When it comes to the perfect drink, all sorts of things need to come together. A good drink is dependent on the quality of the product, the alcohol content, the company and ambience of where you are drinking, and the correct receptacle, whether a tumbler or fancy engraved glass. However, perhaps one of the most misunderstood and yet important aspect for making a good drink is the aroma.
Smells are highly important for our sense of taste. In fact, while we can identify over 20,000 different odors in varying intensities, our taste buds can only detect five primary tastes, which are sweet, bitter, sour, salty, and umami (a savory, meaty flavor). When we drink, our nostrils pick up the aroma, which when combined with what our taste buds are sensing, determines the intensity of flavor. This is known as the retronasal effect and is the reason why food and drink becomes tasteless when we have a cold – it’s not our sense of taste becomes diminished, but we lose our sense of smell, resulting in food and drink becoming bland.
Both aroma and alcohol are molecular. That is to say, when we smell something our noses are actually sensing the aroma molecules as they evaporate into the air and make their way into our noses. Aroma and alcohol molecules are very similar to each other and tend to cling together, so the more alcoholic a drink, the more aroma molecules it can contain. Scientists classify aromas into different categories, and each category of aroma reacts differently with alcohol molecules and with other aroma molecules. These categories are:
- Acids —have a pungent sour smell that disappears when they react with alcohol and becomes sweeter and fruitier.
- Aldehydes —have similarities to both acids and alcohols and reacts easily with both.
- Esters —are a combination of an alcohol molecule and an acid molecule, and they generate a tart flavor.
- Ketones —that have a subtle aroma and are highly soluble in water and also bond easily with other molecules.
- Iones —produce fruit and berry flavors.
- Lactones —the acids found in milk, which contribute to the flavor of cream and butter.
- Phenols —account for many of the aromas of spices and herbs.
- Pyrazines —bond easily with alcohol and acids and provide the flavor of roasted nuts and chocolate.
- Sulfur compounds —give an acidic flavor, although they can be unpleasant in large quantities.
- Terpenes—are highly volatile and give a fruity aroma
Alcohol molecules also have aromas, usually generated by the fermenting process, and are often floral or fruity. Different alcohol and aroma molecules have varying molecular weights. Aromas with lower molecular weights are more very flavorful and volatile than those with heavier molecular weights. These lighter aroma molecules are also more likely to cling to alcohol, while those heavier aroma molecules tend to have subtler flavors and evaporate more readily.
This is why drinks with high alcohol contents often have subtler tastes, because only the heavier, subtler molecules are evaporating and the lighter, more volatile aroma molecules are clinging to the alcohol. Therefore, the more alcoholic the drink, the less pungent the smell. This is true of spirits such as whiskey, brandy and vodka, in which the flavors of the drink are often masked by the overwhelming taste of the alcohol. It is also why lower proof cocktails are far more aromatic than stiff drinks such as martinis and Manhattans.
Releasing the Flavor
Because the strong, more volatile aroma molecules cling to the alcohol in a drink, the key to enriching the flavor is in releasing all these lighter but more fragrant molecules for our noses to sense. And the secret to this, which is something every good bartender will tell you, is to add water.
When you add water, effectively you are weakening the alcohol content, which allows the lighter and stronger aroma molecules to separate from the alcohol molecules and evaporate more easily. This results in a stronger smell, and because aroma is so important for tasting drinks, helps intensify the flavor. The more water you add, the stronger the aroma and the more flavorsome the drink. This is why spirits such as whiskey taste so much better when poured onto ice, as the ice helps free the aroma molecules from their alcohol bonds and increase the flavor in the drink.