Did I underpitch my yeast?

[jakenbake]

Did an all grain Pumpkin Ale this weekend. It was my first 10 gallon brew, and I didn't hit my mash temps (was at 146F for most of it).

Anyway, I just doubled a 5 gallon recipe. OG was 1.060. I used 2 Wyeast 1056 American Ale packs for the 10 gallons (no starter). Fermentation really took off Sunday morning, but Monday night there wasn't much of anything. I had to wiggle the blow off tube to get any bubbles in the water.

I am fermenting in a well cleaned Sanke keg since it is a 10 gallon batch and I didn't want to split between 2 carboys.

I originally set my fermentation chamber for 68F, but taped the temp probe to the sanke keg, so it may have undershot the temp by quite a bit to get the stainless steel keg down to temp. As of Monday morning, the temp chamber still wasn't to temp, and the fridge was on trying to get there. By Monday night, it was at temp.

Anyway, I'm not sure what the deal is on the stalled fermentation. Right now I have it warming up in hopes that I can get it active again. Should I just let it play out, or should I try to stir the yeast without aerating, or pitch more yeast?

Oh, and I used 2 lbs of brown sugar in the boil. Not sure if that had anything to do with it.

Any advice would get great.

 

[COLObrewer]

You don't know that it is stalled, take a gravity reading and see how close it is to the projected FG, then take another in 3 days and see if the gravity is stable, If you are close to FG and your gravity is stable then fermentation is done.

 

[jakenbake]

Well, thanks for knocking some sense into me. I haven't had time to take an gravity reading until tonight. I'm sitting at 1.004 (to be expected since I mashed at such a low temp). Really wanted to be at 1.017 per the recipe. Definitely didn't underpitch...

Should I rack to a secondary now, after 5 days, or just leave in the primary for another week?

 

[KISS Brew]

Well, thanks for knocking some sense into me. I haven't had time to take an gravity reading until tonight. I'm sitting at 1.004 (to be expected since I mashed at such a low temp). Really wanted to be at 1.017 per the recipe. Definitely didn't underpitch...

Should I rack to a secondary now, after 5 days, or just leave in the primary for another week?

1.004 seems awfully low (like, impossibly low). Did you correct for temperature?

I never rack to secondary, so my advice would be to leave it in the primary for at least another week.

 

[jakenbake]

I couldn't believe it either. I'm attributing it to the fact that I had such a low temp mash and added 2lb of brown sugar to the boil. I did an actual attenuation measurement (not apparent) and it came out to 74%, which is right between 73 and 77 stated by wyeast (I'm using American Ale 1056 in case I didn't mention it above).

I'm thinking the same thing about just keeping it in the primary.

 

[jestmaty]

Yes, you made beer. Started at .060 and finished at .004, you made beer and it's done fermenting, but as everyone else says...let it sit for a total of 2-3 weeks since pitch to let the yeast finish cleaning up the beer if you don't go to a 2nd. Sometimes I rack to 2nd, sometimes not. Depends on how lazy I am.

For a while back in May and June, my batches were finishing in the low single digits too... I think my cooler-converted-mas-tun was not keeping temp during my hour long mash. Might start at 152*, but by the time the hour was up, I was in the mid/upper 140's. Result is a drier, less bodied, high alcohol beer.

On almost all my AG batches, I get a pretty active fermentation 24 hours after pitching my dry yeast and it goes hot n heavy for the next 2 days, then slows to a trickle on the 4th day. By day 4-5 and beyond, the airlock is virtually silent.

Relax..you know the rest.

Dry, thin, high alcohol, extremely clear hefeweizen AG..

 

[dstar26t]

To answer your original question, you did not pitch enough yeast if you go by the .75 Million cells/mL/ºP standard. You would have needed 417 Billion cells and you pitched 190 Billion at best. Some breweries pitch as low as .5 Million cells/mL/ºP but you did .342 Million. Use twice as much yeast next time and see what that does to the flavor.

 

[jestmaty]

dstar26t, I'm still in the learning stages myself... been ag brewing for right at one year, every batch used dry yeast.. Danstar Munich, Fermentis WB06, Safale US 05, etc..

If he got that highly loaded batch of fermentable wort to drop from .060 to .004, didn't the yeast do their job? Or was it too quick?

I understand there's a whole bunch of beer tools available out on the web, and to be honest, I don't have even one downloaded on any of my computers.

