We haven’t talked a whole lot about yeast in the past, and, since we’ve resolved to take the training wheels off a bit this year, now seems like a good time to dive in. Just about any home brewer will tell you that yeast is one of, if not THE, most crucial ingredients in his or her batch. Distillers seem rather quieter on the matter, but that could be for a variety of reasons…not the least of which is that distillers seem to be quieter regarding their batches in general. Most of the reading that I’ve done on the subject really focuses on making the cuts and monitoring temperature. I understand why. Monitoring the temperature is the best way to both maximize yield and ensure that you’re not boiling up a big ‘ol jar of poison. However, there seems to be little material regarding ways to improve the taste of the shine. My theory is that this is where yeast can play a pivotal role.
As previously discussed, yeast nutrient has some pretty nasty stuff in it. I understand that the yeast needs it to thrive in a high alcohol environment (most turbo yeasts will push up to 17%). However, there’s nothing to what impact those chemicals do or do not have on the overall flavor. So, let’s talk a little bit about White Labs and what I hope they can do for me.
White Labs is a company that does a lot, and I mean a lot with yeast. It’s safe to say they’re obsessed. If you haven’t had the opportunity you should certainly check out their page: http://www.whitelabs.com/. In addition to stocking brewer’s yeasts they do have a few strains for distillers that should provide both the strong attenuation and high survivability that distillers need. Now, I say “should” because I have not yet tried out their products. You can expect a report once I have.
The good folks at white labs were kind enough to provide the consumer with data regarding attenuation, flocculation, temperature ranges and (you guessed it) alcohol tolerance. Their distiller’s yeast bank in particular has the high tolerance that we’re looking for. Now, I doubt that the high tolerance is 17% like the turbo yeast, but it, allegedly, is good to go until 10-15%.
If you’re unfamiliar with attenuation and flocculation, here’s a brief description.
Attenuation – has to do with how productive the yeast is. It’s calculated throughout the period of fermentation by tracking specific gravity. As the yeast devours the sugar the density of the mash/wash decreases. Tracking the density and running the numbers will let you know how much sugar has been consumed and, therefore, how much booze you have.
[(OG-FG)/(OG-1)] x 100 = attenuation percentage. (yes, I stole that formula from white labs…don’t judge me).
The reason I appreciate White Labs publishing the data is that the home distiller now has a target in mind. We can say BAM the yeast is done. It’s done all it can do according to the manufacturer and we can move ahead to distillation without worrying whether or not the yield will be as high as possible.
Flocculation – It’s a thoroughly disagreeable word. I don’t like the way that it sounds, but that’s not really relevant. Flocculation is all about how successful the yeast is at sinking to the bottom (and out of the way) once the sugar – alcohol conversion is complete. Wild yeasts and many of the bread/brewer’s yeasts don’t really flocculate that well. Since you really don’t want particulates (including flocculated yeast) in your still, knowing what to expect from a flocculation perspective is nice . There’s not (to my knowledge) a more advanced way of measuring flocculation than looking at it and saying, “yep, it’s flocculated”. If I learn otherwise I’ll certainly post something.
The other 2 data points (temp and tolerance) are just nice guidelines. In my opinion, it’s nice to know how warm the mash/wash needs to be kept during fermentation. Understanding tolerance is also great since, well, if we’re talking about a 6 gallon fermenter, 10% is only .6 gallons. It’s a potent .6, but by the time you do your stripping run and cut using the method discussed earlier, you’re left with a pretty sad, lonely little jar. Needless to say, higher tolerance is better. We’ll see what impact the strain has on the taste of the final product.
The Distiller's Journal 