The Lemon Juice In A Whiskey Sour Is More Important Than You Might Think

A delightful mix of tangy lemon, warm-tasting whiskey, and the creamy foam of whipped egg whites — whiskey sours are a staple cocktail, and for good reason. But perhaps the most essential part of a whiskey sour is, well, the sour part. The tart twist in a classic whiskey sour is thanks to lemon juice; which may, on the surface, seem like a humble and unremarkable addition. However, a little lemon juice goes a long way in this signature cocktail, giving a bright twist to whiskey and balancing out the delicious whipped egg whites. So, you'll want to take care when picking the perfect lemons for this drink. 

When making a whiskey sour, you can choose between fresh lemon juice or a pre-bottled variety. And while the pre-bottled lemon juices may seem tempting, you'll want to stick with fresh juice when making your cocktail. Juice from a real lemon will have a fresher (and better) taste than its bottled counterpart, zinging up your whiskey sour more than pre-squeezed juice or sour mix ever could.

Now, not all whiskey sours are built equally. Some home mixologists forgo the egg whites, while others swap in a citrus fruit other than lemons. But you might want to think twice before making shortcuts with your whiskey sour. 

Using prepackaged lemon juice, for example, will result in a mediocre whiskey sour. This is because bottled versions include extra ingredients such as sodium metabisulphite and potassium metabisulphite, which work to preserve the highly perishable citrus juice. These preservatives slightly alter the flavor as well. This, along with the fact that citrus juice (regardless of preservatives) doesn't keep its bright, refreshing taste for very long after squeezing, makes fresh lemon juice the superior choice for whiskey sours.

But there is another juice alternative that might sound tempting to mixologists in the making. Sour mix, a staple on many bar carts, seems like a good choice to use in whiskey sours. After all, "sour" is right in the name. But you might want to hold off on using a sour mix in your whiskey sour. Sour mix is comprised of lemon or lime juice with simple syrup, and — like pre-bottled lemon juice — it doesn't keep its citrus taste as well as fresh lemon juice does. Additionally, the added sweeteners in sour mix can throw off the taste of your cocktail. And no one wants a cloyingly sweet whiskey sour.

Now, just because fresh lemon juice is the best option for your whiskey sour, it doesn't mean that you'll want to squeeze that lemon directly into your cocktail shaker right before serving. Instead, let your lemon juice sit for a few hours before adding it to your cocktail mix. Lemon juice can be a bit too sharp immediately after juicing. This may seem counterintuitive, as you'll naturally want a sour zing to your lemon juice when making a whiskey sour. But if you let it rest for a while, you'll discover the more complex flavors inherent to lemon — which don't fully develop until a few hours after squeezing.

The taste of lemon juice develops over time, thanks to a compound called limonin. Limonin is released when you squeeze lemon juice, and it has a slightly bitter taste. However, limonin doesn't make your lemon juice bitter. Instead, it calms some of the lemon's acidic taste after a few hours. Ideally, you should let your lemon juice sit for anywhere between 4 to 10 hours before use, to ensure the best balance between sourness and more complex flavors. However, if you're short on time, freshly squeezed can work as well; it just won't be quite as mellow as slightly aged lemon juice. So, next time life gives you lemons, squeeze them into your whiskey sour.