Also, I get that there's a recommended number of yeast cells per liter, but I ask again, if he got attenuation, accounting for his low mash temps, why/how was he only halfway to the yeast count?

Not starting an argument, just learning still...

 

[kh54s10]

Definitely under pitched! Yes, under pitched wort will ferment. And yes, you may get good beer from an under pitched batch. But, the chance of off flavors or other problems is greatly increased.

Mrmalty suggests 4.9 packs and that is assuming yeast only a couple of weeks old.

As to getting such a low gravity I would suspect the low mash temperature. For the speed in which it fermented I would say that the time it took to get the fermenter to temperature (too warm) made the yeast work fast.

jestmaty, Read the info on yeast starters on mrmalty.com and yeastcalc.com

 

[dstar26t]

Or better yet, read "Yeast" by Jamil Z. and Chris White.

 

[kh54s10]

Or better yet, read "Yeast" by Jamil Z. and Chris White.

I would have suggested that also but it's not online. I still have it on my list of books I want to get --- eventually.

 

[jestmaty]

Thanks to you both!

I look again at the OP's #'s... 1.060 and 2 1056 yeast packs for 10 gallons. Was it his high(ish) SG that necessitates extra yeast?

I've had a few ales that started at like .058 and just used one pack of Danstar Munich (for wheat ale), and they came out just fine.

On the other hand, I've also had few batches end up kinda skunky and flat... but that was traced down to a bad capper. Wasn't getting an airtight seal with my wing capper and it let oxygen in and didn't cause the CO2 to dive back into the beer like it was supposed to.

FWIW, I only brew AG kits that can be bought from places like Austin Home Brew, or Midwest Supplies, or Northern Brewer.. not making up my own recipes just yet.

But, I also haven't read that some batches require as many as 4 packs of yeast either. (Taking into account the OP's 10 gallon quantity)

I WILL read up on those two topics ya'll provided me above, thanks! Jerry

 

[kh54s10]

Thanks to you both!

I look again at the OP's #'s... 1.060 and 2 1056 yeast packs for 10 gallons. Was it his high(ish) SG that necessitates extra yeast?

I've had a few ales that started at like .058 and just used one pack of Danstar Munich (for wheat ale), and they came out just fine.

On the other hand, I've also had few batches end up kinda skunky and flat... but that was traced down to a bad capper. Wasn't getting an airtight seal with my wing capper and it let oxygen in and didn't cause the CO2 to dive back into the beer like it was supposed to.

FWIW, I only brew AG kits that can be bought from places like Austin Home Brew, or Midwest Supplies, or Northern Brewer.. not making up my own recipes just yet.

But, I also haven't read that some batches require as many as 4 packs of yeast either. (Taking into account the OP's 10 gallon quantity)

I WILL read up on those two topics ya'll provided me above, thanks! Jerry

The difference here is the type of yeast. Pitching one pack of dry yeast is enough for average 5 gallon batches. Dry yeast packs contain a lot more yeast cells than are in a pack/vial of liquid yeast. So the 10 gallon batch should get two 11.5 gram packs of dry yeast.

BTW, I use Northern Brewer's kits as a guide for my own recipes. (have made a few of their extract and partial mash kits) I look online at their recipes and ingredient lists, decide if I want to alter them and check my stock then work up my own recipe with Beersmith.

 

[dstar26t]

For Ales, your baseline should be .75 Million cells per mL per ºP. Convert your batch size to mL and convert your OG to Plato. Dry yeast has 20 Billion cells per gram when new if properly re-hydrated, they lose 4% per month refrigerated. If pitched without re-hydrating in water, assume half the cells die. Wyeast and White Labs packages have ~100 Billion cells when new, assume 95% viability with a week old package.

 

[jestmaty]

For Ales, your baseline should be .75 Million cells per mL per ºP. Convert your batch size to mL and convert your OG to Plato. Dry yeast has 20 Billion cells per gram when new if properly re-hydrated, they lose 4% per month refrigerated. If pitched without re-hydrating in water, assume half the cells die. Wyeast and White Labs packages have ~100 Billion cells when new, assume 95% viability with a week old package.

Again, lots of research to do on my part...

I'm floored to read that maybe 1/2 will die if not rehydrated, wow!

It's so easy to rehydrate yet I've NEVER done it. Much easier than making a starter for liquid yeast?

Again, I've never rehydrated, but will on my next batch to help maintain viability of as much yeast as I can.

Thanks all so very much for continuing my education :rockin: