Role in wine flavor

The products of yeast autolysis, such as amino acids may also play a role in wine flavor. The autolysate by-products may also serve as substrates for secondary fermentations. Malic and tartaric acids, the principle organic acids in grape must and wine, can also serve as substrates for secondary fermentation. 

Because they are important, the phenolics and their roles in wine have been studied considerably (I), but more needs to be known. Since different classes of phenols behave quite differently in the various roles as pigments, oxidation substrates, flavors, etc., separate consideration and analysis is essential to completely understand them. Every individual phenol should be separately determined precisely and quantitatively. Chromatography may solve these problems, but for now, chromatography and other detailed separatory methods have drawbacks, particularly for economical application to many individual wine or grape samples. 

Regardless of the rather pervasive opinions regarding yeast strain effects on wine flavor, the data accumulated over the past half century clearly demonstrate that these opinions are, in actuality, misconceptions regarding yeast s role in wine fermentations, at least with regards to Saccharomyces cerevisiae. The myths may be debunked as follows ... 

Phenolic compounds play a vital role in the flavor of red wines. They are responsible for some positive tasting characteristics, but also for some rather unpleasant, negative aspects. Body, backbone, structure, fullness and roundness are all organoleptic qualities characteristic of great red wines. On the other hand, bitterness, roughness, harshness, astringency and thinness are faults that must be avoided as they are incompatible with quality. 

These molecules include sulfur amino acids, which play an essential role in sunlight flavor . This phenomenon is directly linked to the appearance of methanethiol and dimethyldisulfide in wines exposed to light, which give them cooked cauliflower or wet wool smells. 

The organic acids of Wines play an important role in their flavor, color, and keeping quality. Three are derived from the grape tartaric. 

In this review an original and unique approach was undertaken to unite the notions "heterocycles" and "wine principles." Indeed, it is astonishing that natural wines contain numerous heterocyclic principles in varying quantities (as low as nanograms ) that contribute to flavor, smell, taste, and aftertaste ("finish") sensations, all of which are characteristic of the different grape types. During aging and maturation of the wines in barrels and bottles, manifold additional heterocycles are formed or extracted. The odor threshold plays an important role in all cases, which is ultimately dependent on the chirality centers of the isomers involved in aroma. 

As this brief excursion into the world of wine principles demonstrates, there are manifold heterocycles that have been detected, isolated, and characterized. Many of them play a decisive role for taste, flavor, smell, and color of wine others play a significant beneficial role to the human health. Due to their antioxidant activity these latter components display cardioprotective abilities and are chemopreventive in antitumor and anticancer activities. Heterocycles are one class of compounds in a much... 

The infusion of spices and herbs not only gives vermouth its unique flavor and aroma but also imparts medicinal properties. Some of the benefits ascribed to vermouth are given in Table 8.1. Feher and Lugasi (2004) compared the antioxidant characteristics of young vermouth with three red, three white, and one rose wine. Consumption of one unit (100 mL) of vermouth provided 220 mg polyphenolics, whereas wine in the same quantity was reported to have 35 mg. Polyphenolic compounds are reported to play a substantial role in protection against oxidative stress. 

Therefore, volatile phenols play a minor role in the aroma of most wines, and when their influence is significant in certain wines, they have mostly a negative effect, which can definitely depreciate their aroma in limit cases (phenolic off-flavors). Thus, the corresponding precursors in grape, phenolic acids, as well as the above-mentioned unsaturated lipids, are hardly taken into account to capture an essential characteristic of the varietal aroma, but to avoid their transformation into off-flavors. 

Sulfur compounds occur naturally in wines in very low concentrations, but play an important role in the determination of the flavor and aroma of the wine. 

At last the sensory part of ethanol in wine is important, it plays a major role on the volatility of flavors and in the interactions between aroma compounds and other components. 

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