Fermenting in Hot Climates
TroubleShooting
Bill Mayberry - Cochise County, Arizona asks,
After brewing for a long time in Seattle, Washington I now find myself in extreme southeast Arizona. Seattle was a kitchen brewery but Here I have a shed dedicated to brewing good beer. Last week at 2:30 p.m., the temperature was 96 °F (36 °C) and down to 50 °F (10 °C) at night. Last night was 58 °F (14 °C) and back up to 85 °F (29 °C) at 2:30 p.m. I have a 5-gallon (19-L) batch of California cream ale fermenting. On the advice of a brewer from one of the suppliers, I pitched a cultured batch of turbo yeast high heat at 81 °F (27 °C). The fermentation seems to slow and stops according to the temperature. After two days of robust action it’s settled into an up-down routine. Tomorrow is two weeks and kegging day. My question is, do you have any ideas or thoughts on high heat brewing? My potential alcohol looks like 6.3% as opposed to the 4.3% called for in the recipe and I’m informed that turbo yeast high heat makes a lot of alcohol.
There are a couple of separate issues raised in your question. The first has to do with effectively stabilizing your fermentation temperature to prevent the yo-yo effect you describe. I recently described using water as a temperature buffer to address the very problem you describe, only that in the question I answered the brewer was in a pretty nice climate for brewing … your former home of Seattle. The desert climate is much more volatile and you are clearly seeing a fermentation pattern that really needs to be stabilized to help you produce clean beers that do your brewing shed justice.
The good news is that your average temperature is pretty normal and if you determined the normal temperature over an extended period of time, for example by allowing an insulated water cooler to sit in your shed for a week and measuring the temperature, you probably would find that that temperature is somewhere in the upper 70s °F (~25 °C). Maybe a bit warm for brewing some ales, but certainly not too high for a wide range of beers.
A cheap and easy way to dampen the changes in your fermenter temperatures is to place your fermenter in a plastic trashcan and to drill an overflow near the normal beer level in a full fermenter. The basic method is to fill the trashcan with water and immerse the fermenter. The water acts as a temperature buffer because of its mass (this is one of those times where size really does matter) and relatively high specific heat. In plain terms these properties make bodies of water relatively slow to heat and cool in comparison to something like air. If the normal temperature is not too warm for fermentation, or a few degrees cooler than your target temperature, the only thing that may be required is to fill the trash can up to the overflow level and leave it alone during fermentation.
Chances are that this alone may not work for you in Arizona and that your fermentation will be a little too warm. If this proves to be the case, you can add a water supply line to the bottom of the trashcan and displace some of the warm water. Consider using a needle valve to very slowly and continuously add water or manually turning the water on and off daily as required. This will only work if your ground water is cool enough.
I have never used “Turbo Yeast” but from what I can find online these strains are marketed for fermenting “wash” for distillation. The key traits that these yeast strains have are their tolerance for alcohol, high attenuation rates and rapid fermentation rates. These are not necessarily the things that make for the best brewing strains.
The higher than expected alcohol in your brews is likely due to the high attenuation rate of your chosen strain. But keep in mind that mash temperature really sets the stage for wort fermentability and that it truly takes two to tango when producing high-alcohol beers. If you have poor wort fermentability and a yeast strain that is described as highly attenuative, you may still end up with a high-finish gravity because the wort is simply not very fermentable. If the yeast strain secretes starch-degrading enzymes, like “super attenuators,” things will be different.
My advice about yeast strain is to select yeast strains that produce good beer flavor in the normal temperature range of your brewing shed. For the sake of discussion, assume that your normal temperature is 76 °F (24 °C). With that knowledge in hand, go look for strains that are described for working well at this temperature. You can further refine your search by nailing down the style of beer you want to brew and looking for a strain that works for the style and your temperature norm.