This Stinks! The nose knows...

Or does it? Humans, particularly here in the U.S., are rather bad at analyzing sensory information. Especially smell. This morning, upon arriving at the distillery, I immediately knew that the yeast I had pitched into our latest mash had taken off. Before the door had closed behind me it was obvious that the mash was off to a healthy, fervent fermentation. People regularly comment on how good it smells in the distillery and it does, usually. The everyday smell I hardly even notice anymore, that of oak barrels, grain, aging rum and whiskey wafting in the air. These all smell great, but their constant presence has made me largely numb to them.In my particular field smell is everything. My wife regularly harasses me because I go out of my way to smell things. She laughs anytime I’m handed a plate of food and my first instinct is to stick my nose in and take a deep breath. It just comes with the territory though. (I’ve harassed her back enough about this that she can now tell what I’ve been doing at the distillery that day. I come home from a strip run smelling much different than I do on spirit or mash day.)People often ask how I know where to make my cuts, particularly when running a simple pot still like we have. It’s a combination of information I’m constantly analyzing. Temperature in the still, quantity of alcohol collected, measured proof of spirit all come into play. The biggest factor however, is smell.The final spirit run on our still is the critical point where I ultimately decide the fate of the spirit I’ve spent a couple of weeks producing. As the still is heating up I can handle other tasks and be away from the still. I regularly notice that the run has begun from across the room as I can smell the spirit before it is even coming out of the still. The heart cut, where you separate the good stuff from the funkier elements at the tail end of a run however, needs all my attention. During the phase of the run I pretty much drop everything. I usually try not to have anybody around at this time as I constantly walk away mid conversation every few minutes. Taste doesn’t really serve me here. Smell dictates everything as I repeatedly dip my finger into the streaming spirit and smell. Rub it around on my hands and smell some more. What am I looking for you ask? After doing this for a while I finally zeroed in on a particular smell.Early on I would keep collecting spirit down to bottling strength, sometimes as low as 80 proof. During the run, excited and caught up in the moment, everything seemed great. Then the next day I would taste again and it was always a bit off. Tails, the end of the run, aren’t harmful, but they sure aren’t pleasant. A small amount can add some complexity but too much and you’ve spoiled the batch. The smell isn’t easy to describe, but once you know it it’s very easy to pick out. Wet cardboard comes to mind. Depending on fermentation factors, tails usually show up in a run between 110-130 proof. Obviously there’s still a lot of good ethanol left in the mix. From a business standpoint, this is a huge loss. Luckily, tails can be further distilled to regain most of it. In our runs, once I notice tails starting to show up I make the cut and switch to a different collection vessel. I then continue distilling until there is very little ethanol coming off the still. This second vessel is later distilled in a separate batch. Further distillations yield diminishing quantities until you’ve collected all the ethanol or decided it’s no longer worth the effort. Early on though, by not using my nose efficiently, I greedily collected to much distillate and the juice suffered for it. Smell is everything.Smell can also be deceiving. From perceived sweetness in a spirit to the fear that something may have gone bad. Sometimes these two things are even connected. We proudly talk about bacterial fermentation at 451 Spirits and incorporate it in everything we produce.Bacterial fermentation? Sounds scary you might say. But it shouldn’t be.Yeast is just one type of microorganism used in spirits production. While the yeast is the real workhorse, producing mostly ethanol, it also produces some by products. Bacterial fermentation produces even more of these by products. Without getting too deep into the science of this, essentially, as alcohol is produced, both yeast and bacteria are producing additional acids which then bind with the alcohol to produce esters. These acids, on their own can often smell strange. Ranging from heavy citrus notes to baby vomit or rotten cheese. Doesn’t sound pleasant. But through the magic of chemistry these then bind with ethanol to form notes of sweet cream, coconut or pineapple among many others. Through distillation and further aging these esters bind with other acids and form even longer chains and more complex flavors. All from something you may have been tempted to dump down the drain.So you see, smell is by far a distiller and blender’s most important tool.