It's a good question, but much (in a lot of cases maybe most?) of the flavor of a whiskey comes from the cask, not the mash bill, and guaiacol is a component of the wood flavor as well.
That makes sense. But the paper seems to claim that the guaiacol comes from the smoked malted barley:
> Many whiskies, especially those that are made on the Scottish island of Isley, have a typical smoky taste that develops when malted barley is smoked on peat fire. Chemically, the smoky flavour is attributed to phenols, and in particular guaiacol, which is much more common in Scottish whiskies than in American or Irish ones.
I agree that this is where the smoky flavours are supposed to come from. So your question remains unanswered. Perhaps guaiacol is generated from intermediate compounds after distillation? From chemical reactions with the barrel?
Those are all flavors you get when alcohol interacts with charred wood. They're not coming from the bourbon that originally filled the cask, unlike what happens with sherry.
It sounds totally possible. There are a lot of home distillers that age whiskey by putting charred oak pieces in a jar of fresh whiskey. The problem with this process for aging whiskey is that it skips the evaporation that happens through the semi-porous wood and I've heard that the process of the liquid expanding and contracting through the wood also aids in a mellowing of the flavors.
It does mention "It is likely that the concentration of guaiacol in Isley whiskies is even higher.", since Islay whisky often uses peated malt, won't at least some of it be coming from the malt.
As far as I understand, they don't treat the casks differently to other distilleries.
Ironically, it's a little unlikely that Yamazaki barrels are charred. American whiskey is aged in new oak, which is charred or toasted both to standardize quality and also to bring out caramel and vanilla notes from the wood. But single malt scotch is generally aged in used barrels and the barrels are selected in part for the characteristics of what was aged in them before, which is why the "best whiskey in the world" Yamazaki 18 Sherry Cask costs so much. Charring is what you do, in Scotland, to an exhausted cask; it's also something Scotch distillers work to mitigate in ex-bourbon casks.
You have now been subscribed to Barrel Facts. Whiskey barrels are really expensive and the method to make certain types is passed down through generations. The tightness of the barrel and the type of wood are both considered as the wood will expand a bit from absorption of its contents. An amount of whiskey loss is accepted from evaporation of the contents through the porous wood of the barrel. A considerable expertise is necessary to create quality barrels. [1][2][3]
Each type of wood is used for aging different spirits. Oak is most common in whiskey and wine making. Sometimes the barrels are even smoked near a fire to impart a unique flavor into the alcohol that will be held in the barrel. A used barrel is very desirable and can go for higher prices on the open market than even a quality new barrel. This price parity is due to the unique flavor that can be impacted by using a used wine barrel for whiskey, used whiskey barrel for wine, or some other unique alternation of barrel contents.
Barrels that are hundreds of years old, and thick with aged bacteria are used for making traditional Japanese soy sauce. These special family heirloom barrels will be used for many generations before they are eventually retired. [4]
That sounds like malarkey. (Academic) organic chemists love to synthesize compounds that previously could only be done in nature.
Novig is not a chemist, and the recollection is 30 years old. It could be that he misremembered the story, or the original chemist was telling him a tall tale. Instead, this sounds like a just-so story that people tell to impart truthiness.
To be more concrete, what's the compound? As this Wired piece says:
> Much as it sounds, extraction involves the pulling of new chemicals from the oak, including phenol, benzoic acid, and vanillin. When you taste notes of sawed wood, burnt toast, smoke, or vanilla in a whiskey, it’s largely due to extraction of these compounds from the barrel, literally aldehydes and phenols leaching into your drink
> He says the company’s chemists have found about 300 different compounds, and have identified some 200 of them. Once all elements are ascertained and understood, some fear it may be a short step to producing synthetic aged bourbon. “You could go to the lab and say, ‘I’m going to take one part per billion of this and one part per billion of this and three parts per billion of that, I’m going to put it all in a test tube, and I’m going to make the perfect bourbon based on our research,’?” says Brown. He hastens to add, “I don’t think we’ll ever be looking to make a synthetic bourbon.”
Wow that's a massive loss though, I hadn't realised it could be that much lost.
That's also interesting regarding a potential for accelerated ageing.
I'm also wondering how oxygen uptake is effected by differing levels of spirit in the cask, I'm assuming that might effect the taste somewhat.
Edit: The thesis 'Aging of whiskey spirits in barrels of non-traditional volume' has lots of interesting information.
