Weird Yeast Question

**CiderRat** · 10-10-2008, 10:45 PM

EdWort mentioned in another thread to swirl the mix to put the yeast back into suspension for splitting up a batch of cider. This made me think of something. Being newbies we always have questions.

Picture this if you may…. You get into a pool that is cold and as still as you can be. The water near your body warms from your body heat. But as you move, you get back into the cold water. Now to the cider question: Do yeast move around in the cider consuming the sugar or just eat what is near them and sink? I did a slight swirl of the carboy, not enough to mix up the lees just a slight tilt and the off gassing increased, does that mean the yeast got closer to more sugar?

If this question ever came up before I apologize for re-asking. Thanks for taking the time to answer this.
CR

lapaglia · 10-11-2008, 12:50 AM

As far as I know yeast have no means of propulsion other than floating on the currents so if you move the must around they will move with the current. Cant say it will take them to more sugar but it will move them to a new area.

gratus fermentatio · 10-11-2008, 02:48 PM

As Lapaglia said, yeast have no means of propulsion other than riding currents. This said, they sort of create their own currents during the fermentation process. By converting sugars into alcohol & carbon dioxide gas, they become lighter & float toward the surface, thereby creating a small current/wake. The individual yeast cells will also clump together into irregular shapes as they do this, which makes the current/wake stronger & more pronounced, and causes the direction of travel to change slightly. There are also bubbles of gas being excreted & they rise to the surface & create currents/wakes. Ever seen a vigorous fermentation through a glass carbouy? You can see one here: YouTube - Liberty Ale fermenting So technically, while yeast have no means of propulsion, they do a great job of getting around! I hope you find this info useful. Regards, GF.

**CiderRat** · 10-14-2008, 10:35 AM

Thanks for the answers and movie. The cider that I have made does not get the movement that the liberty ale did.

I guess I have to hope those little guys and girls get to eat all that nasty surgar.

Thanks again.
CR

lapaglia · 10-14-2008, 07:43 PM

They will. They have managed to do it for a few thousand years. No reason to think they will fail now.