Dairy products or milk products, also known as lacticinia, are food products made from milk. The most common dairy animals are cow, water buffalo, nanny goat, and ewe. Dairy products include common grocery store food around the world such as yogurt, cheese, milk and butter. A facility that produces dairy products is known as a dairy. Dairy products are consumed worldwide to varying degrees. Some people avoid some or all dairy products because of lactose intolerance, veganism, or other health reasons or beliefs.
Yogurt is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as yogurt cultures. Fermentation of sugars in the milk by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and characteristic tart flavor. Cow's milk is the milk most commonly used to make yogurt. Milk from water buffalo, goats, ewes, mares, camels, and yaks are also used to produce yogurt. The milk used may be homogenized or not. It may be pasteurized or raw. Each type of milk produces substantially different results.
Buttermilk is a fermented dairy drink. Traditionally, it was the liquid left behind after churning butter out of cultured cream. As most modern butter in western countries is not made with cultured cream but uncultured sweet cream, most modern buttermilk in western countries is cultured separately. It is common in warm climates where unrefrigerated milk sours quickly.
Lactococcus is a genus of lactic acid bacteria that were formerly included in the genus Streptococcus Group N1. They are known as homofermenters meaning that they produce a single product, lactic acid in this case, as the major or only product of glucose fermentation. Their homofermentative character can be altered by adjusting environmental conditions such as pH, glucose concentration, and nutrient limitation. They are gram-positive, catalase-negative, non-motile cocci that are found singly, in pairs, or in chains. The genus contains strains known to grow at or below 7˚C.
Lactococcus lactis is a gram-positive bacterium used extensively in the production of buttermilk and cheese, but has also become famous as the first genetically modified organism to be used alive for the treatment of human disease. L. lactis cells are cocci that group in pairs and short chains, and, depending on growth conditions, appear ovoid with a typical length of 0.5 - 1.5 µm. L. lactis does not produce spores (nonsporulating) and are not motile (nonmotile). They have a homofermentative metabolism, meaning they produce lactic acid from sugars. They've also been reported to produce exclusive L-(+)-lactic acid. However, reported D-(−)-lactic acid can be produced when cultured at low pH. The capability to produce lactic acid is one of the reasons why L. lactis is one of the most important microorganisms in the dairy industry. Based on its history in food fermentation, L. lactis has generally recognized as safe (GRAS) status, with few case reports of it being an opportunistic pathogen.
Filmjölk, also known as fil, is a traditional fermented milk product from Sweden, and a common dairy product within most of the Nordic countries. It is made by fermenting cow's milk with a variety of bacteria from the species Lactococcus lactis and Leuconostoc mesenteroides. The bacteria metabolize lactose, the sugar naturally found in milk, into lactic acid, which means people who are lactose intolerant can tolerate it better than other dairy products. The acid gives filmjölk a sour taste and causes proteins in the milk, mainly casein, to coagulate, thus thickening the final product. The bacteria also produce a limited amount of diacetyl, a compound with a buttery flavor, which gives filmjölk its characteristic taste.
Crème fraîche is a dairy product, a soured cream containing 10–45% butterfat, with a pH of approximately 4.5. It is soured with a bacterial culture. European labeling regulations specify the two ingredients must be cream and bacterial culture. It is served over fruit and baked goods, as well as being added to soups and sauces. It is used in a variety of other recipes. Sour cream is a similar foodstuff, except that crème fraîche is less sour and has a higher fat content. Sour cream may contain thickening agents not permitted in crème fraîche in many jurisdictions.
Skyr is a traditional Icelandic cultured dairy product. It has the consistency of strained yogurt, but a milder flavor. Skyr can be classified as a fresh sour milk cheese, similar to curd cheese consumed like a yogurt in the Baltic states, the Low Countries, Germany and Russia. It has been a part of Icelandic cuisine for centuries.
Viili (Finnish) is a mesophilic fermented milk product found in the Nordic countries, particularly Finland. Viili is similar to yoghurt or kefir, but when left unmixed, its texture is malleable, or "long". The metabolism of the bacteria used in the fermentation also gives viili a slightly different taste.
In food processing, fermentation is the conversion of carbohydrates to alcohol or organic acids using microorganisms—yeasts or bacteria—under anaerobic (oxygen-free) conditions. Fermentation usually implies that the action of microorganisms is desired. The science of fermentation is known as zymology or zymurgy.
Matzoon or matsoni is a fermented milk product of Armenian origin, distributed in Armenia and Georgia. The so-called Caspian Sea yogurt circulated and commercialized in Japan is sometimes said to be the same type of yogurt as matzoon, but a comparison of microbiota and viscosity found that the two are entirely different.
Amasi, maas, or mafi, is a fermented milk product that is similar to cottage cheese or plain yogurt. It is a popular snack in South Africa and Lesotho.
Chal, also shubat or khoormog, is a Turkic and Mongolic beverage of fermented camel milk, sparkling white with a sour flavor, popular in Central Asia — particularly in Kazakhstan, Uzbekistan and Turkmenistan. In Kazakhstan the drink is known as shubat, and is a staple summer food. Due to preparation requirements and perishable nature, chal has proved difficult to export. Agaran is collected from the surface of chal.
Souring is a food preparation technique that causes a physical and chemical change in food by exposing it to an acid. This acid can be added explicitly, or can be produced within the food itself by a microbe, such as Lactobacillus.
Kefir is a fermented milk drink similar to a thin yogurt or ayran that is made from kefir grains, a specific type of mesophilic symbiotic culture. It is prepared by inoculating the milk of cows, goats, or sheep with kefir grains.
Ymer is a Danish soured milk product with 6 percent protein. Compared to standard yogurt, it has a thicker, creamier consistency and a higher protein content. It has a slightly buttery taste and may be very subtly fizzy due to slight carbonation from the lactic fermentation. It was launched commercially in the 1930s. It is made by fermenting whole milk with the bacterial culture Lactococcus lactis.
The term Leben, variously laban, liben, lben in the Middle East and North Africa, refers to a food or beverage of fermented milk. Generally, there are two main products known as leben: in the Levant region and parts of Arabia and North Africa (Maghreb), buttermilk. Leben can be served at breakfast, lunch or dinner.
Curd, also mosaru or dahi or Thayir or Perugu, is a traditional yogurt or fermented milk product, originating from and popular throughout the Indian subcontinent. It is usually prepared from cow's milk, and sometimes buffalo milk or goat milk. The word curd is used in Indian English to refer to homemade yogurt, while the term yogurt refers to the pasteurized commercial variety known as heat-treated fermented milk.
Yayık ayranı, also known as Turkish buttermilk, is a traditional Turkish drink produced from fermented buttermaking by-products, water and salt. It has been traditionally prepared in barrel churns or skin bags. Despite the similar name, it is distinct from ayran. Goat, sheep, or cow's milk can be used for Turkish buttermilk production. Certain acid curd cheeses such as çökelek could also be obtained from yayık ayranı when heated.
