shaking the fermenter - or - lazy yeast?

surfingpl · 09-08-2008, 09:02 PM

While fermenting, is there any reason why I shouldn't shake my primary fermenter occasionally? I have a batch right now that seems like the yeasties are lazy. After 3 weeks The gravity went from 1061 og to 1030. So I shook it up, and a day later there was activity in the blow off. A week later blow-off activity had pretty much ceased and the gravity was 1021. Yesterday I shook it again and the blow-off had some activity again. Is there anything wrong with rousing the yeast occasionally? This batch is using white labs 550 which is supposed to provide high attenuation.

malkore · 09-08-2008, 10:14 PM

Yes, once fermentation starts, the yeast won't consume oxygen. Shaking up a fermenter could whip oxygen into your beer, oxidizing it, which is not a pleasant flavor.

You will see people recommend rousing certain yeast strains, by GENTLY SWIRLING the fermenter...not 'shaking' it.

Treat it like a baby...you can quietly rock it back and forth, or even stir with a sanitized spoon...but if you shake it, CPS will be all up onz!

surfingpl · 09-08-2008, 10:40 PM

Uh-Oh. I shook the baby. What does oxidized beer taste like? I have heard about it, but never tasted it (as far as I know).

**BigKahuna** · 09-08-2008, 10:43 PM

Quote:

Originally Posted by surfingpl

Uh-Oh. I shook the baby. What does oxidized beer taste like? I have heard about it, but never tasted it (as far as I know).

You'll never forget it once you tast it. It tastes like you're drinking out of a cardboard box. NASTY!

Like Revvy always says...STEP AWAY FROM THE BEER!

if you must do someting while your beer is fermenting....brew another batch.

jds · 09-08-2008, 10:43 PM

I shake fermenters. My belief on the matter is that (1) there's a nice CO2 blanket in the fermenter, resulting from yeast activity, and (2) shaking often evolves CO2 from solution, enhancing the blanketing effect.

Could you mix air in the beer by shaking the fermenter? Probably.
Do I worry about it? Nope.

surfingpl · 09-08-2008, 11:30 PM

Quote:

Originally Posted by jds

I shake fermenters. My belief on the matter is that (1) there's a nice CO2 blanket in the fermenter, resulting from yeast activity, and (2) shaking often evolves CO2 from solution, enhancing the blanketing effect.

Could you mix air in the beer by shaking the fermenter? Probably.
Do I worry about it? Nope.

Well, this makes me feel a little better. I'll be kegging it this weekend so I'll give it a little taste before it goes in the keg. Thanks guys!

T-Hops · 09-09-2008, 12:10 AM

I would also have to agree. After your first 3 - 4 days of fermentation I don't think that there is an oxygen left in the carboy.

**DeathBrewer** · 09-09-2008, 12:15 AM

shaking your beer after primary fermentation is not going to cause any problems, at least not until fermentation is done and all the co2 is out of the carboy, which shouldn't happen anyway, that's what the airlock is for.

it will rouse the yeast and mix everything up, increasing fermentation rate and leaving you with a higher attenuation. i actually highly recommend it when brewing strong ales.

i have a friend that shakes all his carboys continuously for a week after fermentation begins and not once has he experienced oxidation. he's made some of the best beers i've ever tasted and some of them aged years.

i've done it with a few of my beers, too. no problems. no worries.

**Saccharomyces** · 09-09-2008, 04:38 PM

Swirling helps the Belgian strains since they have a tendency to flocculate before they are finished with their meal of delicious wort.

tdavisii · 09-10-2008, 02:04 AM

For my last five or so brews i have shakin the carboy and rowsed the yeast. I think that it helps immencly. The oxygen is already used up. Since there is NO oxygen getting in because of the airlock dont worry about oxidation. As ANDRE 3000 would say "shake it like a poloroid picture"