Sherry wines alcohols

Sherry wines are obtained from young wines, carefully selected soon after completing fermentation. These are typically fortified by adding vinous alcohol until they reach an alcohol content of 15-15.5°. They are subsequently transferred to oak barrels before being aged. In most sherries, wine aging occurs in the so-called solera and criaderas system under the flor film of yeast. Once alcoholic fermentation is finished, races of Saccharomyces cerevisiae that can grow on the surface of the wine switch from fermentative to oxidative (respiratory) metabolism. They spontaneously form a biofilm called flor on the wine surface. 

Plata, M. C., Mauricio, J. C., Millan, C., and Ortega, J. M. (1998). In Vitro activity of alcohol acetyltransferase and esterase in two flor yeast strains during biological aging of sherry wines. J. Ferment. Bioeng. 85, 369-374. 

Shinn s Bitter Wine of Iron. Take of sulphate of cinchona, 6 drachms sulphate of quinia, 2 drachms citrate of iron, 4 ounces citric acid, 1 ounco sherry wine, 4 pints alcohol, 1 pint orange syrop, 1 pint. Dissolve the sulphates and citric acid m 1 pints of hot water, and the citrate of iron in i pint of the same mix the solutions, and add the other ingredients. 

Maturation is conducted in closed, full containers to prevent oxidation and aerobic growth of microorganisms. Etee air contact with low alcohol wine soon leads to vinegar. Except for those sherry types already mentioned, wines ate exposed to air minimally and temporarily. During transfers incident to bulk storage and processing, some air exposure is almost inevitable, mote in total the longer the wine is held. In the cases of white and pink table wines, it is ordinarily as neat zero as possible, and stainless steel or other impermeable containers, inert gas headspace, etc ate employed. Red wines withstand and even benefit from small but repeated exposures to air. 

The enzymes in wine are killed if the percentage of alcohol exceeds about 13 per cent. Fermentation alone cannot make a stronger wine, so spirits are prepared by distilling a wine. Adding brandy to wine makes a fortified wine, such as sherry. 

The Spanish sherry type of film yeasts tolerate high alcohol concentrations (up to 16 percent) and cause compositional and taste changes which are considered to be serious defects in nearly all wines except Spanish-type flor sherries. The most obvious compositional changes in... 

The wine yeast, Saccharomyces fermentati, is able to form a film or veil on the surface of dry white wines of about 15-16% alcohol. This yeast produces agreeable smelling and tasting substances which dissolve in the wine and give it the aroma and flavor characteristic of Spanish fino sherries. To provide itself with energy for growth while in the film form on the surface of the wine, the yeast utilizes some of the oxygen from the atmosphere above the wine in the partially filled butt or barrel to oxidize some of the ethyl alcohol from the wine. The ethyl alcohol of the wine is not completely metabolized to carbon dioxide and water, however, but is oxidized to acetaldehyde—probably the principal compound in the complex mixture responsible for the aroma of this type of appetizer wine. 

Growth of film-forming yeasts is inhibited by ethyl alcohol concentrations higher than about 16 vol %. Fortunately, most of the bacteria and undesirable yeasts which will spoil wines when oxygen is available and which could be a great problem in the production of film wines are inhibited or killed by alcohol levels above 14%. The flor sherry producer thus has a range of about l%-2% ethyl alcohol content in his wines within which it is reasonable to expect film sherry rather than vinegar to result. 

Several botrytized wine specialties, other than Aszu, are also matured in the Tokaj cellars. Traditionally, these were exposed to the air for a short period. Today, this is a characteristic only of dry Szamorodni. During this phase a Saccharomyces film develops spontaneously on the wine s surface. This donates a flor sherry-like character to dry Szamorodni wines (Alkonyi, 2000 Magyar, 2010). The similarity involves only the flor character, since Tokaji Szamorodni never contains added alcohol. Moreover, its acidity and sugar-free extract content is very high and botrytis notes are present in the taste. 

Wine spirits used in shermat production should be low (150 mg/L or less in higher-molecular-weight alcohols), but may contain 100 mg/L or more of aldehydes (or heads) without adversely affecting the quality of the wines. A muscat aroma should be avoided in shermat production. Muscat aroma is characteristically sweet like and flowery and is not compatible with sherry aromas, which tend to be dry and oxidized. 

Fornachon (5) in Australia found that a yeast suspension aerated and agitated in an alcoholic solution produced aldehyde. He reported his extensive research on flor sherry production to the Australian Wine Board (6). 

Organic alcoholic drinks apart from wine and beer make up the minority. Beyond the fair selection of beer, there are smatterings of other drinks that tend to be found in specialist organic retail outlets. These include organic perry, mead, cognac, cider, sherry, port, sake, whisky, cremes and vodka. But as more alcoholic drinks come onto the market, the specialist retailer is able to offer a very comprehensive range to the discerning consumer. 

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