Sunday, January 8, 2012

Managing Fermentation... Lesson Learned.

So it's been 5 weeks since the Black Fri.P.A. brewday and it's still sitting in the fermentors waiting to be dryhopped. Normally this would mean I was just being lazy and hadn't gotten around to kegging... but this time I have been watching it closely and it's just not done. 5 weeks! Primary fermentation should have taken a week, two at the most... What the heck?! SPOILER ALERT! The main issue here is temperature... Here's how it played out...

11/26 Brewday, split batch into two fermentors pitched 1 packet of US-05 dry yeast into each fermentor. Basement is about 65 degrees, perfect temperature for fermenting a nice clean American IPA (in this case Black IPA) LCD thermometer on side of fermentor is reading 70 through the first few days of active fermentation.

Over the next 3 weeks, as winter creeps in, temp in basement where the fermentors are located slowly drops to around 55. LCD thermometer slowly drops to ambient temp and I assume fermentation is done. I follow my long primary rule and do not touch for three full weeks.

After 3 weeks is up, I take a gravity reading to see where it finished at. I'm expecting it to be low (like 1.010), because I mashed low (147 degrees). But surprise! 1.020! after 3 weeks... What you got there is a stuck fermentation... With extract brewing, this can be expected, I never had an extract beer finish lower than 1.020. But with All Grain, I have never had one finish higher than 1.014... Now, if I was bottling this would be a major issue. If I were to bottle before fermentation was complete, it could start up again spontaneously. The yeast consuming those residual sugars would build up enough pressure in the sealed glass bottles that they would explode. And if you are married, there's no better way to end your homebrewing career than to have a closet full of beer bottles exploding and making a huge mess...

But I keg... so it's not really that big of a deal. If fermentation starts up again, the worst that could happen is the beer will get overcarbonated, and I can fix that by bleeding off pressure and letting it sit. My concern is the taste. An IPA is supposed to be crisp, dry, and bitter... At 1.020 there are enough sugars left that it tastes just a little too sweet. So I would like it to finish lower, ideally under 1.014 IMO...

So I took some action, nothing drastic, I didn't pitch more yeast (yet)... I moved the fermentors upstairs where the temp is a little warmer (65 degrees (I'm cheap, ok? No judge...)) and I gave the buckets a swirl to try and rouse the yeast.


After moving and swirling, I left them alone for another two weeks... I peeked today, there was a thin layer of foam on the surface of each... it looks like both are still in an active (but very slow) fermentation. I took a gravity reading and the left one was at 1.018, and the right 1.014... Come on! 5 weeks! 

But I'm just gonna be patient (lazy) and test them in another week. If gravity readings are unchanged in a week, I will consider more drastic measures... (repitching yeast and putting in a warm bath) Stay Tuned...

So how can this issue be avoided? The easiest way is to choose your style based on the current or upcoming conditions... In the summer when it's consistently 80 degrees, you don't kill yourself trying to keep fermentation temps low on your American Pale Ale, brew a Saison or a Belgian style that uses a strain of yeast that likes the warm temps. Conversely, when your basement is 55 degrees in the winter, you can start thinking about Lagers... ok, maybe 55 is too high for lagers... But! Ever had an Anchor Steam Beer? I have, and I totally love it... Steam Beer is this old style of lager from gold rush California era. This style uses a unique Lager strain of yeast that is OK fermenting at the low end of Ale temperatures. Not many breweries still make this style. Anchor Brewing out of San Francisco is considered the standard of the style. And it's delicious... think American Pale Ale, but with more fruity esters and instead of citrusy hops, they are earthy and woodsy... mmmm...

So can you guess what I'm planning for my next brewday? Also, that kinda leads into the other brewing related thing I did today... I brewed a California Common (Official name of the Steam Beer style) last January and right before the keg kicked, I filled a few bottles with my beer gun. Well the keg kicked on the fourth bottle and I ended up with 3/4 of a bottle with 2 inches of Wyeast 2112 yeast on the bottom. Instead of dumping it, I sealed it up and stuck it in the back of the fridge and forgot about it. 

I took it out and opened it the other day... It was crystal clear and still had plenty of carbonation despite being filled off the keg and having a ton of headspace. I poured off the beer leaving the 2 inches of yeast sludge in the bottle. It was delicious... no sign of infection after a year, so I sealed up the bottle of yeast again and stuck it back in the fridge. Today I decided to make a starter with it. 

Growler I'm using to make the starter on the left, grolsch bottle containing year old yeast slurry on the right.

I probably won't be brewing for 2 weeks, so if it works, I have time to build it up a few times with progressively bigger starters so that I have plenty of yeast for a 10 gallon batch. Reusing this yeast will cut $8 off the cost of brewday... And if it doesn't work, nbd I can buy some fresh yeast and all I've lost is 3/4 cup of dry extract. While this isn't cutting edge, it's a fun experiment for me. Stay tuned for that also...

That's it for tonight, Later...

Edit: Apparent active fermentation on the Wyeast 2112 experimental (to me) starter... 3/4 inch krausen and smells like fresh bread dough... good signs!

1 comment:

  1. I brew an altbier this time of year - 55°F is a nice temp for this style. A kolsch would also be a nice option. Both styles sort of straddle the ale/lager line. Good luck with the IPA!

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