Acetobacter fermentation

The sugars in fruits such as grapes are feimented by yeasts to produce wines. In winemaking, lactic acid bacteria convert malic acid into lactic acid in malolactic fermentation in fruits with high acidity. Acetobacter and Gluconobacter oxidise ethanol in wine to acetic acid (vinegar). 

In fermentation for the production of acetic acid, ethyl alcohol is used in an aerobic process. In an ethanol oxidation process, the biocatalyst Acetobacter aceti was used to convert ethanol to acetic acid under aerobic conditions. A continuous fermentation for vinegar production was proposed for utilisation of non-viable A. aceti immobilised on the surface of alginate beads. 

Acetobacter bacteria oxidatively convert wine to vinegar through an aerobic fermentation of ethanol (a primary alcohol) into acetic acid (a carboxylic acid) ... 

L-Iditol (sorbi6rite), the last of the four naturally occurring hexitols, occurs in service berries along with sorbitol. After removing sorbitol from the juice by fermentation to L-sorbose with the sorbose bacterium, Acetobacter xylinum, the n-iditol is crystallized as a benzylidene derivative. It has been prepared by the action of sodium amalgam on... 

Natural aroma chemicals Production via fermentation or enzymatic treatment Oxidation of 2-methylbu-tanol to 2-methylbutyric acid via Acetobacter species... 

Acetic acid is a weak carboxylic acid with a pungent odor that exists as a liquid at room temperature. It was probably the first acid to be produced in large quantities. The name acetic comes from acetum, which is the Latin word for sour and relates to the fact that acetic acid is responsible for the bitter taste of fermented juices. Acetic acid is produced naturally and synthetically in large quantities for industrial purposes. It forms when ubiquitous bacteria of the genera Acetobacter and Clostridium convert alcohols and sugars to acetic acid. Acetobacter, especially Acetobacter aceti, are more efficient acetic acid bacteria and produce much higher concentrations of acetic acid compared to Clostridium. 

Crushing and Fermentation. Daily Equipment Cleaning and Sanitization. All equipment used in the crushing operation must be cleaned and sanitized daily. This is especially important in keeping the local population of fruit flies to a minimum and in avoiding early build up of volatile acidity from Acetobacter infections. Winery waste tends to putrify rapidly if allowed to stand. 

Ethyl acetate is a product of yeasts and a normal component of wine. Its level can be increased by Acetobacter contamination, although most wines showing excess volatile (acetic) acid do not necessarily contain excess ethyl ester initially. It is quite possible to obtain brandy of normal composition and quality by continuous distillation of newly fermented wine containing excess acetic acid, e.g., 0.1%. On the other hand, ethyl acetate can be formed in continuous columns, particularly if the distillation conditions provide for a relatively high ethanol concentration on the feed tray or immediately below. Since acetic acid is weakly yolatile in all mixtures of ethanol and water, it does not appreciably distill upward. Therefore there is no opportunity for acetic acid to combine wtih ethanol in tray liquids normally of high ethanol concentration. 

Whey does not lend itself to direct production of acetic acid by species of the genus Acetobacter. Furthermore, use of combined inocula of yeasts and Acetobacter species has not proved fruitful. However, Haeseler has described an operable procedure, in which an alcoholic followed by an acetic acid fermentation yielded a vinegar with satisfactory qualities (Marth 1974). 

Commercially available ascorbic acid still includes isolation from natural sources, such as rose hips, but large-scale production will involve the microbiological approach, i.e., Acetobacter suboxidans oxidative fermentation of calcium d-gluconate or the chemical approach, i.e.. the oxidation of /-sorbose. 

A number of factors govern the composition of vinegar the nature of the raw material, the substances added to promote alcoholic fermentation and the growth and activity of Acetobacter, the procedure used for the acetification, and finally the aging, stabilization, and bottling operations. 

Various species and many strains of Acetobacter are used in vinegar production. Aeration rates, optimum temperatures and nutrient requirements vary with individual strains. In general, fermentation alcohol substrates require minimal nutrient supplementation while their addition is necessary for distilled alcohol substrates. 

It is probable that the mixture of L-idonic acid (42) and L-gulonic acid (47) obtained from L-xylose by way of cyanohydrins 71 may be directly converted into 28 by fermentative oxidation, as it is known that Pseudomonas aeruginosa371 73-3 and Acetobacter suboxy-... 

D-Gluconic acid (7) is produced at scale by the fermentative oxidation of D-glucose (3) with Acetobacter, Pseudomonas, or Penicillium sp. (Scheme 4.5).33 It is used as a processing aid. 

Methyl-L-sorbose (LXXI)150 was prepared from the corresponding 4-methyl-L-gulitol (3-methyl-D-glucitol) (LXX) by oxidative fermentation with Acetobacter xylinum. The starting material was obtained by hydrogenation of 3-methyl-D-glucose (LXIX). 

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