As an expert sommelier and brewer, I can assure you that bourbon does indeed lose flavor after opening. This is due to the interaction between the whiskey and the oxygen in the air. When a bottle of bourbon is sealed, it is protected from oxygen and the flavors are preserved. However, once the bottle is opened, the whiskey is exposed to oxygen and this can lead to changes in taste.
Oxygen can cause the whiskey to oxidize, which can result in a loss of flavor and aroma. The longer the bourbon is exposed to oxygen, the more pronounced these changes can become. This is why it is important to consume your bourbon within a reasonable amount of time after opening.
To minimize the loss of flavor, it is crucial to store your opened bottle of bourbon properly. The best way to do this is to keep it in a cool, dark place such as a cabinet or pantry. Heat and light can accelerate the oxidation process, so it is important to avoid storing your bourbon in direct sunlight or in a warm area.
Another important factor in preserving the flavor of your bourbon is to ensure that the bottle is sealed tightly. This will help to minimize the amount of oxygen that comes into contact with the whiskey. Make sure the cap or cork is securely in place after each use, and consider using a bottle stopper or vacuum sealer to create an even tighter seal.
It is also worth noting that the type of bourbon can play a role in how quickly it loses flavor after opening. Higher proof bourbons tend to have a longer shelf life once opened, as the higher alcohol content can help to slow down the oxidation process. Conversely, lower proof bourbons may be more susceptible to flavor loss over time.
In my personal experience, I have noticed that bourbon can start to lose some of its complexity and depth of flavor after a few months of being opened. The initial bright and vibrant notes can become muted, and the overall character of the whiskey can change. While it may still be enjoyable to drink, it may not have the same impact as when it was first opened.
To summarize, bourbon does lose flavor after opening due to oxidation. To minimize this loss, store your opened bottle in a cool, dark place and ensure it is tightly sealed. It is also important to consume your bourbon within a reasonable amount of time to fully enjoy its flavors.