re-used dry yeast question

[roylee]

I generally use dry yeast (mostly Nottingham) and when the timing is right pitch onto the yeast cake. Of late I've been harvesting, referigerating in pint jars, making a wort starter, etc. My question is this. Dry yeast does not need to be oxygenated. Liquid yeast does. Does my dry yeast, when harvested, become liquid yeast? The FG on what I've made this way has been in the range I expected, but is that luck? Should I aerate the wort before adding harvested dry yeast?

 

[commonsenseman]

Yup, it becomes liquid yeast after it's harvested. You should aerate for all types of yeast though, they all need oxygen to breed.

 

[HomebrewMTB]

Yes, reused yeast is now liquid no matter how it started. That said, I can't see going through the effort and risk of cleaning, sanitizing, and yeast washing just to save $1.50 on a pack of Nottingham. Just because you can, doesn't mean you should. It can be worth the effort to save $7+ on a liquid yeast especially for unique strains. I know this is a DIY hobby so it's not all about economics and everyone's value proposition is different.

And I would aerate no matter which yeast type is used. 45 seconds of vigorous shaking is enough to get to 8ppm (max oxygen levels from air). I tip the carboy on it's edge and shake it back and forth for a minute or two. Plus whatever splashing occurred from transferring.

 

[roylee]

I understand dry yeast isn't that expensive... just wanted to harvest and reuse the lower priced a few times before trying it with the $8 liquid. (Although $1.50 is cheaper than I can buy Nottingham. The nearest store charges $2.75 and it's a 160 miles away) I'll aerate with aquarium pump as I previously have with liquid.

 

[Omahawk]

The nearest store charges $2.75 and it's a 160 miles away)

This is a great reason to reuse dry yeast.