Сірке қызықтырғышының биоқабықшасы

Biofilm formed on fermenting alcoholic liquids

Mother of vinegar is a biofilm composed of a form of cellulose, yeast, and bacteria that sometimes develops on fermenting alcoholic liquids during the process that turns alcohol into acetic acid with the help of oxygen from the air and acetic acid bacteria (AAB). It is similar to the symbiotic culture of bacteria and yeast (SCOBY) mostly known from production of kombucha, but develops to a much lesser extent due to lesser availability of yeast, which is often no longer present in wine/cider at this stage, and a different population of bacteria. Mother of vinegar is often added to wine, cider, or other alcoholic liquids to produce vinegar at home, although only the bacteria is required, but historically has also been used in large scale production.

Hermann Boerhaave was one of the first scientists to study vinegar. In the early 1700s, he showed the importance of the mother of vinegar in the acetification process, and how having an increased oxidation surface allowed for better vinegar production. He called the mother a "vegetal substance" or "flower." Martinus Willem Beijerinck, who was a founder of modern microbiology, identified acetic acid bacteria in the mother of vinegar. He named the bacteria Acetobacter aceti in 1898.

The veil is nontoxic and is composed of cellulose and AAB. The raw materials and other manufacturing features determine what genus the bacteria that composes the AAB is from. PCR fingerprinting revealed that Acetobacter genus was the most abundant in mother of vinegar resulting from apples, while Komagataeibacter genus was most dominant in mother of vinegar resulting from grapes. Mother of vinegar from apples had A. okinawenis as the most abundant species of bacteria. Grape vinegar and the mother had K. europaeus as the most dominant bacterial species. There are also many other bacterial genera that are in mother of vinegar. Polymerase Chain Reaction Denaturing Gradient Gel Electrophoresis (PCR DGGE) was used to detect the bacterial components and genera in vinegar. These groups include: Acetobacter, Acidomonas, Ameyamaea, Asaia, Gluconacetobacter, Gluconobacter, Granulibacter, Komagataeibacter, Kozakia, Neoasaia, Saccharibacter, Swaminathania, and Tanticharoenia. These bacteria are normally gram negative or gram variable and have polar flagella. They also need an aerobic environment to grow and prefer an environment with a pH of 5 6.5 but can survive in pH of 3 4. They are non spore forming bacteria. These bacteria are difficult to find in spontaneous fermentation. This is because they are in competition with other microbial groups during the time the mother of vinegar is in the viable but not culturable (VBNC) state. The genera, Gluconacetobacter and Komagataeibacter produce high levels of bacterial cellulose, which is what mother of vinegar is composed of. The amount of Gluconacetobacter and Acetobacter in the mother of vinegar is associated with the concentration of acetic acid in the vinegar. Vinegars with a concentration of acetic acid greater than 6% contained more Gluconacetobacter, while those with a concentration of less than 6% typically see Acetobacter present. However, on an industrial scale, Acetobacter was seen in acetic acid concentrations of 11.5 12%.

Mother of vinegar is also composed of yeasts that ferment the sugars in the wine, cider, or other alcoholic liquids into ethanol. In Shanxi aged vinegar, there was 47 types of yeast found during alcoholic fermentation. However, the three main strains found in the mother of vinegar included, S. cerevisae, P. anomala, and C. berkhout, with S. cerevisae being the most abundant species in the fermentation stage. After the fermentation, S. cerevisiae dominates in growth, due to species having a tolerance to ethanol. Mother of vinegar is also used in the traditional production of balsamic vinegar. Balsamic vinegar is created by cooking down grape juice to create a concentrate. The concentrate is poured into a demijohn and is left to sit throughout the winter. In the spring, the concentrate is transferred to a wooden barrel. By summer, mother of vinegar is used to start the vinegar fermentation. The concentrate and mother are then separated into different barrels of varying wood types. The vinegar is created over the course of 13 years.

Mother of vinegar and mother of kombucha share many similarities, but they are different. Kombucha mother is created from the fermentation of tea, while Mother of vinegar is created from the fermentation of wine, cider, or other alcoholic beverages. The fermentation process of tea creates SCOBY. The SCOBY creates a bacterial cellulose film, like that seen in mother of vinegar. The bacteria also oxidizes the alcohol to create acetic acid. The main bacterial genus involved in the mother of kombucha is Acetobacter, which is also a main genus in mother of vinegar. Kombucha mother also has the bacteria genus Gluconobacter, which is found in some vinegar types. Both vinegar and kombucha mothers contain yeast, which ferments sugars to ethanol. After the fermentation process, the AAB oxidizes the ethanol into acetic acid. The main difference between mother of vinegar and mother of kombucha is the acetic acid tolerance. Vinegar has a higher acetic acid concentration than kombucha, therefore the species in mother of vinegar needs to tolerate higher levels of acetic acid. Due to the differences in the compositions of the mothers, mother of vinegar cannot be used to produce kombucha due to it not being derived from tea and its bacteria having different characteristics.