Yeast effects on cold primary fermentation (36-50 deg)

[elgatovolador]

Hey guys. New-ish to the hobby and about to keg a 5 gal batch for the first time. The beer I’m going to keg is an imperial ipa extract kit using two Omega West Coast Ale II Yeast Slurry packs from NB. I did not use a yeast starter, I just pitched it right in the wort after it cooled down to 78 deg. Yeast temp range is 60-72 deg F.

After brewday I had to leave for work (road warrior over here) and the temperature where I live fluctuated between 36 deg F to 50. It was in my garage and my wife checked the fermagraf every other day and the beer stayed in the 46-50 range. After endless browsing in different threads I found a lot of explanations of cold temperature effects on primary fermentation, such as the yeast going dormant. I also got to read that you can get off flavors from fermentation not finishing all the way through due to unfermented sugars.

I finally came back home 6 days after, and I found the primary fermentor at 56 deg. It had a hefty head of krausen and low airlock activity. From my research, I decided to try and wake up the yeast to make up for messing up and letting it go below the target temp. I took it inside put it in a closet and waited until it warmed up to 60 deg, then carefully mixed the yeast cake with a clean and sanitized metal clothes hanger with no splashing to prevent inducing O2. At this point from me moving it and all, the krausen Head had fallen.

One day after my attemp of trying to nudge my yeast awake, I have airlock activity again and a pretty hefty head of krausen (pictured). I also see yeast particles float from the bottom to the top every once in a while. Beer now sits at 64 deg. Debating on skipping secondary, but will definitely dry hop in about 4 weeks, then cold crash it in my fridge before kegging.

Now that you know my beers life story (sorry for the long post, first timer here), does anyone have experience with almost freezing your primary fermentation like I did? Did it have an effect on the flavor of the beer? I really haven’t found any articles on the effect of cold temperature swings like mine. From what I can tell, fermentation is back up going. I forgot to measure gravity when I did all this but the OG from the recipe is 1.086. When I keg I’ll make sure to measure and update the thread.

Thanks for reading, any input is much appreciated!

(Photos of primary fermentation 6 hours after yeast awakening attempt)

 

[Iseneye]

Need gravity reading.

 

[RM-MN]

The yeast you used makes a difference and I have no experience with that yeast so take my post with a grain or two of salt. Many yeasts will ferment well below their preferred range and for many (but not all) of them ferment very clean at lower temps, nearly like lager. Some of them will go dormant but wake up when the beer is warmed, some simply drop out and quit. Yours apparently went dormant and woke up when warmed. I doubt that it hurt the beer.

When the krausen falls again, warm the beer some more. That may get a little more yeast activity (no more krausen though) and bring the FG lower, which is what you want for an IPA. When the beer clears you can dry hop.

 

[Dland]

If the conditions in your garage are regularly like this, I'd suggest a Fermwrap heater with something like an Inkbird controller, with a little bubble wrap insulation to keep your brew at desired level.

https://www.morebeer.com/products/fermwrap-heater.html
https://www.morebeer.com/products/inkbird-digital-temperature-controller.html

If the yeast got going again, the above batch should be fine, however.

 

[Shackleford_rusty]

I regularly ferment Notty and S05 at and around 56-60f, no off flavors or fermentation issues reaching fg(big beers, stouts, pale ale, don't matter) . That being said, overpitch if at all possible for fermenting cooler on the yeast range. And i always ramp up temperature toward the end of fermentation(room temp 68ish°) to ensure the yeast can finish their job

 

[elgatovolador]

Took a gravity reading tonight (1 week after yeast reawakening attempt) and it’s at 1.010!

I tried some of it (more like the entire test tube) and it had a very strong alcohol flavor and a mild tart finish like the Omega description explained the yeast performed in low temperatures. Overall it tasted like an IPA.

I’m assuming that the alcohol taste is going to be masked by the dry hopping the recipe calls for in secondary. I’m planning on skipping moving to secondary and just dry hopping in the primary in a few weeks before kegging.

All in all, the yeast strain I used somehow managed to keep doing its thing way below desired temperatures...so I’m a believer in reawakening yeast.

If I make this batch again, I’ll try to keep it in the higher end temperature of the yeasts desired temp and experiment how much of a taste difference it makes.

 

[kh54s10]

Dry hop now. There is no reason to wait any longer. In fact if you wait you will be losing some of the hop character that is already there. I would recommend no more than 3 weeks total before packaging an IPA.

And yes, dry hop in primary. Less chance of oxidizing the beer.

 

[Soulshine2]

that pic tells me its a 1.011....read at the meniscus . looks like is done but needs to clear up a lot more.