In the 19th century the term “Master Distiller” was used less and the term “Distiller and Yeast-Maker” was more common. The fact is that yeast making was a very important part of the position of running a distillery. Every distillery was using their own jug yeast grown at the distillery. If the distiller could not make a good yeast then he could not make a good whiskey. This is less vital today in a world where you can purchase dry yeast from several different sources, but many of the distilleries today still make their own jug yeast.
Yeast is a very important flavor component to whiskey. There are people who say it only makes up about 5% of the flavor of the whiskey. I personally think this is a low figure and yeast makes a larger contribution than most people think. However even if this 5% figure is correct it is a vital component to the whiskey. Think of it this way – adding salt to a dish is a small part of the overall flavor, but if there is too little or too much it is noticed in the taste. The same can be said for yeast in whiskey – the wrong yeast will be noticed.
Four Roses makes the most of its yeasts and the contribution to flavor from the various yeast strains is noticeable. They have five different yeast strains and two different mash bills thus making ten different whiskeys. Their library of yeast contains many more than the five strains used. The five strains include yeasts that create heavy fruit flavors, light fruit flavors, herbal flavors spicy flavors and floral flavors. Tasting samples from all ten of these whiskeys really shows how much influence the yeast has on the final flavor of the product.
Many distillers claim that it is the rye content that makes a Bourbon Spicy. I never really bought into that story because if it were the rye then rye whiskey should be extremely spicy since it is at least 51% rye. I think the spice in a bourbon comes more from the congeners made by the yeast in fermentation than the rye grain. Brown-Forman makes its own jug yeast for its brands and the strains used for Jack Daniels and Old Forester are known for their fruity contributions, banana in particular. This year’s Old Forester Birthday Bourbon has been described as “banana nut pudding” on the nose. This is, once again, an influence from the yeast.
The wrong yeast can make for a bad Bourbon as well. There are thousands of yeast strains in the world and all are not equal. Some make very good whiskey while others do not. A yeast strain that makes high amounts of wood alcohol is not going to make a drinkable whiskey. The real talent in the 19th century was to be able to collect and grow the type of yeast that does make good whiskey. If you could do that then you could make desirable whiskey. Yes there were other skills that had to be mastered but without a good yeast making a good beer, then your other skills became less important.
This is still true today. I remember attending a talk made by Lincoln Henderson, one of the best distillers of the 20th century in my opinion, and he pointed out that Bourbon had to be made correctly every step of the way and it started with good materials (grains water etc.) and proper fermentation, that included a good yeast. Yeast selection is a vital part of starting your own distilling operation. There are many yeast strains for sale. Most of them are used in beer and wine production. There is even a Texas craft distillery that decided to research the wild yeast found in the area for making their whiskey. They collected dozens of samples and cultivated them into samples large enough to test their fermentation qualities. They finally settled on a strain found in the local pecan groves. I would like to taste their aged spirit and see how that came out.
Yeast is an import subject that needs to be studied in more detail. Does a good Bourbon yeast from Kentucky mutate and change when moved to another part of the country like San Francisco sour dough yeast does? Are there still strains of wild yeast to be found that make good whiskey? Can yeast be altered through mutation that will increase the amount of alcohol and remain true to its taste profile? These are just a few of my questions and the yeast of my worries.
Photos Courtesy of Maggie Kimberl
November 21, 2016 at 11:01 am
Good article and right on. Unfortunately only some of the large distillers have resources to make various breeds of yeast. Once again you pointed out the lack of depth that many of our so called master distillers possess.
November 22, 2016 at 4:59 am
June 26, 2017 at 5:36 pm
This is a good article on one of the most vital and overlooked elements in the bourbon making process. It would be interesting to see a follow up article and interview with Jimmy at Wild Turkey on the value of yeast in producing high quality bourbon.
June 28, 2017 at 1:26 pm
Don, I agree a follow up article should be in the future. I think Al Young should be the one interviewed since his career was spent working with multiple yeast strains.
February 20, 2022 at 4:14 pm
Thanks for the interesting post. After 20 plus year as the Jack Daniel Distillery microbiologist, I hope I have a little perspective to offer on this subject. As you mentioned, the Brown-Forman distilleries propagate and scale-up proprietary yeast cultures on a weekly basis.
Any given yeast culture offers a given POTENTIAL for distillate sensory character. Of course, that potential varies based on fermentation substrate and grain bill. However, achieving that full yeast-driven, sensory potential requires full optimization of yeast conditioning, conversion, and fermentation processes. For this discussion, lets keep distillation effects in a separate bucket.
Typically, yeast character is assessed by analytical GC methods (as well as standard sensory analysis). I’ve seen fusel and congener profiles be suppressed by as much as 50-70% in distillate from a sub-optimized process. I can state with great confidence that if your fermentation pH drops below 4.1, your yeast doesn’t stand a chance of producing close to its full flavor potential.
I’ll add that the commercially available ADY yeast strains typically produce a cleaner, lighter character distillate and are more noteable for yield performance than sensory character.