Buttermilk de John Spottiswood

Despite its name and creamy consistency, buttermilk is relatively low in fat. It's sometimes tolerated by people with lactose intolerance since some of the lactose is fermented by bacteria. Most of the buttermilk found in supermarkets is cultured buttermilk, made by adding a bacterial culture to low-fat or nonfat milk. More authentic and tasty, though, is churn buttermilk, which is the liquid that remains after milk is churned into butter. Since recipes often call for just small amounts of buttermilk, many cooks use reconstituted powdered buttermilk.