Buttermilk is the liquid left over after producing butter from full-cream milk by the churning process. It has a slightly sour taste. It is quite popular as a coolant in India and a variant called lassi is sold commercially. Many breads are made with buttermilk, and it is also used in creamy soups and sauces. For breads made solely with grains, buttermilk may contain amounts of calcium from its dairy products, such as nonfat dry-milk powder. Butter fabrication in Fügen, Austria Butter is a dairy product made by churning fresh cream. ... Cream is a dairy product that is composed of the higher-fat layer skimmed from the top of raw milk before homogenization. ... A glass of cows milk Milk most often means the nutrient fluid produced by the mammary glands of female mammals. ... Churn is a river that runs through Gloucestershire. ... Human taste sensory organs, called taste buds or gustatory calyculi, and concentrated on the upper surface of the tongue, appear to be receptive to relatively few chemical species as tastes. ... Taste is one of the most common and fundamental of the senses of animals. ... Lassi is a traditional Indian beverage, made by blending yogurt with water, salt, and spices until frothy, that is enjoyed chilled as a hot-weather refreshment. ...

Most of the modern, commercially-available, "buttermilk" in Western supermarkets is not genuine buttermilk but rather cultured buttermilk, that is milk to which souring agents (Streptococci bacteria) have been added to simulate the original product. The sour taste, or tartness of "cultured buttermilk" is owing to the fermentation process, which, if making buttermilk, begins with a commercial product of buttermilk which has become chemically active, or rather fermented. In this reaction the starter bacteria, streptococcus bacteria, turns lactose into lactic acid. As the pH drops in this reaction the milk becomes tart. At this point, casein, a milk protein, precipitates as it is no longer soluble under acidic conditions, causing what is called clabbering. The acidity of buttermilk accounts for its long refrigeration life. This process can be repeated when making sour cream with slight alterations. Exterior appearance of typical American supermarket (a Safeway) Supermarket produce section A supermarket or grocery store is a store that sells a wide variety of food. ... Species S. faecalis S. pneumoniae S. pyogenes S. suis S. viridans Streptococcus is a genus of spherical, Gram-positive bacteria of the phylum Firmicutes. ... Lactose is a disaccharide that makes up around 2-8% of the solids in milk. ... Lactic acid (α-hydroxypropanoic acid, AHA) is a chemical compound that plays a role in several biochemical processes. ... Casein is the predominant phosphoprotein found in fresh milk. ... Sour cream is a dairy product rich in fats obtained by fermenting a regular cream by certain kinds of Lactobacillus bacteria. ...