Whiskey, like all distilled spirits, can have an aggressive, burning sensation when drank. And when we think of this, you might think it must be extremely acidic, similar to that of lemonade or other sour drinks.
But, is whiskey acidic?
The short answer is yes, but this does vary. Since most whiskeys are composed of ethanol (drinkable alcohol) and water, they are pretty neutral on the pH scale, at least initially. However, whiskeys are a product of a fermentation and aging process that does release chemicals with some acidic properties. The addition of other flavoring chemicals can change the acidity of whiskey as well.
Interestingly, whiskey isn’t as acidic as other alcoholic beverages, like beer and wine.
This article will explain what whiskey is, what pH levels are, if acidity level can be changed with decanters and how whiskey and whiskey production correlate with acidic properties.
What is Whiskey?
Whiskey is a liquor or a distilled alcoholic beverage. It is produced by distilling one or several grains that have been fermented into what is called a mash. A mash is a mixture of grains — but in the case of whiskey, it is usually malted barley. A mash can also contain wheat, corn, rye, or other cereals.
The mash is mixed with water and then heated. As some of the grains are malted — or partially germinated, they contain enzymes that break down the starches in the grains into sugars during the heating process.
A substance called wort is the result. Wort contains sugars like maltose — which can be fermented with the addition of brewer’s yeast. Ethanol is a by-product of fermentation. The resulting fermented, somewhat alcoholic liquid is called the wash.
It is from the wash that distillation can begin. In short, the alcohol in the wash is boiled off and condensed back into a liquid, collected, and stored in wooden barrels. The liquid is aged in the barrels — which are usually made of American or French oak wood — for a period of two years or longer.
After this period, the resulting liquid can be considered whiskey — but it can also be further blended with other distilled whiskeys, or have other flavorings added.
Recommended reading: Will bourbon barrels rot (and tips on how to keep them preserved).
What is an Acid?
An acid is a molecule, or collection of molecules, or ions that contain atoms that can give off positively charged subatomic particles (protons) like hydrogen ions (H+) or form covalent bonds with pairs of other electrons. Acids react differently to other substances, sometimes resulting in corrosive reactions.
Acidity in water-soluble substances is measured on the pH (‘potential of hydrogen’) scale. On a scale from 0 to 14, substances are deemed either acidic (when the pH is under 7) or basic (when the pH is over 7).
Basic, or alkaline substances, are those that form hydroxide ions (OH-) in water and react with acidic substances.
For reference, purified water is considered neutral, with a pH level of 7.
So the lower the pH level of a substance (if it is below 7), the more acidic it is. A higher pH level above 7 makes the liquid basic (or alkaline).
Is Whiskey Acidic or Basic?
Since whiskey is initially comprised mostly of water and ethanol, it would seem like it is not acidic — at least to start. Water has a pH level of 7, while ethanol has a slightly basic pH level of 7.33.
But this is misleading — because that would mean the whiskey is a pure mixture of water and ethanol (it isn’t). Malted barley, for example, is more likely to have a lower pH level at around 5.6, while barley mash has an even lower pH at 5 to 5.5.
In fact, a 1942 study of 108 barrels of Bourbon and rye whiskey found that before it was aged, whiskey had pH levels ranging from 4.4 to 5.1.
The acidity level seemed only to increase as the whiskey aged. The study found that after 12 months, the pH levels dropped to a range of 4.1 to 4.55. After 48 months, the pH levels dropped to a range of 4.0 to 4.45.
These pH levels suggest that whiskey, once aged, is indeed acidic. It is slightly more acidic than black coffee (4.85 – 5.1 pH) but less acidic than orange (3.5 pH) or lemon (2 pH) juices. Flavorings added to whiskey can also change the pH level.
Does keeping whiskey in the bottle for long periods make it more acidic?
After whiskey is made, it is aged in oak barrels. In the case of bourbon, it is new, charred oak barrels. The whiskey is kept for different amounts of time, some just a few years, while others can be decades.
But once the whiskey is bottled, the aging process stops. There is some debate on how much of the flavor changes over time, in both an unopened bottle and an opened one.
Are certain whiskeys more acidic than others?
There are subtle differences in the acidity levels of specific brands of whiskey. Here’s a quick rundown of a few popular whiskeys:
- Glenfiddich Scotch Whisky 21 year – 3.64
- Chivas Regal 12 year – 4.05
- Jack Daniel’s Black Label – 3.89
- Bowmore 15 year – 3.94
For the most part, the range of pH levels, specifically how acidic whiskey is, doesn’t differ dramatically between brands or the age of whiskeys.
Can a whiskey decanter change acidity or flavor?
Decanters are used mainly for wines to let the beverage breathe and separate any sediment. This process can let out some of the aromas of the wine, while also changing the flavor profile of the drink.
However, decanters can also be used for whiskey. If you’ve seen shows like Mad Men or other shows set in the 1960s, it is pretty common to see a bar table filled with a bunch of different decanters filled with whiskey.
But decanters don’t really change the flavor profile in whiskeys. While the whiskey may breathe a little, it really won’t taste any different than from straight out of the bottle.
So while a whiskey decanter may not necessarily affect its taste, it definitely looks cool and can impress your guests when they see a beautiful decanter holding your caramel-colored bourbon.
If you’re into buying a whiskey decanter to hold your distilled spirit, check out Vintage Gentlemen and their collection of whiskey decanters. Here are some recommended decanters.
What about other alcohols, like beer and wine?
Beer and wines are actually more acidic than whiskey. Beer is acidic because of the fermentation process as well as the addition of yeast, sugars, and wheat. Wheat itself causes the most acidity in the beer. Wine also has sugar and yeast, which make it acidic. Essentially, it’s the sugar that increases the acidity level.
The pH level of lagers is between 4.0 to 5.0, while ales are between 3.0 to 6.0. Some Belgium beers have a pH of 3.5.
White wines that are sweet have a pH of about 3.0. Light-bodied whites have a pH of 3.1, while other white and red wines have a pH of 3.5. Other reds can run around 3.8.
The Final Round
So in summary, whiskey is somewhat acidic, but not as acidic as other alcohols like beer and wine. This acidity level in whiskey can increase during the aging process and can be made more acidic by other factors, such as the addition of flavorings and coloring.
Whiskeys that are aged longer tend to have a smoother profile, but may not necessarily be less acidic.
Check out this next article to learn about bourbon barrels and their cool uses!