When it comes to aging bourbon, American oak (Quercus alba) is king. But while American oak barrels account for the vast majority of bourbon aging vessels, their mandatory use is a misconception—federal regulations actually don’t specify American oak when it comes to the virgin containers necessary for bourbon maturation.
“You are legally allowed to use any white oak for bourbon maturation,” says Jarrad Gollihue, PhD, the R&D Master Distiller of Kentucky-based RD1 Spirits.
Since the Bourbon Boom kicked off around 2008, producers have been experimenting with a number of oak species. Sometimes, this is out of necessity due to barrel supply shortage. But more commonly these days, distillers and blenders are trying different oaks in the service of flavor as they seek to bring new profiles to market. The vast majority of these different casks are used for secondary maturation. After an initial aging period, bourbon is transferred to a “secondary” or “finishing” cask that can impart different, sometimes novel flavors to the whiskey.
More and more, bourbon producers seem to be leaning into French oak, a duo of species known as sessile oak and pedunculate oak (Quercus petraea and Quercus robur, respectively) historically important to wine and cognac aging.
“French oak generally is more subtle than American oak; thus, American oak can impart a distinct character to new make corn whiskey, making it suitable for bourbon,” says Gollihue. “This might not be something that French oak could do well if being used for the initial barrel.”
Gollihue—who wrote a dissertation on the influence of wood on whiskey maturation—explains there are a variety of factors that account for the different impacts of American versus French oak, some of which researchers are still working to better understand.
“Essentially, there are two types of whiskey lactone (naturally) found in white oak. Cis is found in higher amounts in American oak, while Trans is generally found in greater amounts in French oak. Humans can taste and smell cis-whiskey lactone more easily.”
“French oak allows for (Oak) toast compounds you can find in American oak without adding additional whiskey lactone notes. This is not because French oak lacks whiskey lactone, but rather because it has a different geometric isomerism ratio that can be perceived differently.”
“American white oak generally [has] higher amounts of beta-carotene, and French oak, specifically sessile oak from Jupilles, [has] greater amounts of lutein. Thus, the Sessile (French oak) would yield flavors more along the lines of floral, sweet, and raisin-like aromas from various Norisoprenoids. While American oak gives us these flavors like rose, apples, and red fruit from the compounds beta-damascenone and beta-ionone.”
Exactly how these differences impact flavor can vary from one whiskey to another. But common themes include floral notes and “rounder,” more noticeable mouthfeels.
“The goal with French oak is to bring out the softer, layered qualities it can impart such as richer vanillas, lighter spice, and rounder mouthfeel,” says Danny Polise, co-founder and blender at Penelope Bourbon. “I noticed awhile back that it allows us to build complexity and elegance into the whiskey without losing the underlying character of the bourbon. For me, it’s about creating a balance.”
Gollihue also cites a variety of flavors that whiskey French oak can impart on bourbon, ranging from chocolate and baking spices to fruity and floral notes unlike what one might taste from American wood.
But crafting American whiskeys with French oak influence takes a deft touch; too much time in the barrel can result in a cloying, overly rich sip.
“French oak can be powerful. It brings strong tannins and structure, so it requires a careful hand,” says Polise. “Too much barrel contact or pairing it with the wrong mashbill, can overwhelm the whiskey and mask its natural sweetness.”
Gollihue agrees the benefits from French oak aging can be a double-edged sword.
“French oak can also provide additional oak tannins, which can be beneficial in achieving mouthfeel balance. Some consumers who are sensitive to tannins may not like the perceived bitterness that can come from French oak.”
Interested in giving French oak-aged bourbon a shot? Below are five of the top expressions on the market, all of which I’ve personally tasted.
