Yeast starter on a stir plate

[BVilleggiante]

Does it mater if your yeast starter on a stir plate is not turned up high enough to create a whirlpool in the starter? There's activity in my starter but no whirlpool. Kind of a dumb question but I don't know.

 

[passedpawn]

no

 

[Phunhog]

The whole idea of a stir plate is to just keep the yeast in suspension and not drop out/settle. As long as the liquid is moving it's good.

 

[passedpawn]

The whole idea of a stir plate is to just keep the yeast in suspension and not drop out/settle. As long as the liquid is moving it's good.

That's not the reason for the agitation. The purpose is to keep the wort moving from the bottom of the container to the top.

The O2 dissolves into the wort at the surface only. When the surface becomes saturated with O2 (which happens quickly), the O2 enters the wort much more slowly. So you want to keep moving the wort from the bottom to the top to get new O2 into it.

 

[Phunhog]

Your right...I forgot to mention the oxygenation point of a stirplate.

 

[daksin]

That's not the reason for the agitation. The purpose is to keep the wort moving from the bottom of the container to the top.

The O2 dissolves into the wort at the surface only. When the surface becomes saturated with O2 (which happens quickly), the O2 enters the wort much more slowly. So you want to keep moving the wort from the bottom to the top to get new O2 into it.

I might disagree here. So much CO2 is being produced you're not getting any O2 dissolving back in regardless of if you're using an airlock, foil, or foam stopper. There is positive pressure out of the flask/other container that no gas is getting back in. The whole purpose of a stir plate is to keep the yeast in suspension.