Acid Washing Yeast - Methods and Techniques Discussions on Home Brew Forums

Jayrizzle

I had some really old WLP002 in the fridge. It smelled really bad (I think just skunked), but I wanted to make sure it was just yeast.
I mixed up some san star to a pH of about 1.8. Then I chilled this to the same temp as the yeast. At the same time I sterilized some water in canning jars (in a pressure cooker), and chilled this too.
I mixed the yeast (about 1/4 cup) with 10oz of the 1.8pH solution and shook it. I left this in the fridge for just under two hours. At this point I decanted as much as I could, and added the yeast to the sterilized water to get the pH back up.
I then shook this and added a few teaspoons to a 6oz starter (1.030) and discarded the rest of the yeast.
I let this starter get going and stepped it up to about 28oz. After it finished with that wort I cold crashed it and decanted. I washed it with sterilized water. I decanted that, and took two tea spoons of the yeast that settled last (settled on top) as there are many dead cells that likely were on the bottom. I put this in another little starter (about 6oz) and then stepped that up to 2L.
It seems like it's doing well at this point. I plan on cold crashing it, decanting, and pitching tomorrow.

Thym

I can't wait to hear how this comes out.

Jayrizzle

The yeast is working on 4.5gal right now. It's been in there for about 22hr, and it looks like it would have if I had pitched a new starter of WLP002. I may have messed up some other things in this brew, so it's not a great test of this system (unless it comes out good). If all goes well I'll be bottling by this time next week. Stupid soon, I know, but try some WLP002 and you'll see this as more reasonable.

Jayrizzle

So, I bottle after about day 6 and it carbed up in a day (and over carbed in two days, but that was because I added to much sugar). It tasted like crap but that seems to be fading. I'm drinking one right now (12 days after brewing it) and it has improved quite a lot, though still tastes a little like feet. I think some of that is due to esters; as my ferm temp was too high for the first 18 hours, and some of that is because it's still really "green". Oh and also I used some home roasted malt which I didn't age, so something bad could be coming in from that too.

frydogbrews

this is why we isolate variables in research. just an fyi there big fella!

Jayrizzle

frydogbrews said:
this is why we isolate variables in research. just an fyi there big fella!

Yeah... there are many variables and possibilities for disaster in my brewing operation. But all and all, the acid washing things seems to work.
It acted like the original yeast, so I didn't kill it. And theoretically I killed any non-yeast living in it, though it may have been clean from the start.