Yeast Starter

Does STAR SAN HB kill yeast cells and should it not be used while making starters ?

No! Star-San is your friend. From your beaker (or anything else for that matter) drip out the liquid but the foam remains. As they say.... "don't fear the foam!"..

Ya, dumb question. I've been making yeast starters for years and not had a problem. Now all of a sudden the yeast died in my last two starters, fermentation is not completing leaving me with a diacetyl problem. Coincidence or maybe I just need a vacation.

JohnnyMac said:

Does STAR SAN HB kill yeast cells and should it not be used while making starters ?

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When STAR SAN is diluted, it actually acts as a yeast nutrient, I believe. So the foam that is left behind isn't a terrible thing as it's diluted with your starter or batch.

JohnnyMac said:

I've been making yeast starters for years and not had a problem. Now all of a sudden the yeast died in my last two starters, fermentation is not completing leaving me with a diacetyl problem. Coincidence or maybe I just need a vacation.

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When you pitched the yeast, did you see signs of fermentation? Do you cold crash and decant, or do you pitch the entire starter? What were the OGs?

I really doubt that StarSan will act as a yeast nutrient given it's composition. Certainly given the effect it will have on the pH for suitable yeast strains it will benefit things when it's diluted in small amounts, but there's really nothing in there the yeast can use for nourishment.

I recall reading on the Five Star website that starsan will kill bacteria, yeast and most moulds at the correct dilution, but once added to a more neutral volume of liquid, this effect will most certainly be muted.

antiphile said:

I really doubt that StarSan will act as a yeast nutrient given it's composition. Certainly given the effect it will have on the pH for suitable yeast strains it will benefit things when it's diluted in small amounts, but there's really nothing in there the yeast can use for nourishment.

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I read somewhere that the phosphorus acid can act as a source of phosphorus for the yeast. Perhaps I was misinformed?

bobo1898 said:

I read somewhere that the phosphorus acid can act as a source of phosphorus for the yeast. Perhaps I was misinformed?

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As with a lot of brewing lore, "yes, somewhat."

Phosphoric acid on its own can do some sanitizing, but if that were all it took, a can of Coke could be employed for the same purpose. Phosphoric acid can make a lot of pH adjustments in the brewing process, including the fermenter. Yeast don't need much phosphorus as an additional nutrient. Yeast need nitrogen and often phosphorus is just along for the ride. StarSan doesn't have any nitrogen.

Properly made, StarSan is corrosive to organisms as a sanitizer. The Phosphoric acid lowers environmental pH and the second ingredient (dodecylbenzenesulfonic acid) acts as a surfactant and oxidizer to compromise cell walls. The surfactant also helps form and maintain the foam that shows Star San has been used effectively.

When wort is added to a container where StarSan has been made and used properly, the dilution should buffer the pH and render the surfactant harmless. Yeast are very tolerant of a wide range of environments and can change a lot of sanitizing compounds into other molecules. Changing chlorine to chlorophenol is just one example. Happily, neither ingredient in StarSan seems to get converted into an objectionable flavor.

Everything is toxic to an extent.  The key consideration is concentration of the material in question.  You will die in a full Oxygen environment, but need Oxygen to survive.  Likewise, you need water to live, but every year people drown in water.

I went back to an early Brew Strong episode where John and Jamil interviewed Jon Herskovits of Five Star Chemicals about sanitation.  Jon mentions that the 'breakdown products' of Star-San may be utilized by yeasts.  He notes that this is in response to heavily diluted amounts of Star-San (as in residual foam).  [citation: Brew Strong episode 'Sanitation with 5-star' airing 1/5/09].  In reality, they would be in such a dilute concentration that I don't know how one could definitively state one way or the other.

In usable form, diluted according to instructions, Star-San is an accomplished sanitizing agent, which is to say that it destroys or cripples bacteria, yeasts, and other organisms to prevent and impede them from multiplying.

I use Star-San to sanitize my equipment just before use.  Depending upon how I left it, I have sometimes treated my flasks with Star-San and left the foam in the bottom as I pour in starter wort.  While I have not studied it in depth and do not have a clean study to resort to, my cell counts on those starters which have been made on some residual Star-San are well within what I would expect for cell counts and not differentiated from those starters where the Star-San had long since dried before use.  Given the wide amount of error in my cell counts, this does not amount to much except for anecdotal evidence (very weak).