Back in 1992, when I was hired full time by United Distillers as their archivist in North America, I was fortunate enough to become involved with the Quality Control Department at the Stitzel-Weller Distillery. That is where I met Mike Wright, the head of Quality Control at Stitzel-Weller. They were running tests on samples from every barrel at Stitzel-Weller. There was a trailer set up and everyday employees were invited in to nose and examine 10 samples of whiskey representing 10 barrels of whiskey aging in the warehouse. This program was led by Mike Wright and the quality control team. Their job was to make sure that no bad whiskey made it into the bottle.

The effort made by this Quality Control team is part of the reason that Stitzel-Weller whiskey enjoys its great reputation. Believe me, there were bad barrels of whiskey that ultimately ended up being sold for re-distillation into alcohol for the fuel industry. Occasionally there were some barrels that had a bad acetate or sulfurous, rotten egg odors and tastes or others that were musty smelling and tasting. Mike Wright was looking for people who could distinguish these odors and I was fairly good at it, but there were many people who were very sensitive to these aromas. Those were the people that Mike wanted to come visit the trailer and help with the survey of barrels. It is the most important part of quality control to catch bad barrels of whiskey before they are bottled.

I asked Mike Wright as to what caused these problems. With musty whiskey, it is usually caused by either grain that has gotten wet and became musty or barrels that have become wet in the warehouse and picked up a moldy, musty odor. The first reason is the responsibility of the Quality Control crew as they test the grain as it is brought to the distillery. They do several tests on samples pulled from the truck delivering the grain. These tests are made before the grain is accepted to be unloaded. The tests include simply smelling the sample, then heating the grain in a microwave and smelling it again. They also test for moisture content. If the grain fails any of these tests, it is rejected. The second cause of must is usually caused by a broken window or a leaky roof in the barrel warehouse. There are some distilleries that are located along a river and get flooded in the warehouses. Those problems can cause musty whiskey.

The other odors and tastes such as sulfur and acetate are usually caused by bacteria infection during fermentation. Once again, Quality Control works hard to detect such infections before it is distilled. If caught early enough, the mash can be treated to prevent problems. These tests are chemical analysis and sensory tests of the fermenting mash. The human nose is often the best tool for detecting these problems and that is one reason I have never met a quality control member that did not have an excellent nose for whiskey.

Even after the whiskey is dumped from the barrel and readied for bottling, the quality control team works hard to match the brand’s flavor profile by blending different barrels together in the batch. These barrels will come from different floors of the same warehouse, different warehouses at the distillery, or in some cases different warehouses from other sites owned by the distillery, and barrels of different ages. Once the flavor profile is achieved, the random bottles will be tested after bottling to make sure nothing happened to contaminate the whiskey during the bottling process. An uncleaned line can mess up many bottles of whiskey in the bottling process.

The next time you enjoy a bottle of your favorite brand of whiskey, think about the work done by the Quality Control staff at the distillery. If it is the flavor profile you expected, and free of off-odors and must, they have done their job correctly. This staff may be dozens of people at a large distillery, or simply one person at the small, artisan distilleries, but they are all heroes who should be respected, for, without them, there would be a lot of bad whiskey put into the bottle.

Photos Courtesy of Michter’s Distillery