Will blending a highly attenuating yeast with a highly alcohol tolerant yeast cleanly lower the final gravity in a very high gravity ale?

I've brewed some ridiculous beers in the past, my highest original gravity resulting in over a final 18% ABV using WLP099 yeast. That particular beer turned out well for how inexperienced I was when I decided to go crazy with that, but I wanted to revisit the idea. My thoughts were to try and brew a crazy, Quadruple IPA (I totally just made that style up, since some commercial breweries have brewed up to whatever they defined as their "Triple IPA"). In order to get anywhere near the distinguishable hop character, I need to get the final gravity low. My intent is to have at least a 15% ABV beer, with well over 100 IBUs, and no higher than a 1.016 final gravity. I'm hopeful that 1.016 is just enough body, that it will assist the hops with masking the alcohol.

The obvious concerns that I should be able to deal with are:

  1. Mash tun capacity
  2. Expenses for all the grain and dextrose
  3. Several aerations throughout primary fermentation
  4. Controlling fermentation temperatures to subdue esters and alcohol burn

What I am uncertain of is how to ensure I get a clean fermentation out of it. What I initially had in mind was to start the fermentation with an adequate dosage of White Labs' San Diego Super yeast (WLP090), of which I'm a huge fan of for clean ale strains. I would pitch a sufficient starter to see the entire fermentation through. According to Mr. Malty, for 6 gallons at 1.130, that's 2 vials at 2.66 liters (using a stir plate). This would ensure that I have at least enough of WLP090 to pull me through should it need to.

The catch is, I'd also blend in any equally sized starter of White Labs' Super High Gravity Ale Yeast (WLP099) approximately 72-96 hours into the fermentation. I figure at this high of a gravity, over-pitching is better than under-pitching, and I can make up for the lost IBUs by throwing more hops at it. I've noticed that the ester profile of WLP099 increases at high gravity, and I want the IPA to be hop forward instead of ester forward. That's why I'd allow the ester-subdued WLP090 handle the majority of the work, and allow the WLP099 finish up what the WLP090 couldn't.

My questions regarding this are, when taking this approach, using a 2 vial/2.66L starter of WLP090 at the start, and another equally sized starter of WLP099 at the 72-96 hour mark, will the ester profile remain subdued, will the beer still ferment low given how the WLP099 will likely out-ferment the WLP090, and are there any complications I haven't outlined above that will throw a wrench in the bucket? Will the lesser alcohol tolerant ale strain cleanly "crap out" when it hits its max or will it throw crazy, unwanted esters? Would I just be better off using one of the two strains? Is the attenuation of WLP099 going to be negatively affected by allowing WLP090 to chew on the wort beforehand? Any advice would be appreciated.

Topic high-gravity yeast fermentation homebrew

Category Mac

1
answered at

I recently brewed a 14% RIS using a similar technique - I started out with S-04, and then used WLP099 to continue where that couldn't. Since the WLP090 yeast strain has a high alcohol tolerance, you only need the WLP099 if you're talking abv levels above around 13%.

I think your plan sounds about right - although I would use more WLP090 and less WLP099, or you risk ester formation due to a large underpitch at the start. (Say 5l of WLP090 and 1l of WLP099 - halve these volumes if stirred.) Pitch the WLP099 when the gravity puts the beer around 7-8%, since the WLP090 might start to slow as the abv raises above 10%. Oxygenate every at 0, 6, 12, 18h hours after pitching, use 2-3x yeast nutrient per normal batch, and rouse the yeast each day after 4-5 days or when the gravity is below 1.060 to ensure good contact with the wort, that will help you get the lowest attenuation. (And naturally mashing very low is necessary too to ensure you have mainly fermentables in the beer.)

You might consider also adding the dextrose after 2-3 to lower the initial gravity.

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