Star San acidity and yeast collection...

Anyone know the PH of properly mixed Star San? I made a batch of hefeweizen a few days ago which fermented pretty hard. I took off the airlock and put a blow off tube on which went into a half gallon jar half filled with Star San solution. This evening I took the blow off tube off, put a regular airlock on, and looked at the jar. The jar has a nice white layer of yeast at the bottom. Does anyone think this is viable yeast? Essentially it seems like it got an acid wash and is now sitting at the bottom of a contamination free environment. I've harvested and refrigerated a lot of yeast and this stuff looks pretty healthy. What do you people think?

Ah... Star San is designed to kill bacteria AND yeast (like the wild ones that would otherwise contaminate our beer). Your yeast are likely dead or severely wounded unless you had so much blow-off it diluted the Star San enough to raise the pH above its kill zone.

GT

I've heard that Star San only kills bacteria and not yeast. It kills the bacteria by rupturing cell walls just like an acid wash would do. I might make a one pint starter tomorrow to see what happens if I pich the yeast in it.

It kills yeast too. http://www.fivestarchemicals.com/tech/starsan.pdf

Star San has to be below pH 3.0 to be effective.

I'm going to try it today. I think it will work. Star San needs to be below 3.5 pH according to Palmer and yeast is washed with a solution of 2.5 pH liquid. In How to Brew Palmer talks about it being a bactericide and doesn't mention anything about yeasts. If it doesn't work, oh well; if it does, we've all learned a new way to collect yeast in a sanitary way.

RayInUT said:

I'm going to try it today. I think it will work. Star San needs to be below 3.5 pH according to Palmer and yeast is washed with a solution of 2.5 pH liquid. In How to Brew Palmer talks about it being a bactericide and doesn't mention anything about yeasts. If it doesn't work, oh well; if it does, we've all learned a new way to collect yeast in a sanitary way.

Click to expand...

Wild yeast are just as problematic as bacteria and Star San kills them to. It has no way of distinguishing between bad yeast and good

Per Star San: http://www.fivestarchemicals.com/tech/starsan.pdf

v BENEFITS
v Broad Spectrum Bactericide and Fungicide

Click to expand...

P.S yeast are fungus

As I said if the blow off diluted it enough you may have viable yeast still but it would not be my choice of methods for yeast propagation...

GT

It doesn't look like the yeast is viable. Normally my 3068 starters take off almost immediately and this one has been sitting out for hours with no activity. All in all it was worth a try. We don't learn unless we experiment. This one appears to have failed. End of story unless a miracle fermentation begins.

UPDATE...the starter took off yesterday. The yeast must have been shocked but not dead! I might go get an acidity testing kit today to test the star san. I made some vinegar that I wanted to test anyway.

I imagine that if you got any viable yeast out of it, it's because the Star San had risen to a pH of 3.5 or higher. I have to admit, I have looked at that perfectly white yeast cake on the bottom of my blowoff vessel, but realy didn't think it would do anything.

This makes me wonder though, if the regular yeast can live, what else can? I don't want some other wild yeast making a home in the blowoff vessel and crawling into my beer somehow. I know it probably isn't likely, but I think I may go with alcohol for my airlocks and blowoffs now instead of Star San.

Definitely let us know how that beer turns out with that yeast, I'm interested to see how clean the fermentation is.

When you acid wash a yeast they say to use an acidity of 2-2.5pH. So, if star san is effective with a pH of 3.5 it kind of makes you wonder. BTW, I usually do use vodka for my airlocks if I'm flush with vodka. If I'm down to half a bottle though it's time for star san!

It sounds like the Star-San worked as advertised, reducing the level of yeast dramatically but not to zero. The small amount of yeast left (perhaps thousands of cells) have grown up somewhat in a nutrient rich medium. Everything has worked the way we should expect.

I don't think the acidity of the Star-San is an issue per se, since straight phosphoric acid at a pH of 2.5 (acid washing) would have left most of the yeast viable anyway. The Star-San clearly killed almost all of the yeast here.

So would the yeast that did propogate be a pretty clean strain then? You would think that you could use this with very little worry about infection or contamination. Tomorrow I will add another pint of water with 1/2 cup DME.

I was poking around and found this thread; Does anyone know if the experiment went any further or did anyone else try a similar experiment?