, creating a tangy liquid with a slightly thick consistency and acidic flavor profile. The resulting product has a pH typically between 4.4 and 4.6 and contains lactic acid bacteria beneficial to digestion.

Traditional buttermilk and cultured buttermilk differ slightly in composition and flavor intensity. Traditional buttermilk is thinner and less acidic, while cultured buttermilk—now the commercial standard—is thicker and more sour due to extended fermentation. The ingredient is widely used in baking and cooking throughout North America, Scandinavia, and South Asia.

Buttermilk is a fundamental ingredient in baking, where its acidity reacts with baking soda to produce lift and tender crumb structure in pancakes, biscuits, cakes, and breads. It is also used in marinades and dressings, particularly in Southern American cuisine, where it features in fried chicken, ranch dressing, and coleslaw. In South Asian cuisines, it appears as chaach (a traditional drink) and in chutneys. The acidic nature of buttermilk tenderizes meat, activates leavening agents, and adds subtle tanginess to sauces and dressings.

Common applications include buttermilk pancakes, Irish soda bread, Southern biscuits, buttermilk fried chicken, and various custards and puddings. It pairs well with herbs, garlic, and spices in savory applications.