From our Distiller...Barrel Aging
Last time I wrote about the rise of using oak barrels for the aging of whiskey. This time I’d like to give a little explanation about what is actually going on inside of the barrel to produce the smooth, brown colored whiskey we love today. As I mentioned in my last column there are some characteristics of freshly distilled whiskeys that are less pleasing compared to their aged equivalent, so what is happening? Suffice it to say there is a lot we do not understand about the process, but we do know some things, and slowly but surely research is being done to expand our understanding.
I’ve been having some fun reading scientific articles about what is happening during barrel aging (you can take the scientist out of the lab and put him in a distillery, but he is still a scientist at heart!). As it turns out there is all kinds of fascinating things going on and I’ll try my best to simply explain them. An eye opener for me was that for a lot of the compounds that are less pleasing in fresh distillate, they DO NOT disappear over time, they are still in there! HOWEVER, what happens is these compounds get trapped in little clusters of molecules that are extracted from the barrel. Once trapped, our ability to smell and taste them decreases. The more the barrel-derived compounds get extracted, the more they mask the less-pleasing compounds.
Two of the quicker processes that occur during aging are the extraction of color, and of some flavor compounds (like vanillin – from the breakdown of lignin during charring of the barrel) for the barrel. If you follow popular advertising, there is all kinds of mystique about whiskey moving in and out of the wood, and this is the magic that makes bourbon/whiskey the elegant spirit that it is. To be sure whiskey does move in and out of the wood with changes in temperature, humidity and pressure, but I personally think its importance in aging is a bit overblown. The extraction of the wood is fairly well complete within a year, after that movement into and out of the wood is not so important. More important are the chemical reactions that are occurring between compounds released from the barrel, the ethanol, and other congeners in the distillate. This is what takes the longest time. I suspect most of you have heard about the Angels share which is ethanol that is lost as is slowly seeps through the wood and this adds to the mystique. However, what is more important, (but not terribly sexy sounding) is the movement of oxygen from the air into the barrel where is causes oxidation of compounds in the whiskey – pretty sexy huh? So the whiskey sits while these chemical reactions slowly occur and over time resulting in a smooth final product.
The proverbial question we get asked is when will our aged whiskies be ready? Our standard answer is “when it is ready”. In reality we are looking at early next fall. At this point we will have some 2yr old whiskies which we can legally then label as a “straight” whiskey. In the meantime, we are doing some experiments to improve the aging of our whiskey. Not necessarily to speed up the process, but rather to make whiskey with greater depth of flavor.