Sediment started bubbling after yeast washing!

[k_alebrewer]

Hi guys,
I've been homebrewing for over 3 years now and each batch has taught me something new.
My latest brew was a Vienna Brown ale with OG of 1.052. This was also my first batch using Fermentis k97 yeast that I sourced from a local brewery. Mash was a two step process with accurate temp control. Aerated it by shaking the fermenter for quite some time. I also used a starter to pitch adequate healthy yeast cells. Fermentation went well with high Krausen at 3-4 days and FG of 1.010 at day 10. Transferred it to secondary to clean out.
As a regular habit I washed the yeast sediment for harvesting this k97 strain. To my surprise, as soon as I transferred the sediment to my Mason jars and left it for settling, I saw bubbling from within the sediment. After a couple of hours there was actually Krausen inside the Mason jars!!
According to me it was the co2 bubbles trapped inside the sediment that got released. But I can't be sure. Has anyone experienced the same? What could be the possible reasons for this bubbling of the sediment?

P.S - The FG was stable for 3 days before I transferred it to the secondary.

 

[chinsi]

seems a little unusual, what is your yeast washing procedure like? I typically leave it overnight but I definitely don't recollect any bubbling. Did you take a picture of the krausen by any chance?

 

[k_alebrewer]

Yeast procedure is pretty standard. Sterile water in slurry, shake it up, pour in mason jars and leave it 4-6 hours in refrigerator. Decant and use yeast strata in next batch. Below is the pic. All I see is trub and beer... No yeast strata.

View attachment 1441971210302.jpg

 

[flars]

At the bottom of your flask you have some hop debris, break material, and lots of yeast. Whether or not you see a line of creamy white yeast depends on the flocculation rate of the yeast. A yeast that flocculates more rapidly than another, will be mixed with the other materials poured out of the fermentor. A yeast that stays in suspension longer will show as a creamy white line at the top of the other material, but even in this situation, there is a lot of yeast below.

Take a look at this thread for a better explanation.
https://www.homebrewtalk.com/showthread.php?t=519995

 

[k_alebrewer]

Thank you flars for the link. But what about the Krausen after I transferred it. It's like the yeast is fermenting all over again. I can't seem to find any information / explanation for that matter.
The picture you see above is actually after 6-7 hours of settling.
Gravity reading shows no change.

 

[brrman]

Sometimes an injection of oxygen can get the yeast to wake up and bubble a little, but it will not do much without any food in there. I would not be worried about anything.

 

[k_alebrewer]

Thanks for the reply guys. I harvested it anyway and now some of it is already fermenting a new batch. Cheers.

 

[chinsi]

a little late, but I'm going to second flars on this. I wouldn't call it krausen because technically the yeast have no available sugars to them, the layer of bubbles is just from waking up the yeast cells while transferring.

Not sure if you make starters but harvesting yeast from the starters is a much cleaner method instead of harvesting it from the trub at the end of fermentation. I switched to this method from the trub method and it really makes life easy.

http://brulosophy.com/methods/yeast-harvesting/

 

[k_alebrewer]

Hi chinsi, excellent link. And yes, I do harvest yeast from starters too. Infact this k97 strain that I got was in extremely small quantity ( 10% sediment of a 25ml vial). So I made a starter with initially 700ml. I then harvested yeast from this sediment, put some for cryo preservation (15% glycerol at - 80°C at my friends lab) while the rest was used in the above mentioned batch. For continuing the use of this strain, I harvested it from the fermenter sediment.