Alcohol yeast

Elaboration of the fermentation technology also falls in this period, development accelerated, however, only after World War II. Outstanding results have been attained in the research and application of several other biotransformation procedures as well (e.g., in the transformation of antibiotics). Vitamin B12 production on an industrial scale was first introduced to the world in Hungary. Improvement of yeast strains and their application in the alcohol-, yeast- and wine industries became general practice in the 1960s, together with operation with up-to-date microbial methods for dairy products. Based on results attained abroad, several modern bioprocess plants started operation in the 1970s. 

The process of making dill pickles does not differ much from that of making sauerkraut as far as the fermentation is concerned. The sugars of the cucumbers diffuse out of the cut cucumbers into the liquor and are fermented by lactic acid bacteria and alcoholic yeasts. As in sauerkraut, B. coli communis and allied bacteria are active fermenters producing hydrogen and carbon dioxide. Oidium lactic finally grows on the surface of the liquor and reduces the acidity. 

This reaction is the result of the action of alcoholic yeasts on dextrose sugar. 

Before the acetic acid bacteria are allowed to start their fermentation of the alcoholic solutions, it is important that the yeasts should have nearly completed their alcoholic fermentation as yeasts do not work so well in the presence of acetic acid. This is because of the poisonous effect which acetic acid has on alcoholic yeasts. 

Polysaccharides are mainly extracted from the grapes at the beginning of vatting and partially precipitate in the presence of alcohol. Yeast mannoproteins may be solubilized during postfermentation maceration. 

Meyerhof, O. (1918) Presence of the coenzyme of the alcoholic yeast fennentation in muscular tissue and its significance in the respiratory metabolism. Z. Physiol. Chem. 101, 165-175. 

Pasteur effect Yeast and other cells can break down sugar in the presence of oxygen (eventually to CO2 and H2O) or in its absence (to CO2 and ethanol). The decomposition of sugar is often greater in the absence of oxygen than in its presence, i.e. the Pasteur effect. With oxygen, less toxic products (alcohol) are produced and the breakdown is more efficient in terms of energy production. 

CHjCOCOOH. A colourless liquid with an odour resembling that of ethanoic acid, m.p. 13 C, b.p. 65 C/lOmm. It is an intermediate in the breakdown of sugars to alcohol by yeast. Prepared by distilling tartaric acid with potassium hydrogen sulphate. Tends 10 polymerize to a solid (m.p. 92 C). Oxidized to oxalic acid or ethanoic acid. Reduced to ( + )-Iactic acid. 

Zymase (a mixture) yeast d-glucose, /-fructose alcohol. CO, and small quantities of glycerol 45-6-5... 

Alcoholic Fermentation. Certain types of starchy biomass such as com and high sugar crops are readily converted to ethanol under anaerobic fermentation conditions ia the presence of specific yeasts Saccharomyces cerevisia and other organisms (Fig. 6). However, alcohoHc fermentation of other types of biomass, such as wood and municipal wastes that contain high concentrations of cellulose, can be performed ia high yield only after the ceUulosics are converted to sugar concentrates by acid- or enzyme-catalyzed hydrolysis ... 

Preservatives. Most products must contain preservatives to ensure that yeasts, molds, and bacteria do not thrive in them. These preservatives include alcohol, methylparaben, propylparaben, DMDM hydantoin, diazohdinyl urea, and imidazohdinyl urea. The parabens have limited solubiUty in water, eg, 0.25% for methylparaben and 0.05% for propylparaben (22). If these levels are exceeded in the formula, then the addition of solvents is needed to ensure clear, stable products. 

Metabolic Functions. Zinc is essential for the function of many enzymes, either in the active site, ie, as a nondialyzable component, of numerous metahoenzymes or as a dialyzable activator in various other enzyme systems (91,92). WeU-characterized zinc metahoenzymes are the carboxypeptidases A and B, thermolysin, neutral protease, leucine amino peptidase, carbonic anhydrase, alkaline phosphatase, aldolase (yeast), alcohol... 

Other bacterial strains identified as biodegrading poly(vinyl alcohol) iaclude Flavobacterium (95) 2in.dFicinetobacter (96) and many others, as well as fungi, molds, and yeasts (97). Industrial evaluations at Du Pont (98) and Air Products (99) iadicate that over 90% of poly(vinyl alcohol) entering wastewater treatment plants is removed, and hence no environmental pollution is likely. 

Many other recovery alternatives have been proposed that iaclude ion exchange (qv), pyrolysis, and wet combustion. However, these have not gained general acceptance. A limited number of calcium-based mills are able to utilize their spent pulpiag liquors to produce by-products such as lignosulfates for oil-weU drilling muds, vanillin, yeast, and ethyl alcohol (see PETROLEUM Vanillin). 

Grape and apple juices usually contain all of the trace nutrients required by Saccharomjces for fermentation of sugars to alcohol. Other fmit and diluted honey, as well as barley malt and rice extract, frequendy need additions of nitrogen, phosphoms, and potassium compounds, together with some autolyzed yeast to faciUtate the yeast growth necessary for fermentation. Stimulation oiy4.cetobacter frequendy requires the addition of autolyzed... 

Primitive people very likely encountered vinegar-like Hquids in hoUows in rocks or downed timber into which berries or fmit had fallen. Wild yeasts and bacteria would convert the natural sugars to alcohol and acetic acid. Later, when eady peoples had learned to make wines and beers, they certainly would have found that these Hquids, unprotected from air, would turn to vinegar. One can postulate that such eady vinegars were frequendy sweet, because the fmit sugars would have been acted on simultaneously by both bacteria and yeast. Only since the middle 1800s has it been known that yeast and bacteria are the cause of fermentation and vinegar formation. 

---