Oak

When aging beer in oak barrels two aspects are occurring: flavor extraction and oxidation.

As regards flavor extraction:

“Below, the major wood flavors at work are addressed.

Lactones, lipids contained within the oak itself, make up a large part of the aroma we associate with oak. In lower concentrations, it strikes the nose as simply “oaky” and pleasantly herbaceous, but higher concentrations can become rose-like, with the highest concentrations giving powerful impressions of coconut. Open air seasoning of oak staves tends to decrease lactone content, but charring of oak can bring this character foreword. As a result, both the seasoning of the wood and the char of the wood will affect its flavor. Balanced with other flavors, lactone character can be highly pleasant, but in excess, many people will find it cloying.

Phenolic aldehydes are derived from lignins, complex polymers that make up part of the oak structure. Phenolic aldehydes, the most important of which is vanillin, are degradation products of lignin, and are formed under the influence of gentle heat or mild acid. Vanillin, of course, gives a vanilla-like flavor, and it is the main ingredient in artificial vanilla food flavorings. The mild heat applied in barrel toasting for wine barrels tends to promote the conversion of lignin compounds to vanillin. Charring, however, while leaving some vanillin intact, can break down lignin compounds to simpler steam volatile phenols, and these are responsible for smoky and medicinal flavors in the wood and any beers later aged in it. Other phenolic compounds include guiacaols (sweet spice, cinnamon) and eugenol (clove).

Hemicelluloses are part of the wood structure, polymers made up of several simple sugars. Upon heating, these compounds degrade into their constituent sugars, which then caramelize into furfurals, maltol, cyclotene, and other compounds that give flavors ranging from bitter almond to toasty, to sweet caramel and burnt sugar. Maltol, which has caramelized flavors reminiscent of freshly baked bread, is also a flavor enhancer and can increase the perception of maltiness in beer. Furfurals, when in contact with active yeasts, can transform from a bitter almond character to smoky, meaty, and leathery flavors that can be desirable in certain aged beers.

Oak tannins are hydrolysable substances that break down into other flavor-active compounds in the presence of beer. While tannins can lend astringency, they are broken down to a large extent by toasting of wine barrels and to a greater extent by bourbon barrel charring. Any previous resident of the barrels is likely to have extracted a large proportion of the tannins, and there is rarely enough left behind to trouble the brewer. Tannins are also powerful antioxidants and therefore provide something of a buffer to the inevitable oxygenation that occurs through porous woods.”

https://beerandbrewing.com/dictionary/h63PzW6oDQ/

And since oak is porous, oxygen will ingress into the beer and oxidation will occur. For most beer styles oxidative compounds (e.g., trans 2 nonenal) are considered a negative but for some bigger/bolder beer styles (e.g., Barleywine, Imperial Stout, etc.) oxidative compounds can be considered to bring positive flavor complexities to the beer.

Cheers!

 

Take a green(live) branch of White Oak (Quercus alba) , scrape the bark, & then taste the layer underneath. Then try an aged piece of (clean ; ) ) wood, maybe freshly split. [No joke]
That'll give you some approximation of what the oak adds to the beer.

 

Such reactions will be dependent on the type of beer and condition of the wood. Brewers might use oak but not necessarily want the oak to add its flavor to the beer. (In the past, many brewers tried very hard to avoid the flavor contributions of wood.)

 

There has been some discussion on the topic of toasting (or charring) the oak. Below is a table detailing how the level of toasting, and the variety of oak, can be impactful to the flavors extracted.



https://ibrewweirdshit.wordpress.com/2017/07/12/no-barrel-no-problem-making-your-own-oak/

Cheers!

 

Cheeky, yes. For a food comparison, when I think I’m tasting tannic qualities, I think of walnuts. Subtle nuttiness with a dry aftertaste as a general profile. Then you can imagine details like English walnut (buttery) vs black walnut (stronger/more bitter). Tastes are different so YMMV.

 

I've had quite a few Oak-Aged Lagers from Modist that does anything from Oak Pilsners, Oktoberfests, & Dark lagers. I've found them all quite enjoyable with a distinguishable earthy, oak, and woodsy quality. Sometimes I think it might kill some other qualities of the beer such as carbonation, but overall I think it adds complexity and a nice earthy and woodsy flavor addition to many lager beers. I love the Oak idea.

 

From the Modist website (with emphasis in bold by me):

“Introducing ModLabs, in collaboration with our good friends Bauhaus, our Oak-Aged Dark Lager brewed with german pilsner, munich malt, crystal and roasted malt. Kettle hopped with Bravo, Saphir, cryo citra & sabro then aged and lagered in our oak foeders.”

https://modistbrewing.com/modlabs/

Were all of the beers you listed lagered in foeders? If so, this will be different from beers aged in oak barrels due to the difference in beer vs. surface area plus barrels are typically only used a handful of times while in contrast foeders are used over and over and over again (i.e., little to no oak flavor contributed after many uses).

Cheers!

 

I didn't read the thread, but I'm going on record saying that oak doesn't "take something" away from the beer, it adds tannins to the beer which give a feel of dryness. It could also be considered astringent, similar to over steeped leaves.

 

Sorry for the misunderstanding. Was not implying that tannins should taste like that in oak aged beers. More of just in general what an overly tannic beer (or wine) can taste like. I’ve tasted A few old school American Imperial/double stouts with this astringent profile due to the heavy use of dark/roast/specialty grain. I’ve even brewed a beer in which I mashed the grains too long and the beer had a slightly unpleasant tannic flavor. Hops can impart unpleasant tannins too.

 

I have a barleywine I brewed at home that I over oaked and it has a similar feel as over steeped black tea. If you're up for an experiment I can send you a bottle if you'd like. The base beer was a b bomb clone and I completely ruined it with wood.