c buttermilk

Buttermilk is a tangy, acidic dairy product that is the liquid byproduct remaining after butter is churned from cream. Traditional buttermilk, made from the whey left after butter production, has a thin consistency and a mild, slightly sour flavor with lactic acid notes. Modern cultured buttermilk, the type most commonly available in commercial markets, is produced by inoculating low-fat or skim milk with lactic acid bacteria cultures (primarily Lactobacillus lactis), which ferment lactose into lactic acid, creating the characteristic tang. This fermentation process takes 8-12 hours and develops a thicker consistency and more pronounced sour flavor than traditional buttermilk.

The term "buttermilk" varies regionally: in North America and Northern Europe, cultured buttermilk predominates and has a smooth, pourable texture with a pH of 4.5 or below. In South Asia and some other regions, traditional liquid buttermilk (called "chaach" or "mattha") remains more common and is thinner and less acidic. Commercial cultured buttermilk typically contains 0.5-2% fat, though whole milk versions exist.

Buttermilk is essential in baking, where its acidity reacts with baking soda to produce carbon dioxide and lift, creating tender crumb structures in pancakes, waffles, biscuits, quick breads, and cakes. The lactic acid also tenderizes gluten strands, resulting in softer, more delicate baked goods. In marinades and brines, buttermilk's acidity and proteins gently tenderize meat and poultry while adding subtle flavor. It appears in dressings (particularly ranch-style dressings), sauces, and soups across numerous cuisines. In South Asian cooking, traditional buttermilk is consumed as a beverage and used in curries and breads. Buttermilk can substitute for milk in many applications when thinned, and is commonly used in batters for fried foods to enhance flavor and texture.