As an expert sommelier and brewer, I can confidently say that whisky can last indefinitely when left unopened. Unlike other alcoholic beverages, such as wine or beer, whisky does not spoil or go bad over time. This is due to its high alcohol content, which acts as a preservative and prevents the growth of bacteria or other harmful microorganisms.
Even if you have an unopened bottle of whisky from several decades ago, it can still be opened and consumed without any concerns. Of course, the taste of the whisky may change slightly over time due to oxidation and evaporation, but this is part of the aging process and is often appreciated by whisky enthusiasts.
Some whisky houses may choose to put a “best by” date on the bottle for formality or marketing purposes. However, this date is usually just a recommendation and not an indication of the whisky's actual expiration. It is more of a suggestion to experience the whisky at its peak flavor profile, as it may start to mellow or develop different characteristics after a certain period.
In my personal experience, I have had the opportunity to taste whiskies from the 1960s and 1970s that were still in excellent condition. The flavors had evolved and matured, offering a unique and memorable drinking experience. It is truly fascinating to see how whisky can withstand the test of time and continue to provide enjoyment even after many years of aging.
It is important to note that once a bottle of whisky is opened, the aging process slows down significantly. This is because the exposure to air can accelerate oxidation and potentially lead to a deterioration in quality over an extended period. However, if the bottle is properly sealed and stored in a cool, dark place, it can still maintain its integrity for several years.
To summarize, whisky can last unopened for an indefinite period of time. While the taste may evolve over time, it does not spoil or go bad like other alcoholic beverages. So, if you happen to come across a vintage bottle of whisky from the '70s or even earlier, don't hesitate to open it and savor the unique flavors and history it holds.