Penelope Omega
A relatively new addition to the Penelope Bourbon lineup, this is an 11 year Kentucky bourbon that originates from a 78% corn, 10% rye, and 12% malted barley mash bill. (Meaning it’s likely Heaven Hill distillate.) The whiskey then undergoes secondary maturation for one year in Radoux Omega barrels. The result is a satisfying (but not overpowering) sip that highlights toffee notes alongside a hefty dose of spice. It’s a bit like taking a prototypical Kentucky bourbon, then nudging the profile toward spiced bread pudding—and maybe some Heath Bar toffee as well.
Penelope Omega is bottled at 109.8 proof and carries an MSRP of $129.99.
RD1 Kentucky Straight Bourbon Whiskey Finished With French Oak
The brainchild of Jarrad Gollihue, RD1’s French oak bourbon is aged a minimum of four years and bottled at 101 proof. The French oak influence doesn’t come from recasking the whiskey, but rather via the inclusion of special staves into the existing barrels.
My immediate impression of this whiskey was of an accessible sipper enjoyable in just about every context. It doesn’t make you work too hard to suss out flavors. Instead, it invites the drinker in with traditional bourbon qualities and then layers in some additional dark fruit and dry, tannic oak one would be hard pressed to find via American oak alone.
RD1’s French oak finished bourbon retails for around $65.
Bomberger’s Precision Fine Grain (PFG)
First released in early 2025, Bomberger’s PFG is the newest addition to Michter’s famed lineup of Kentucky whiskeys. And the thrice-honored “World’s Most Admired Whiskey” brand quickly had another hit on their hands. Kentucky straight bourbon was transferred to new French oak barrels, which included customized levels of charring and toasting. (Michter’s specified the barrel staves came from the Tronçais, Allier, Nevers, and Vosges forests.)
The final product is bottled at 100.2 proof. But don’t let that relatively typical proof point fool you. This is BIG whiskey, robust and oak-forward, with sweet, floral tea notes, alongside cherry syrup, cola, and strawberry shortbread. It’s a mighty satisfying drinker, and one to savor over a nice long sipping period.
Bomberger’s PFG isn’t the company’s first foray into French oak aging; indeed, their Shenk’s Sour Mash whiskey has included components aged for periods in the wood. But the expression put this particular aging technique and wood variety front and center, innovating on Michter’s profile and garnering acclaim in the process. Bomberger’s PFG carries a suggested retail price of $140, but expect to see it hovering somewhat higher than that on most retail shelves.
Rabbit Hole Regallier
Louisville-based Rabbit Hole is no stranger to finished woods, though the new Regallier (a Distillery Series release) makes a new experiment accessible with a ~$50 price point and smaller format bottle. Regallier starts with a high-rye, double-malt bourbon mash bill. After initial aging, the whiskey is finished for an unspecified period in French oak barrels. The final result is bottled at a robust 118.9 proof. This one drinks right at its proof and accentuates nutty notes (almond extract and toasted, slivered almonds) to showcase a different side of French oak influence. There’s also plenty of citrus—paritcularly lemon zest—for those who enjoy a touch of tartness to pair with a sweet pour of bourbon.
Barrell Bourbon 12-Year Bourbon Finished in French Oak Casks
This is of my favorite new releases in 2025. Barrell Craft’s 12 year expression may have flown under the radar among some bourbon fanatics—but it’s definitely worth a visit (or two).
Like many Barrell products, this one starts as a custom blend, marrying bourbons from Kentucky, Indiana, Tennessee, and Wyoming. (Due to the age statement, it’s almost certain the final component came from Wyoming Whiskey.) The blend underwent secondary maturation in French oak casts with varying toast levels, which the brand says “imparts a rich tapestry of flavors.”
That’s actually pretty spot on, and each sip brings a lot of creamy spice on the palate—a bit like nutmeg-dusted eggnog, with some lovely tannins that showcase the blend’s impressive age statement.
The bottling clocks in at 108.5 proof and retails for around $160. The one downside is the release size: just 1,500 bottles are available for this particular batch. Let’s hope the brand circles back to it before too long.