"As evaporation occurs and the fill level decreases, oak not in contact with liquid spirit dries, contracts, and becomes
more porous to the entry of outside air (28). Oxygen present in the barrel fuels oxidation reactions that are essential in the production of mature spirits"
> People have suggested that the inside of barrels were originally burnt to remove the leftover flavors of goods previously stored within, which sounds reasonable enough ... So why do barrel coopers still char the interior? ... Charring the wood actually primes the wood, which impacts the spirit’s flavor in several important ways that have nothing to do with smokiness ... charring essentially opens the wood up, making it easier for bourbon to extract flavors.
"During the aging process, changes in heat and pressure push and pull the alcohol in and out of the wood. There is a constant back-and-forth between aldehyde and acid, until the acids accumulate en masse and turn permanently into esters, adding complex character and deep flavors."
This quote I found interesting. It would seem an important ingredient in making whisky is a locale with reasonably varied weather. I wonder if anyone has tried the equivalent of putting their whisky barrels in a giant iron lung? Pushing and pulling the whisky in and out of the wood more often might speed up the aging process.
"When it opened in 2003, Tuthilltown started experimenting with accelerating the maturation of single malt, rye, and bourbon whiskeys by letting the alcohol settle in 2- to 5-gallon oak barrels, instead of the industry-standard 53- to 55-gallon oak casks, increasing the alcohol-to-barrel-surface ratio. The small barrels sped up aging significantly; we could get to market in months, instead of years,” says Tuthilltown co-owner Ralph Erenzo"
Laphroaig takes 5-year old whisky and then ages it in "quarter casks" (~80 L or 20 gallons) for several months. The result is actually pretty tasty for a relatively cheap scotch. (Warning: must like Islay's or this one will slay you). Their 10-year old bottling is a bit nicer, but almost twice the price.
It's worth noting that more years in the barrel doesn't always improve a whisky. Islay's tend to lose their famous medicinal character if aged for too long, and other scotches often just get musty. I once had a 30-year old bottling of a rye that tasted like licking a steel drum. I'm not sure what went wrong there. Unlike many other things, there isn't so much a point of diminishing returns, but rather, a point after which a whisky will start getting worse, even as the prices continue to grow exponentially.
"Bourbon made in less than a year may be financially savvy, but most bourbon experts say it falls short on taste. “I don’t think new methods are producing whiskey that is comparable,” Bryson says. “Some accelerated whiskeys don’t feel right. They feel too thin; they don’t have the proper ‘roundness.’ ”
I'd have to do a double blind taste-test to be convinced this is true. Are whisky aficionados really more accurate than wine tasters, who famously aren't good at telling what they're drinking at all? I'm certain I could tell an Islay from a Rye or a Speyside, but could I tell a 5-year-old Bourbon from an 8-year-old Bourbon made by the same distiller if they were messing about with these accelerated aging methods?
Aging issues aside, it will be interesting to see how consumer tastes evolve over the coming decades. Scotch has come on big in the last couple of decades and demand for Bourbon is also exploding. Rye (especially Canadian Rye) remains a bit of a niche drink though, but public interest seems to be picking up. Last year, Jim Murray declared the #1 new whisky in the world to be Crown Royal Northern Harvest Rye, which is a good rye for the price, but nothing particularly special. There are several Canadian Rye producers that could easily produce higher end bottlings if the market demand was there, and it does seem to be developing. It would be a fine day indeed if Alberta Premium started regularly producing 20-30 year-old bottlings instead of tricking an extremely limited bottling out every 5 years.
yeah. my point was not that bourbon oozes out the pores of the reused barrel.
my point is that if the oak is the same species as that used in bourbon barrels, and if the barrel is charred in a manner similar to a bourbon barrel then the whisky flavor has a greater tendency toward bourbon-like flavor than if sherry or wine barrels or plain, un-charred oak barrels were used.
bourbon barrel availability to scotch producers increased significantly after 1935 when US federal law required single use bourbon barrels, and, more so later in the 20th century when the supply of Spanish sherry barrels dwindled.
Whiskey is aged in barrels using white oak from North America. The mash is made of grains like corn, barley, rye, etc. I'm guessing the grains came from areas upwind of the plume. Everything pretty much blew out onto the Pacific.
No, it isn't. Scotch whisky can only be aged in barrels that have already been used to age liquor. Conveniently, bourbon must be aged in NEW barrels, so used bourbon barrels are the primary source used for scotch. So, the barrels are sourced for the US and thus not charred with peat.
Other barrels used for scotch are typically fortified wine products, like sherry or port. Occasionally limited releases will be aged in things like ex-rum or ex-brandy casks.
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