The Collision of Science and Art

Today, we are going to discuss some of the magical things that happen in a whisky barrel. There are a number of unrecordable things that happen inside of a barrel when it is maturing whisky - I say ‘unrecordable’ because scientists have been trying to figure out what exactly happens inside of a barrel for generations, which would open doors for artificial maturation processes and effectively eliminate barrel aging. Luckily for the barrels, many secrets still remain.

In our previous blog post, I posed a question about how aging was discovered and who discovered it. The truth of the matter is that it all came about by accident, and no one person can take credit for it. Alcohol was shipped and stored in oak barrels because there was no alternative, but it soon became apparent that the whisky, wine, brandy, rum, and even beer could be greatly improved depending on the time that it spent in the barrel. And there you have it: the birth of maturing beverage alcohol, and the single biggest influence on a finished whisky, which was discovered completely by accident.

Since its accidental discovery, barrel-aged maturation has become standard practice worldwide. Barrel aging whisky  is a huge expense for a distiller: the cost of barrels, the time required for maturation, and the cost of operating and managing a rick house contribute to these expenses. The cost is somewhat offset by the increased market value of properly aged spirits. Of course, there are tons of fake whisky and fake rums that fake distilleries try to pass off to consumers and avoid the aging requirements.

There are aging laws that dictate the use of common-named spirits. For example, rum has to be aged for two years, and in Canada, whisky has to be aged for three years. These laws are there to protect consumers from fake products that fake distilleries try to pass off to consumers. They also protect real distilleries by making sure that the time, effort, and money that they have invested do not go to waste.

Unfortunately, Saskatchewan is flooded with fake spirits, sold by distilleries using misspelt names to avoid getting caught and being removed from the market; so the next time you see a bottle of spirits with a misspelt description, you will know that it’s not just an honest spelling mistake. Some jurisdictions use the term ‘counterfeit spirits’, but I just call them what they are - fake.

So now that you know a bit about the legal aspect of maturing a spirit in a barrel, we’re going to focus the rest of this blog post on the world of maturing whisky.

Whisky enters a barrel clear of colour and at a higher proof than the finished bottle proof. For example, our bottle proof is 40 percent abv, but our barrel proof is between 53 percent and 55 percent. Why is this important? Well, there is a natural and unavoidable evaporation from a barrel during the aging process, fondly called the “Angels’ Share”. The Angels’ Share can be as high as 20 percent depending on the climate that the whisky is being aged in. Because of this loss, the spirit has to enter the barrel at a higher proof than the desired bottle proof. You can proof down to 40 percent at bottling time, but you can’t proof up (more on that another time).

Why is our barrel proof set at between 53 percent and 55 percent? It’s simple, yet technical: the proof of a spirit within a barrel affects what components are extracted from the barrel and at what rate. This extraction is crucial to reaching the final profile of the final whisky.

Now that we have our new make spirit proofed to the desired abv., into the barrel it goes. The barrel is filled, the bung is hammered in, and the barrel is held in port to watch for leaks. If the barrel has a leak, it must be fixed and not allowed to be removed from port until it is leak-proof. Once it is confirmed leak-proof, it will be transferred to the rick house to begin its ageing process.

It’s time for a fun fact: the term ‘in port’ is a term older than all my sisters combined. A barrel that is held in port is a barrel that has been filled but not allowed to be placed on a ship for shipment until it has proven itself leak-proof. ‘In port’ is a term that we still use, even though we don’t send our barrels off on sailing ships.

So, this is what’s going on from outside the barrel, but it’s what is going on inside that is the magical part. There are roughly three steps of barrel ageing: extraction, maturation, and oxidation and evaporation. Let’s look at the first step.

Extraction is when the alcohol and water mixture extracts components from the barrel. In our case, our mixture is 55 percent abv, so we have 55 percent alcohol and 45 percent water. Water extracts different components from the barrel than alcohol does. This is why the barrel proof of a new make spirit is critical to the profile of the initial spirit. There are an extreme number of different components that are extracted from the barrel which can be roughly grouped as congeners.

