Lactic acid is an organic acid. It has a molecular formula CH3CH(OH)COOH. It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as natural sources. Lactic acid is an alpha-hydroxy acid (AHA) due to the presence of a hydroxyl group adjacent to the carboxyl group. It is used as a synthetic intermediate in many organic synthesis industries and in various biochemical industries. The conjugate base of lactic acid is called lactate. The name of the derived acyl group is lactoyl.
Lactic acid fermentation is a metabolic process by which glucose or other six-carbon sugars are converted into cellular energy and the metabolite lactate, which is lactic acid in solution. It is an anaerobic fermentation reaction that occurs in some bacteria and animal cells, such as muscle cells.
Lactobacillus bulgaricus is one of over 200 published species in the Lactobacillus genome complex (LGC) and is the main bacterium used for the production of yogurt. It also plays a crucial role in the ripening of some cheeses, as well as in other processes involving naturally fermented products. It is defined as homofermentive lactic acid bacteria due to lactic acid being the single end product of its carbohydrate digestion. It is also considered a probiotic.
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.
Probiotics are live microorganisms promoted with claims that they provide health benefits when consumed, generally by improving or restoring the gut microbiota. Probiotics are considered generally safe to consume, but may cause bacteria-host interactions and unwanted side effects in rare cases. There is some evidence that probiotics are beneficial for some conditions, but there is little evidence for many of the health benefits claimed for them.
Filmjölk, also known as fil, is a traditional fermented milk product from Sweden, and a common dairy product within 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.
Malolactic conversion is a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often performed as a secondary fermentation shortly after the end of the primary fermentation, but can sometimes run concurrently with it. The process is standard for most red wine production and common for some white grape varieties such as Chardonnay, where it can impart a "buttery" flavor from diacetyl, a byproduct of the reaction.
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.
Streptococcus bovis is a species of Gram-positive bacteria that in humans is associated with urinary tract infections, endocarditis, sepsis, and colorectal cancer. S. gallolyticus is commonly found in the alimentary tract of cattle, sheep, and other ruminants, and may cause ruminal acidosis or feedlot bloat. It is also associated with spontaneous bacterial peritonitis, a frequent complication occurring in patients affected by cirrhosis. Equivalence with Streptococcus equinus has been contested.
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation, giving them the common name lactic acid bacteria (LAB).
The Lactobacillaceae are a family of lactic acid bacteria. It is the only family in the lactic acid bacteria which includes homofermentative and heterofermentative organisms; in the Lactobacillaceae, the pathway used for hexose fermentation is a genus-specific trait. Lactobacillaceae include the homofermentative lactobacilli Lactobacillus, Holzapfelia, Amylolactobacillus, Bombilactobacillus, Companilactobacillus, Lapidilactobacillus, Agrilactobacillus, Schleiferilactobacillus, Loigolactobacillus, Lacticaseibacillus, Latilactobacillus, Dellaglioa, Liquorilactobacillus, Ligilactobacillus, and Lactiplantibacillus; the heterofermentative lactobacilli Furfurilactobacillus, Paucilactobacillus, Limosilactobacillus, Fructilactobacillus, Acetilactobacillus, Apilactobacillus, Levilactobacillus, Secundilactobacillus, and Lentilactobacillus, which were previously classified in the genus Lactobacillus; and the heterofermentative genera Convivina, Fructobacillus, Leuconostoc, Oenococcus, and Weissella which were previously classified in the Leuconostocaceae.
Leuconostoc mesenteroides is a species of lactic acid bacteria associated with fermentation, under conditions of salinity and low temperatures. In some cases of vegetable and food storage, it was associated with pathogenicity. L. mesenteroides is approximately 0.5-0.7 µm in diameter and has a length of 0.7-1.2 µm, producing small grayish colonies that are typically less than 1.0 mm in diameter. It is facultatively anaerobic, Gram-positive, non-motile, non-sporogenous, and spherical. It often forms lenticular coccoid cells in pairs and chains, however, it can occasionally form short rods with rounded ends in long chains, as its shape can differ depending on what media the species is grown on. L. mesenteroides grows best at 30°C, but can survive in temperatures ranging from 10°C to 30°C. Its optimum pH is 5.5, but can still show growth in pH of 4.5-7.0.
Streptococcus thermophilus formerly known as Streptococcus salivarius subsp. thermophilus is a gram-positive bacterium, and a fermentative facultative anaerobe, of the viridans group. It tests negative for cytochrome, oxidase, and catalase, and positive for alpha-hemolytic activity. It is non-motile and does not form endospores. S. thermophilus is fimbriated.
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.
Fermented milk products or fermented dairy products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been made by fermenting milk with lactic acid bacteria such as Lactobacillus, Lactococcus, and Leuconostoc. The fermentation process increases the shelf life of the product while enhancing its taste and improving the digestibility of its milk. There is evidence that fermented milk products have been produced since around 10,000 BC. A range of different Lactobacilli strains has been grown in laboratories allowing for many cultured milk products with different flavors and characteristics.
Streptococcus equinus is a Gram-positive, nonhemolytic, nonpathogenic, lactic acid bacterium of the genus Streptococcus. It is the principal Streptococcus found in the alimentary canal of a horse, and makes up the majority of the bacterial flora in horse feces. Equivalence with Streptococcus bovis has been contested.
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.
Streptococcus infantarius is a species of bacteria.
Lactobacillus delbrueckii is a species of bacteria in the family Lactobacillaceae. It is part of the microbiota of the lower reproductive tract of women.
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, 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.
