What characteristic helps determine if a beer can be aged?

The characteristic that helps determine if a beer can be aged is the alcohol by volume (ABV). Higher ABV beers generally age better than those with lower alcohol content because alcohol acts as a preservative, helping to protect the beer from spoilage over time. Beers with higher ABV can often withstand the changes that occur during aging, leading to complex flavors and aromas that develop over time.

In contrast, hop content, while it can influence the perception of freshness and bitterness in a beer, does not primarily determine aging potential. Beers that rely heavily on hops, such as IPAs, may lose their hop character over time, making them less suitable for aging. The color of the beer, while it can impact the visual experience, does not contribute significantly to its aging characteristics. Foam retention is primarily a quality indicator related to the beer's freshness and carbonation levels, but it has no direct correlation with the aging potential of a beer.