Alcohols. According to Xxxxxx et al. (2000), the formation of different alcohols takes place at the end of the fermentation, when most of the amino acids have been consumed, whereas, according to Xxxx and Versini (1991), this synthesis occurs at the same time as ethanol production. Ethanol is the most abundant and important alcohol in wine. Ethanol concentration in wine generally ranges from 10-13 mL/100 mL, depending mainly on sugar content and lesser on temperature and yeast strain. Ethanol is crucial to the stability, aging, and sensory properties of wine. It also influences the type and amount of aromatic compounds produced by affecting the metabolic activity of yeast. The dissolving action of ethanol is also probably involved in the reduction of the evaporation of aromatic compounds during fermentation (Xxxxxxxx and Xxxxxx 1981). Moreover, it is also involved in the production of acetals by reacting with the aldehydes. Methanol is also present in wines in fairly large amounts (0.1-0.2 gm/L) (Xxxxxxx 2000). In wines methanol is formed by the degradation of pectic substances, present in crushed grapes, by enzyme action (Ribereau-Gayon et al. 2000). The methanol content in wines is dependent on number of factors like the variety and condition, maceration treatment, fermentation temperature, and pectolytic enzyme treatment. The in vivo oxidation of methanol produces formaldehyde and formic acid which are toxic to the central nervous system. Due to this methanol content is one of the critical control point parameters which should be controlled during the alcoholic fermentation stage to produce wine safe for human consumption (Xxxxxxx and Arvanitoyannis 2001). Other potentially significant higher alcohols in wine are n-propanol, 2-methyl-1- propanol, 2-methyl-1-butanol, and 3-methyl-1-butanol (Xxxx and Xxxxxxx 1986). The higher alcohols are produced as a by-product of yeast fermentation and their concentration is markedly influenced by vinification practices such as temperature, presence of oxygen, suspended solids and yeast strain (Xxxxxxxx 1988). Higher alcohols may produced by deamination of the amino acids and grape-derived aldehydes, and by the denitrification of amino acids (Xxxx 1978). In grape juice and wine, organic acids composition is very important as it highly influences the organoleptic properties, microbiologic control and a parameter of critical control in wine stabilization. The processes like alcoholic fermentation, malolactic fermentation, and oxid...
Alcohols. Alcohols are solvents that dissolve substances such as shellacs, vinyls, acrylics, epoxies and silicones.
