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Nov 4, 2018 | WINE

Wine aroma

WINE

Written by torosidiswine

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The appearance, aroma, taste and body of the wine come mainly from four sources:

  • Primary compounds of grape origin, formed in the plant cell.
  • Secondary compounds of grape origin, modified by the applied processes.
  • Compounds, products of alcoholic fermentation formed by yeasts during fermentation.
  • Time-related properties formed during wine maturation (Rapp and Versini 1991).

Alcoholic fermentation represents the main process in which active aromatic compounds are developed since compared to wine the aroma of grape juice/must is relatively low (Rapp 1988, Jackson 2000, Lambrechts and Pretorius 2000). The development of aroma during alcoholic fermentation has not yet been fully elucidated.

Three main pathways for aroma development during fermentation are identified. Some compounds of grape origin remain essentially chemically intact, others are metabolized to give aromatically active metabolites, and others are subject to hydrolysis or biotransformation reactions intracellularly or extracellularly, which modify their aromatic properties.

 

 

 

 

The production, release and modification of volatile aromatic compounds derived from grapes, processes during production, breakdown and modification of non-volatile compounds by yeasts during fermentation play an important role in shaping the aromatic and taste profile of wine (Schreier 1979, Rapp and Mandery 1986, Etievant 1991,  Guth 1997, Lambrechts and Pretorius 2000, Cole and Noble 2003, Smyth et al. 2005).

 

During the yeast growth phase, sugar metabolism leads to the formation of a variety of volatile compounds, including higher alcohols, fatty acids, esters, carbonyl compounds, sulfur compounds and several organic acids, many of which are involved in shaping the aroma and taste of wine (Rapp and Versini 1991, Guth and Sies 2002;  Francis and Newton 2005, Howell et al. 2005, Smyth et al. 2005, Swiegers et al. 2005).

Nitrogenous compounds also contribute to the formation of some of these compounds, especially higher alcohols and esters, and additionally regulate the formation of other volatile compounds, such as hydrogen sulfide, thiols/mercaptans and monoterpenes (Henschke and Jiranek 1993, Rapp and Versini 1996, Albers et al. 1998).

In addition to the production of primary metabolites, yeasts interact with a variety of non-volatile, tasteless precursors, originating in grape, which are of remarkable organoleptic importance. Glycosides and conjugated cysteine, during their hydrolysis by the enzymatic action of yeasts, can significantly contribute to the varietal character of wine (Strauss et al. 1986, Francis et al. 1992, 1996a, b, Sefton et al. 1993, Francis and Newton 2005, Swiegers et al. 2005).

Examples of aromatic compounds originating in grapes are hexayl derivatives that emit aromas of fruits and flowers and some monoterpenes, norisoprenoids (P-damaquinone) and thiols (Etievant 1991, Moio and Etievant 1995, Cole and Noble 2003, Swiegers and Pretorius 2005).

Some phenolic compounds of grapes represent another group of compounds which, interacting with yeasts, modify the organoleptic influence they exert on the characteristics of wine, mainly on color and body (Mazza 1995, Bartowsky et al. 2004, Eglinton et al. 2004, Dillon et al. 2005, Herderich and Smith 2005).

The production, release and modification of volatile aromatic compounds derived from grapes, processes during production, breakdown and modification of non-volatile compounds by yeasts during fermentation play an important role in shaping the aromatic and taste profile of wine (Schreier 1979, Rapp and Mandery 1986, Etievant 1991,  Guth 1997, Lambrechts and Pretorius 2000, Cole and Noble 2003, Smyth et al. 2005).

Thus, any factor affecting the growth and metabolism of yeasts, such as nitrogen, can have an influence on the composition of wine and its organoleptic characteristics.

 

 

Πηγή : Bell S-J and P.A. Henschke , 2005. Implications of nitrogen nutrition for grapes , fermentation and wine. Australian Journal of Grape and Wine Research 11 , 242-295

 

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