As a wine ages, does the alcohol content change?
Answer From Expert Roger Bohmrich MW
The phenomenon of bottle aging is highly complex and is still not fully understood. The wine undergoes chemical changes, and these changes are determined by a myriad of factors: the grape type; production process; pH and sulfur dioxide content; storage conditions (especially temperature); the type of closure and the related oxygen transmission; and the ullage (head space between liquid and closure). One obvious change which can be confirmed visually is that red wines become lighter with age while whites become darker; both eventually take on brownish casts. While older wines often taste "softer" - less acidic - than their younger equivalents, scientists tell us that the acidity does not actually decrease with time. Esters are created from organic acids and alcohols; this might lead to a small decrease in total alcohol content. Empirical studies to analyze wine evolution in bottle are inherently difficult given the enormous variation in wine types and origins, and the fact that bottles must be kept under controlled conditions for many years.
