What's the difference between phenolics in red wines and in a white wine such as riesling ?
Answer From Expert Roger Bohmrich MW
This is an interesting question and calls for a rather technical explanation, so please bear with me. Phenolic compounds can play a significant role in the color, aroma and taste of wine. They are found in far greater concentrations in red wines, yet nonetheless are also present in whites. They are derived from the fruit and can also result from the action of yeasts and wood contact. Phenolic compounds are broadly divided into two groupings. Flavonoids are found mainly in the skins, pips and stems of the grape, although their potential concentration depends on the grape variety. Hence they dominate in red wines which undergo maceration of the juice with skins and woody parts (the pomace) whereas their presence is limited in white wines. This same group encompasses anthocyanins, which give the color to red wines, and flavonoid tannins, providing structure and support. Other flavonoids are flavonols and catechins. The second group, non-flavonoids, takes in compounds such as benzoic acid, benzaldehyde, cinnamic acid and cinnamaldehyde. These elements may give “spice” accents to both red and white wines including almond and vanilla, notably for those wines aged in small oak barrels. The presence of these phenols in Riesling is negligible since, as a rule, this variety tends to be vinified and matured in stainless steel or larger, well-seasoned barrels (as in Alsace or Germany, for example) which impart little to the wine. Understandably, producers do not want to adulterate or camouflage the innate purity and aromatic expression of a fine Riesling.
