Aroma And Flavour Analysis

The aroma and flavour profile of a wine is one of the important factor that defines the differences among the vast array of wines and wine styles produced throughout the globe.

The volatile compounds responsible for the aroma and flavour are produced in several stages of wine making. While some volatile aroma compounds arise directly from chemical components of the grapes, many grape-derived compounds are released and/or modified by the action of wine yeast which is Saccharomyces cerevisiae and bacteria, and a further substantial portion of wine flavour substances result from the metabolic activities of these wine microbes (Swiegers et al., 2005). Many biosynthetic pathways in wine yeast and malolactic bacteria are involved in the formation

The most common olfactory contributor to fermentative aroma are esters. This group of compounds is formed mainly as a result of the amino acid metabolism in the grape berry. Primary alcohols that are produced via the Ehrlich pathway subsequently react with acids to form esters. However, they may also originate from grape glycosides (Bell and Henschke, 2005; Swiegers et al., 2005). Volatile acids also contribute to fermentative aroma. Acetic acid which has a distinctive vinegar aroma is by far the foremost component of this group, but medium-chain fatty acids can also be found in wine at low concentrations (Bardi et al., 1999). Another group of compounds that add complexity to the wine aroma are higher alcohols which are also referred as fusel alcohols. The exact role of these compounds is unclear. They can be produced either from amino acids via the Ehrlich pathway or in an anabolic manner from sugars; the latter of these paths is more common in wine (Bell and Henschke, 2005). Carbonyls such as acetaldehyde, with its nutty or cooked fruit aroma, and diacetyl, characterized by a buttery scent, are also produced by yeast metabolism during fermentation. These compounds are intermediates in the formation of higher alcohols (Bell and Henschke, 2005). Several volatile thiols can be beneficial to the typical sensory impression of grape varieties such as Sauvignon blanc, Chenin blanc, Scheurebe etc. and have an overall positive flavour impact on wine. The final category of aroma compounds that yeast commonly produce during fermentation are thiols or volatile sulfur compounds (VSCs) which will be discussed in detail in this