Starsan - why and how doesnt it kill the beer?

[mboardman]

Let me start by saying, Im not a disbeliever in Starsan. I use it, every time I brew. I understand how it works, being an acid.

But... I have to admit a nagging question at the back of my mind....

If its effective as a sanitizer by killing bacteria and other such living microorganisms, why doesnt it also kill the yeast? Or why doesnt it effectively stop fermentation? Ive seen videos on youtube by brewers like me, showing how to do this or that in the brewing process and sometime in the course of the video they always spray down a piece of equipment with a starsan solution. I do it too.

But why doesnt it kill our beer?

 

[mongoose33]

If you take whatever residual star-san solution that might exist and dilute it with 5-6 gallons of wort or beer, the pH in the resulting solution changes almost not at all.

 

[Etnewbrew]

I'm new here but basically what mongoose said. When using starsan as a sanitizer you are adding it to relatively PH neutral water. Changing the water to a PH that kills gems. Once you dump that solution there are very few drops of residual sanitizer remaining. The PH of the added wort far far outweighs the few drops of remaining sanitizer. No affect to kill or harm yeasties.

 

[bernardsmith]

I imagine because there is only a very limited amount of starsan on the SURFACE of equipment and fermenters and you are adding massively large (in comparison) volumes of liquid that totally swamps the thin film of the sanitizer. You don't add starsan to the wort (or to the must, if wine) to sanitize the fermentable liquor like you do with K-meta but if you did add enough of the K-meta to be effective you need to wait 24 hours to allow the SO2 to evaporate off before you pitch the yeast. With brewing you use boiling to kill the bacteria and yeast in the grain. Wine makers tend to avoid heat. The brewing we do is when we make coffee or tea.

 

[WarEagleBrewer]

Same reason I could piss in a barrel of Miller Lite and you'd never know the difference in your 12oz bottle...............wait, maybe that's NOT the same reason.....

 

[mirthfuldragon]

It probably does. Every spray kills hundreds of thousands of yeast - probably millions - if you listen carefully, you can hear their cries of anguish. But there are a billions of yeast so it doesn't matter.

And like others have said, once it is in the beer, the ph will equalize and the concentration drops to the point where it is no longer toxic to the yeast.

It's the same reason we can get pool water in your eyes and they burn for just a bit, but putting bleach in your eyes would be much worse.

Not to jump topics too far, but toxicity is a function of concentration. I saw someone posting some stupid meme on facebook about flouride being used in bug spray and how the government wants to kill us. I did the math and the bug spray concentration is 3 billion times what is in the drinking water. And even at that concentration it would take eating half the bag to hit my LD50 (lethal dose 50% of the time).

 

[mboardman]

OK, thats reasonable. I guess I just visualized the starsan working like the "genesis effect" from star trek 2 wrath of khan...slowly covering the planet from a small point.

 

[mongoose33]

Don't fear the foam!

 

[Revvy]

If you haven't, listen to the original Basic Brewing Podcast episode with Charles Talley the creator of Starsan, he explains how it works, and also talks about how since it's made of phosphates (the same ones in the soda pop we drink and other things) that the yeast love it, and it becomes a yeast energizer for them... And also that it's great for the critters in septic systems too....
That's one of the reasons we always say not to fear the foam...also that the foam is there to get into every nook and cranny....

Then they break it down and eat it...


"Sanitizing with bleach and Starsan Basic Brewing."

 

[ericbw]

Why isn't star San diluted more than usual and used as yeast nutrient?

 

[passedpawn]

The solution to pollution is dilution. I never get a chance to say that. Not sure if appropriate here. If not, apologies.

 

[day_trippr]

[pssst. Don't anyone say anything, but I'm pretty sure the moderator has been drinking! ]

 

[passedpawn]

[pssst. Don't anyone say anything, but I'm pretty sure the moderator has been drinking! ]

Haha, not yet. Just got home.

 

[mboardman]

Nice! Thanks Revvy!

 

[Duffman870727]

Yeast are very tolerant to low pH, you can acid wash them in pH ~2.2 +/- 0.2, in order to kill off possible contaminant organisms in the yeast slurry. Some cells will die in this process (about 10%) but, that indicates those cells were weak and/or in poor health. It will still hurt the healthy cells, to a degree, so this is not something recommended as a standard practice but rather, to save your brew day in an emergency (can't get a fresh pitch in time), or periodic maintenance of your culture to kill bacteria.

Long story short, a brief exposure to a spritz of Starsan ain't somethin' yeast get ruffled about, much less a dilute amount in your beer.

It is worth noting that Lactobacillus is only slightly impeded by low pH, not killed. Starsan does not work on Lacto, or Pediococcus which can tolerate even lower pH than yeast. I use Iostar now, and am much happier with the sanitation results (was getting occasional low level infections using Starsan.)