Imperial Stout - Champagne Yeast?

My Imperial Stout kid came with a packet of Champagne yeast and instructions to add it when transferring to the secondary to ensure:

a) a drinkable attenuation, and

b) carbonation when bottling.

Two quesitons.

If I take a hydrometer reading when I transfer and the FG is already in the range called for by the receipe is it really necessary to add and will it accomplish the stated goals?

OTOH, is there any reason not to add the additional yeast? Could it change the flavor of the beer somehow?

greenandgold said:

My Imperial Stout kid ...

Click to expand...

I wonder if he was born a brew master?

Seriously, though, the original yeast will probably die of alcohol poisoning long before the beer is "finished." It's possible that they'll be more hearty than expected and the FG will be acceptable, but the more likely result is that you'll have a moderately alcoholic, really sweet stout prior to adding the champagne yeast. Champagne yeast is more tolerant of high alcohol content, so it will ferment long after the original strain dies out, resulting in a drier end product. I recommend following the directions because the champagne yeast will only help your beer get to where it should be. If there are no more fermentable sugars when you add the new yeast, it will just drop out of suspension, having done nothing.

If you want a beer with lower alcohol and higher residual sugar content, then don't add it.

However, I will give you a couple of pointers based on my experience with ultra-high-grav beers:

• Check your gravity before pitching the champagne yeast. I made a barleywine way back when, before I was using a hydrometer. The OG was 1.123 based on ProMash's calcs, so I just assumed that the ale yeast (Nottingham dry yeast) wasn't able to ferment it down all the way. So, I repitched with dry champagne yeast. Nothing happened. The yeast just dropped. By the time I bottled, I was using a hydrometer, and it was actually down to 1.030---12.5% ABV. Not bad for an ale yeast.
• If you do add it, you might think about a starter. It's hard for yeast to get dropped into a high-alcohol environment and just start chugging away.

Thanks for great explanations and answers.

I transferred to the secondary last night and added the Champagne yeast. The SG was 1.032. So far so good since I started around 1.085.

Hopefully I get down closer to 1.020