While there are different types of whiskey (bourbon, rye whiskey, single malt Scotch whisky, Japanese whisky, Irish whiskey, and more), there’s one basic whiskey recipe. The process is much more complex (involving various techniques such as mashing, distilling, aging, and bottling). At its essence, all you need to make whiskey is water, yeast, and a grain (or grains). While all the ingredients are equally important, the grain you use will have the most impact on the overall aroma and flavor.
In my years of writing about alcohol, I’ve spent a lot of time imbibing the various types of whiskey. I’ve seen how certain grains (and their percentages) can impact the nose and palate. In my opinion, the most important additive to enhance aroma and flavor is the grains used (above yeast, water, and other ingredients). Adding or removing certain grains can heavily change the recipe. For example, the addition of wheat can soften your flavor profile, and rye can add some spice.
Some whiskeys are made with only one grain (single malt whisky with barley) or various grains (bourbon with at least 51% corn and other ingredients). While there are other non-traditional grains like millet, quinoa, and more, corn, barley, wheat, and rye are the most commonly used.
The most popular whiskey grains

Now that we’ve learned a little about the importance of the various grains, it’s time to take a deeper dive into the aromas and flavors that each one brings. Below, you’ll find everything you need to know about corn, barley, rye, and wheat.
Corn

When it comes to America’s “native spirit” bourbon, there’s no grain more well-known than corn. To be referred to as a bourbon (among many other rules), the whiskey must be made with a mash bill of at least 51% corn (the other grains will be wheat, rye, barley, or other lesser-known grains).
The use of corn is why bourbon is believed to be sweeter and mellower than other whiskey varieties, thanks to its high starch content. It brings flavors like vanilla, caramel, sweet corn, and butterscotch to the whiskey.
Barley

If you’re a fan of single malt Scotch whisky (or American single malt whiskey), you know all about the appeal of barley. It’s the only grain used in those whiskeys (hence the ‘single malt’ phrase) and a secondary grain in bourbon and other whiskey styles.
Often malted, barley brings flavors like cereal grains, caramel, candied nuts, and chocolate.
Rye

To make rye whiskey, the mash bill must contain at least 51% rye. Rye is also used as a secondary grain in other whiskeys and is known to add a variety of aromas and flavors.
These include notes of herbs, dried fruits, cracked black pepper, white pepper, and a nice hit of warming heat.
Wheat

If you’re a fan of softer, smooth bourbons and other whiskeys, you can thank a high percentage of wheat for that. The use of wheat adds a softness, sweetness, and overall mellow flavor to your favorite whiskey. There’s a reason brands like Maker’s Mark and Old Fitzgerald use a larger percentage of wheat in all of their expressions.