Dead Yeast

[chefbri]

I started brewing a porter a few weeks ago. It started out fine. I had to go out of town for a week, during that time our AC went out. The brew had been at about 85+ degrees for a week. From what I can tell the yeast is dead. It has remained at 1.028 from a 1.045 since I have been home. I have syphoned the wort into a second fermenter to get it away from the dead yeast. Is it worth adding a fresh yeast starter to finish the fermentation or is it shot?

 

[smagee]

Yeast doesn't typically die anywhere lower than 110F or so, depending on the strain and such. Sounds like you have a stuck fermentation; re-pitching a starter could help, so that'd probably be the proper first step. Don't give up yet .

 

[jlaureanti]

How do you aerate? what was your mash temp? Stuck fermentations can be easily attributed to an improper oxygenation level (or the O2 level was too high, probably not the case though). If your conditions were optimal for your yeast buddies they would have done their job at 85+ and you would be left with a very dry, fusel-y beer.

I'd repitch and shake and the **** of your fermenter. be ready to crash cool to stop fermentation before those yeast eat all the sugars and take your beer outside of the style guidlines you are looking for

 

[COLObrewer]

How do you aerate? what was your mash temp? Stuck fermentations can be easily attributed to an improper oxygenation level (or the O2 level was too high, probably not the case though). If your conditions were optimal for your yeast buddies they would have done their job at 85+ and you would be left with a very dry, fusel-y beer.

I'd repitch and shake and the **** of your fermenter. be ready to crash cool to stop fermentation before those yeast eat all the sugars and take your beer outside of the style guidlines you are looking for

+1, I would think if anything the 85F temperature should have made your yeast go into gluttonous and frenzied consumption phase eating all sugar in sight, unless they had no oxygen, then they couldn't breath (or some other factor that stressed the yeast early on)

 

[chefbri]

I aerated with a fish tank air pump and let it run for about 30 minutes. I pitched an active yeast starter at 78 degrees. I initially thought that it was a stuck fermentation, so I stirred the settled yeast back into suspension. It resulted in minimal air lock activity, but the gravity remains the same. This led me to believe that the yeast was dead. I started a fresh yeast starter and I'm going to re-pitch.

 

[chefbri]

If I'm going to re-pitch a yeast starter, should I aerate the wort again?

 

[onthekeg]

Don't aereate now, that will oxidise the beer.

 

[Revvy]

Yeast doesn't just "die" unless you dump it into boiling water.

I take it you think something's wrong because of your airlock right? Your airlock means nothing.....You don't really know if fermentation has stopped or not, just that your airlock has.

Airlock bubbling means nothing.

A beer may ferment perfectly fine without a single blip in the airlock. Or airlocks can start or stop or start and stop again, for a ton of other reasons, like temp changes, getting nudged by the cat or the vacuum cleaner, changes in barometric pressure, but your beer could still be fermenting fine.

Or the co2 is coming out the lid, or the grommet or the stopper. Nothing wrong with that, if co2 is getting out, nothing nasty is getting in.

That's why you need to take a gravity reading to know how your fermentation is going, NOT go by airlocks, or size of krausen, or a calendar, the horoscope or the phases of the moon (those things in my mind are equally accurate).

The most important tool you can use is a hydrometer. It's the only way you will truly know when your beer is ready...airlock bubbles and other things are faulty.

The only way to truly know what is going on in your fermenter is with your hydrometer. Like I said here in my blog, which I encourage you to read, Think evaluation before action you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in.

I've never EVER needed to re-pitch, and I've been brewing more than lkely far longer than you have....Take a gravity reading.

And as to aerating again shouldmyou need to re-pitch whitch you won't, DON'T!!!!!!!!!!!!!!!

You have more beer than not in there, if you add oxygen, you will have liquid cardboard.

Oxygen and fermented beer is BAD.

Only for big beers should you ever consider adding more ox ygen and that is ONLY within the first 12 hours or so since yeast pitch, BEFORE fermentation begins....

 

[chefbri]

I use a refractometer. It's been at 7 brix or 1.028 for 7 days. After the first 3 days I stirred the settled yeast back into suspension thinking that it was stuck. 4 days later I get the same reading.

 

[Revvy]

You do know that using a refractometer on already fermented beer, isn't quite accurate don't you?

Alcohol corrupts the measurement as it refracts light differently than water does. There are some table out there that supposedly takes it into account, but personally I don't trust them, and since we know a hydromter does work with fermenterd beer I just use that.

And stirring fermented beer is not a good thing...that's a good way to oxygenate your beer.

And having the same gravity reading, even if it's high, doesn't mean that the yeast is dead...Just that it is finished or stuck...that doesn't mean yeast is dead...

 

[Revvy]

If your temp peaked to 85 then more than likey the beer is done..The yeast wouldn't have died, they would have gone crazy and burned through the fermentables.

 

[COLObrewer]

OK then, what's the recipe? By the way my rafractometer convertor says that should be 1.016, I don't trust brix for finished beer though.

 

[chefbri]

I did not know that about the refractometer. This is my first time using it, I thought I was upgrading. I will dig out the hydrometer and take a reading when I get home. Thanks for everyones input!

 

[Revvy]

I did not know that about the refractometer. This is my first time using it, I thought I was upgrading. I will dig out the hydrometer and take a reading when I get home. Thanks for everyones input!

A refractometer is great, especially for All grain brewing, because you can tale a lot of preboil and post boil readings and make adjustments as you go along, plus you only use a few drops of wort, AND you don't have to wait forever for the sample to cool. BUT it has it's limits. Like I said, I don't necessarily trust conversion tables to factor in carbonation and alcohol content. So after fermentation is occuring I go back to old faithful, my hydrometer.