Wash your yeast with Star San?

[debaniel]

I've been reading "BEER: Tapping into the Art and Science of Brewing" by Charles Bamforth (great read, by the way - lots of technical scientific stuff for us brew-nerds)

He has this to say about washing and storing yeast (on page 151):

"The yeast may also have picked up some contaminants in the fermenter, which must be gotten rid of. This can be achieved by washing the yeast for an hour or two in a solution of phosphoric acid at PH 2.2. Yeast survives this treatment quite happily, but bacteria don't."


Now, I know that Star San is roughly 50% phosphoric acid... but I also know it has a few other ingredients in there... my question is, if you really wanted to wash the bacteria out of the yeast, could you dilute the Star San to a PH of 2.2 and actually wash your yeast with that before putting the little guys to sleep in a mason jar?

Speaking of which, what is the PH of properly diluted Star San? I know that once it hits 1.7 or below, it stops being an effective sanitizer... I'm assuming it's over 3?

 

[conpewter]

Actually star-san is effective until it's PH goes above 3 or so. After that it should be refreshed with more star-san or phosphoric acid.

I tried to wash my yeast once in star-san and it was a failure, that doesn't mean it won't work for you though, give it a try and see!

 

[GilaMinumBeer]

IIRC, it needs to be at pH 3.5 or lower.

It's when it becomes more alkaline than pH 3.5 is when it become less and less effective.

Charley Talley (5 Star Chem) would be an excellent candidate for this question and I would be greatful to read the response. I am not sure if it would be appropriate to link his email addy here so, if you want it PM me and I'll provide it to you (free of charge even).

 

[Piotr]

"The yeast may also have picked up some contaminants in the fermenter, which must be gotten rid of. This can be achieved by washing the yeast for an hour or two in a solution of phosphoric acid at PH 2.2. Yeast survives this treatment quite happily, but bacteria don't."

This is normal routine, used in almost all commercial breweries. But once I've read an article:
http://www.birkocorp.com/brewing/yeast.asp
that acid actually hurts the yeast a bit, and better method is washing yeast with 5 ppm solution of chlorine dioxide (ClO2), and I do it with my slurries ever since. Seems to work fine, I'm a bit suprised that breweries still use acid. Maybe the ClO2 is in practice not as effective as they prove in that little experiments.

I don't know what StarSan contains, but I think it is basically ClO2.

 

[Funkenjaeger]

I don't know what StarSan contains, but I think it is basically ClO2.

It's phosphoric acid and some kind of surfactant, so I don't think it's the same at all.

 

[ThatFishGuy]

completely a side story, but i couldnt help it.... Charles Bamforth is one of my teachers! and yes is book is really good. glad i bought a new one and not used! maybe i can just ask him this question?