A: Wine’s ability to age and gain complexity with time in the bottle is one of the aspects that makes it different from other things we eat and drink. While all wines have some ability to retain their delicious characteristics for at least a short period of time, not all get better as they get older. Eventually, every wine will get to a point where it is past its prime. For some wines this might be a year or two. For others, it may be decades.
The main structural components in wine (acid, tannin and alcohol) are what help to preserve it so well. They protect against microbiological spoilage and help to slow down oxidation and other forms of deterioration. These components occur in greater or lesser degrees, depending on factors like climate, grape variety and winemaking. For instance, grapes grown in cooler temperatures tend to have higher levels of acidity and make wines that are more age-worthy than similar ones from warm climates. Cabernet Sauvignons have firm tannins that allow them to age longer than many other reds. Adding distilled alcohol to wines, as is the case with the great fortifieds such as port and sherry, can preserve them for several years.
But structure alone is not enough to allow a wine to actually improve with age. A wine must have enough flavour character to balance the high acid, tannin or alcohol. Otherwise, the aromas will fade away over time and leave only structure. As a wine ages, its primary fruity characteristics change to more tertiary ones. For whites, this may take the form of baked apple or toast flavours. Aged reds develop a bouquet laced with coffee, leather and dried fruit. Generally, wines that are defined by their youthful aromatics (think Sauvignon Blanc or Gewürztraminer) are meant to be enjoyed young. Other wines like Burgundy (both white and red) Bordeaux, Barolo and top Napa Valley Cabernet are better when they have a mixture of fruity aromas and complex developed notes.