Author Topic: Quick question about yeast  (Read 2396 times)

Offline Ck27

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 529
  • BeerSmith's Unofficial Spam Police.... Do Not Spam
Quick question about yeast
« on: September 24, 2017, 10:38:21 AM »
So, my latest attempt at a Pilsner last 3 failed I decided to use California Lager yeast untill I get it right so u don't hopefully have to pour another 5 galllons. But I noticed some white clusters on rhe surface of the beer that look like yeast colonies they are basically spread out and look okay just little white clumps. Beer smells fruity and like beer so I'm fairly sure it's okay, tastes normal but being that I thought this was lager yeast is it normal for that to happen because isn't California Lager a bottom fermenting yeast. So why would their be yeast on the top.

Offline GigaFemto

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 356
  • Muonic Matter Rocks!
Re: Quick question about yeast
« Reply #1 on: September 24, 2017, 01:11:14 PM »
California Lager Yeast (Wyeast 2112, White Labs WLP810) is a hybrid yeast that is neither a true lager yeast nor a true ale yeast. I brewed a beer in July that I call Schrodinger's Beer because it is an ale and a lager at the same time, just as Schrodinger's cat is alive and dead at the same time. I used WY2112 and got a nice thick layer of creamy krausen on top during fermentation. That was at 62 F. I haven't used it colder than that.


Offline durrettd

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 392
Re: Quick question about yeast
« Reply #2 on: September 24, 2017, 01:37:48 PM »
The "bottom-fermenting" versus "top-fermenting" distinction is a conspiracy intended to confuse brewers!

Both ale yeast (allegedly "top-fermenting") and lager yeasts (allegedly "bottom-fermenting") work the same way. The yeast cells float around in the wort; when they bump into a sugar molecule they transport it through the cell membrane and metabolize it. They then excrete the waste products: alcohol (AKA "yeast urine") and CO2.  The CO2, in and sticking to, the cells causes lots of cells to float to the surface forming krausen and yeast rafts.

Once the CO2 separates from the cells, the cells sink to the bottom, your fermenter fills with CO2, your airlock bubbles, and your beer becomes carbonated. Chilling the beer allows the liquid to absorb the CO2 better, separating the remaining CO2 from the cells.

Two of the differences between ale and lager yeasts is the lager yeast's tolerance for lower temperatures and their slower activity. Both lager and ale yeasts are active throughout the beer, but at some point someone said, "look at all the krausen on this ale. The lager doesn't have as much krausen. I guess the ale yeast is fermenting on the top and the lager yeast is fermenting on the bottom!"