Congeners can be described as flavour molecules and atoms. These congeners produce flavours detectable by taste and some detectable by smell. Still others are detected by feel, and let’s not forget the components that we can see - colour. Let me elaborate a bit on that: taste is referred to as character, smell is referred to as nose, feel is referred to as mouth feel, and colour is our visual appearance of the final spirit.

Is this the extent of what goes on in our barrel? No. If it was as simple as that, we would be talking about simply soaking our spirit in some wood so it can sop up what the barrel has to offer.

Another fun fact: some spirits use a process called maceration that is simply soaking a spirit in a fruit or a botanical to extract the goodies out of the specific plant or fruit. Whisky ageing in a barrel is not that simple, which leads us to the next step in barrel ageing: maturation. Scientists cannot fully explain or duplicate this step, which is loosely explained like this:

All of the components that the distiller created in the new make and the components that the new make has extracted from the barrel begin a chemical reaction with each other. Looking at it from the molecular level, you have molecule A that joins with molecule B and forms molecule C. Molecule C is a brand-new compound that is created solely through chemical reactions in the barrel - it is not an original component of the spirit or the barrel. This is how you end up with tasting notes in a spirit like citrus or fruity or grassy even though there is no citrus, or fruit, or lawn clippings in that barrel.

The original molecules and atoms put there by yeast contribution or mash bill or the barrel itself are somewhat predictable. So why can’t science explain and predict maturation? It’s because while A and B make C, molecule A and atom F become V, and V and X and B become W. See what I mean? Well, it gets even more complicated.

Another fun fact: atoms are the smallest form of matter. Multiple atoms make a molecule, and various mixtures of atoms and molecules are compounds.

And while chemical reactions are predictable, there are other factors that affect maturation. For example, the climate in which the barrel is stored is a huge factor. The temperature (hot or cold), moisture level (dry or humid), and even the level of sunlight in the rick house all play a role. There are also environmental considerations: what the barrel was exposed to when it was still a tree. Basically, everything that the spirit and the barrel were exposed to has an impact on the final product. The number of variables is mind-boggling.

The distiller does his best to manage these variables so as to produce a product that is consistent. Sometimes, that doesn’t work and a single barrel is totally different from the one beside it that was filled on the same day. These are sometimes bottled as a single-cask release or might be blended with lots of other barrels to produce a consistent product.

Is that the end? Nope, not quite. There is one more important step.

Oxidation and evaporation is the addition of oxygen into the mix of the molecules and atoms that are present in the barrel. The addition of oxygen creates esterification (the creation of esters - the flavour compounds that gives a whisky complexity and mouth feel, both signature notes of a particular whisky). Evaporation takes place as oxygen and volatile components pass back and forth through the porous barrel.

An oak barrel is liquid-tight; however, wood is a porous material that allows elements to pass through in the form of gas. This is why a barrel isn’t painted or stained, or even covered with wax. Oxygen is a natural and integral part of maturation, and evaporation is the evaporative loss, also called the Angels’ share, another necessary part of maturation. Who would have guessed that a liquid-tight barrel allows gases to pass through it.

There is one more factor that I will touch on that is relatively obvious: time.

Time is very important to the whole maturation process. The magical things that go on inside a barrel take time. As seasons change, so too does what’s happening in the barrel. The summer heat forces the spirit into the pores of the barrel as the contents expand; the cold winter temperatures cause the spirit to be extracted from those pores. This natural pressure change in a barrel could be mimicked by simply increasing and decreasing pressure, but the process would not be made faster as this pressure change would not take into account the time that it takes for atoms and molecules to bond and form new compounds.

When it’s all summed up, there is some real Bill Nye stuff going on in our barrel, all discovered by accident. Imagine that.

-Tim Karchut