Should I factor out sugar-to-alcohol conversion in stage 2 of a three-wort batch?

Question

I am planning to make a tripel with OG near 1.085. I need to make a strong starter before subjecting yeast to that kind of gravity. I have read that 1.040 is a good gravity for making a starter. So I have the following plan in mind:

1. Cook a 1-gallon first wort with an OG of 1.040. Pitch one Wyeast activator pack.
2. After 24-36 hours, cook 2 more gallons of wort, cool, and add to the first gallon.
3. After another 24-36 hours, cook, cool and add the rest of the wort to a total of 5.5 gallons, with all the remaining fermentables to bring the estimated OG to 1.085 (that's a 1.085 if all fermentables had gone into all 5.5 gallons from the start.)

My question is at stage 2. Regardless of whatever else might be wrong with this plan, should I:

1. be adding 2 gallons of 1.040 wort, being consistent with the 1.040 ideal for starters? Or
2. since I am about to add it to one gallon that has already underwent some fermentation, should I add something more like 2 gallons at 1.050? That will then average out to 3 gallons at 1.040, but with some alcohol content already present?

Which choice leaves me with a healthier yeast count for stage 3? (And if my numbers are off - say I should be staring with stage 1 at only 0.5 gallon instead of 1 - I'd still like to know if in principle I should be factoring out the gravity that has already been fermented away.)

And if there is anything else wrong with this plan, don't hesitate to let me know :) The fermentables are: 11 lb extra light LME, 1 lb specialty grains, 1 lb liquid candi sugar, and 0.5 lb maple sugar, brought up to 5.5 gallons.

Answer 1

You'd need to check the Mr Malty pitching calculator to be sure, but I think you are going way overboard with the starter. For a 1.085 Belgian ale that started off in a smack-pack, I'd make about a half gallon starter of 1.040 gravity and call it a day. I've made a similar Belgian in the past, and did a 1qt starter stepped up with another 2 quarts, and it was waaay more than enough yeast (had a blowoff, it got down to very, very low FG, etc).

Answer 2

The stepwise additions you're making to keep the gravity lower is often done with high gravity brewing. It relieves the yeast from the osmotic stresses of the high gravity wort.

3 stages is probably overkill here. If you want to call the first stage of the brew a starter, that's fine, although you could start with the whole 5.5 gallons at 1.045 and that would be equally fine and cut out a step. When that has fermented down to 1.015 you can add the rest of the sugars and let it ferment out.

If you want to go with 3 stage, then there's no need to try to balance the second addition so that the overall wort hits 1.040. By that point the yeast have propagated to sufficient numbers and acclimatized to the wort. I would wait longer though, 36 hours is probably not long enough. To be sure, take a gravity sample, and start the next stage when the gravity is around 1.015-1.018. This ensures the yeast are still busy fermenting while keeping the gravity reached after the addition low.

Whichever schedule you go for, try to make up your first addition so that it includes all the different sugar types in roughly the same proportion as found in the complete recipe. This helps the yeast keep open the metabolic pathways for the different types of sugar, which will give the highest attenuation.