Harvested yeast, jar not full

[Mothman]

On my last brew day, as a bit of an after thought, I harvested and washed some of the yeast.

I'd never done it before, and just thought it'd be fun to try.

I ended up only harvesting a small portion of the yeast cake, and then separated out the yeast from the trub as much as possible through a couple rounds decanting between two sterile large jars.

In the end I was left with not enough slurry to fill the jar I stored in, but didn't think anything of it... I just sealed it up and it's been in the fridge since then.

I'm gearing up for another brew day and thought I should use the stored yeast to see how she goes... but then suddenly had a light bulb come on, that I'm pretty sure I've typically seen/read about filling the jars quite full to minimize the head space in them... and my jar is no where near full.

My stored jar has the band of quite clean yeast at the bottom (I assume it's quite clean as it is a consistent light creamy color), about 2/3 of the jar of liquid, and then 1/3 of the volume empty head space.

In hind sight I should have better planned out my process and selection of jar to store it in... but going forward, should I be worried about this yeast?

I don't know what the downside of the headspace is... infection?

The yeast has been refrigerated for approximately 1 month.

If it's not a concern, I'll go ahead and use it, but if it's a potential problem, I'll play it safe and buy new yeast.

 

[Andrew Hodgson]

I have re-pitched similarly stored yeast (about 1/3 of the mason jar being headspace) and it worked fine, I think the conventional wisdom is that the beer the yeast is sitting in protects it from any surface infections but YMMV.

 

[Mothman]

In my case, I partially washed the yeast by adding boiled/cooled water... so the "beer" sitting on the yeast cake is pretty watered down, which may impact what protection it's offering.