Alcohols higher fermentation

Romani et al. (2011) also evaluated the yeast population dynamics and fermentation kinetics, and their influences on the analytical profiles of Vin Santo obtained at industrial scale utilizing in separate trials two non-Saccharomyces yeasts, T. delbrueckii and Z. bailii. These results were compared with those obtained both with spontaneous fermentation and with an inoculum of a S. cerevisiae yeast strain. The standard kinetics of fermentations were observed in all of the trials, also if a higher fermentation rate was observed in the trials inoculated with S. cerevisiae compared to those inoculated with the two non-Saccharomyces yeasts, and in the spontaneous one. A rapid decrease in non-Saccharomyces yeast was observed in the trials inoculated with S. cerevisiae. In these last ones, after 6 months, 18.4% ethanol was reached versus 16% of the trials inoculated with the non-Saccharomyces strains. No substantial differences were seen for the higher alcohols or other byproducts assayed. 

Due to the concentrating effect of noble rot as well as the maceration widely used before pressing, these wines are rich in polyphenols. They provide more antioxidants than other white wines. This particularly applies to Tokaji Aszu, where maceration occurs in an alcohol medium (fermenting must or young wine). However, the concentration of resver-atrol and its derivatives is not significantly higher than in normal white wines, due to their decomposition by Botrytis oxidases. 

In order to obtain a deep characterization and differentiation of Madeira wines according to main grape varieties (Camara et ah, 2006a,b,c), multivariate analysis was applied to varietal, prefermentative, and fermentative data on terpenoids, Ce alcohols, higher alcohols, fatty acids, ethyl esters, and carbonyl compounds. The results showed that Malvasia wines had the... 

Fusel Oil.—In the first distillation of alcohol from fermented liquids there is always present in the distillate a small amount of the higher alcohols. The mixture of these alcohols which may be separated from the ethyl alcohol is known as fusel oil. It contains some or all of these compounds propanol-i, butanol-i, 2-methyl propanol-i, 2-methyl... 

The higher fermentation temperatures used for whiskey production compared to those used for beer or wine, increase the vaporization rate of organics from the fermenting mash. One distillery had an average ethanol vapor emission rate of 182 g/m of grain processed [50]. Lower average loss rates of ethyl acetate, 0.59g/m, isoamyl alcohol at 0.17g/m, and isobutyl alcohol at 0.051 g/m were also reported, all expressed on the same basis. 

These alcohols and their esters have intense odors that play a role in wine aromas. The main higher fermentation alcohols, components of Fusel oils, are isobutyl (methyl-2-propanol-l) and amyl alcohols (a mixture of methyl-2-butanol-l and methyl-3-butanol-l). At low concentrations (less than 300 mg/1), they contribute to a wine s aromatic complexity. At higher levels, their penetrating odors mask the wine s aromatic finesse. Acetic esters of these alcohols, especially isoamyl acetate, have a banana odor that may play a positive role in the aroma of some young red wines (primeur or nouveau). 

Fermentation is carded out in two different, very distinct ways top fermentation and bottom fermentation. The governing principles are the same in both processes the chief differences are in the type of yeast and temperature employed, and consequently the method used for collecting the yeast after fermentation is finished. The alcohol content and, to a higher degree, the taste and stabiUty of the beer, are directly dependent on the normal progress of the fermentation. 

Yeast (qv) metabolize maltose and glucose sugars via the Embden-Meyerhof pathway to pymvate, and via acetaldehyde to ethanol. AH distiUers yeast strains can be expected to produce 6% (v/v) ethanol from a mash containing 11% (w/v) starch. Ethanol concentration up to 18% can be tolerated by some yeasts. Secondary products (congeners) arise during fermentation and are retained in the distiUation of whiskey. These include aldehydes, esters, and higher alcohols (fusel oHs). NaturaHy occurring lactic acid bacteria may simultaneously ferment within the mash and contribute to the whiskey flavor profile. 

Ethanol [64-17-5] M 46.1, b 78.3 , d 0.79360, d 0.78506, n 1.36139, pK 15.93. Usual impurities of fermentation alcohol are fusel oils (mainly higher alcohols, especially pentanols), aldehydes, esters, ketones and water. With synthetic alcohol, likely impurities are water, aldehydes, aliphatic esters, acetone and diethyl ether. Traces of benzene are present in ethanol that has been dehydrated by azeotropic distillation with benzene. Anhydrous ethanol is very hygroscopic. Water (down to 0.05%) can be detected by formation of a voluminous ppte when aluminium ethoxide in benzene is added to a test portion. Rectified... 

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