How long is PAA sanitizer good for after dilution?

[piojo]

I assume it will vary by brand, but how long is peracetic acid sanitizer likely to keep its strength after being diluted for use as a no-rinse sanitizer? I imagine it will go bad as the hydrogen peroxide degrades and the equilibrium balance ensures that there is also less PAA in solution.

Has anyone used PAA and tested its strength after a couple days?

 

[redllama]

I was poking around on the probrewer message boards as well as some industry spec sheets and it seems like the MAX is 1 week if kept at room temp or below. It is suggested that you use test strips daily to make sure the concentration is at an acceptable level

 

[Qhrumphf]

I generally won't trust it more than 48 hours once diluted to use strength, and usually no more than 24 hrs, but that's a better safe than sorry approach, and depends on the concentration.

Easily titratable with a peracetic acid test kit. As long as enough PAA remains (and not decomposed), probably still good.

That said, PAA is wonderful stuff but quite hazardous when concentrated and smells very unpleasant, and probably not the best for home use. Do exercise care using it (chemical gloves, goggles, better yet face shield). It burns the skin painfully and quickly. And you DEFINITELY don't want it in your eyes.

 

[Sadu]

All the commercial brewers I've visited use this stuff. What is the pros and cons vs starsan?
Sounds like it has less shelf life and is more toxic.
Presumably it works faster and kills more bugs? Or is it just cheap AF?

 

[piojo]

All the commercial brewers I've visited use this stuff. What is the pros and cons vs starsan?
Sounds like it has less shelf life and is more toxic.
Presumably it works faster and kills more bugs? Or is it just cheap AF?

Breweries use it because it doesn't foam (unless foaming agents are added), and it's strong as hell. It is only cheap if you buy in quantity (or you know someone), since it's not a consumer product. There are good formulations and bad. Plain PAA takes ages to kill and needs a high concentration, but I imagine most breweries will use the improved formulations, just as someone that uses "acid sanitizer" is not using plain phosphoric acid. So I can only speak for Ecolab Vortexx, as that's the one I looked into.

Starsan lasts longer and I think it's more resistant to being soiled. Starsan will last forever while concentrated, but PAA will degrade, hopefully over a period of years. PAA should kill faster, and it will kill many things that Starsan won't. They use the same dilution and are both no-rinse. If you are using a bad formulation, it may not work because it needs a pretty high concentration.

If you don't think you need it, you probably don't. I may need it because my procedures aren't well-established and I sometimes need to sanitize things quickly. Currently I'm using iodophor, which is just a bit faster and stronger than Starsan.

 

[Vale71]

All the commercial brewers I've visited use this stuff. What is the pros and cons vs starsan?
Sounds like it has less shelf life and is more toxic.
Presumably it works faster and kills more bugs? Or is it just cheap AF?

PAA in the right concentrations will kill everything including viruses and spores. Starsan is just acid washing.

 

[RPh_Guy]

Umm isn't the active ingredient in Star San the DBSA?

The phosphoric acid is to drop pH to where DBSA is active?

 

[Vale71]

DBSA is only a surfactant, its job is just to make sure surfaces stay wet long enough. The acid will kill or just seriously maim bacteria, depending on their PH tolerance.

 

[RPh_Guy]

OK, then why is it listed as an active ingredient?

 

[Vale71]

I guess because surfactants do have an ancillary effect on the product's properties (surface tension) even if they don't kill microbes directly?
Non-active ingredients IMHO would be for example just coloring agents or preservatives.

 

[piojo]

The category is "acid anionic sanitizer", and it wouldn't work without both. Chemically, phosphoric acid is a mineral and DBS acid is organic. They probably don't work the same way at all. The DBS acid is the anionic surfactant. I'm not sure whether phosphoric has an effect of its own, but certainly you can use some different anionic surfactants (but not any).

 

[Vale71]

I'm not sure whether phosphoric has an effect of its own, but certainly you can use some different anionic surfactants (but not any).

Yes it does. Acid washing with phosphoric was used to treat harvested yeast in order to reduce the level of contamination with beer spoiling organisms, the idea being that yeast is more resistant to extremely acidic environments than most unwanted guests. The downside is that yeast vitality is affected to some extent too.
You would not need a surfactant at all if you were to always fill your containers to the brim, but since StarSan is intended to be only sprayed on the surfaces you do need a suitable surfactant or the solution will slide off some hydrophobic materials way too fast for it to have any effect at all.

 

[RPh_Guy]

It's pretty easy for me to find articles on the antimicrobial activity of alkyl benzenes. Certain surfactants are active against microbes.

It's not just in there to keep surfaces wet.

 

[redllama]

All the commercial brewers I've visited use this stuff. What is the pros and cons vs starsan?
Sounds like it has less shelf life and is more toxic.
Presumably it works faster and kills more bugs? Or is it just cheap AF?

I used it when I worked at a commercial brewery and it definitely has it's pros and cons. Compared to star san it was cheap because we pulled it out of a 55 gallon drum and only used a couple ounces at a time. Being non foaming is a necessity when you are pumping everything through CIP to sanitize.

You definitely have to be careful with it in its non diluted form as it will burn you in no time. The smell isn't great either, and got help you if you didn't get all the caustic out of the measuring cup before adding the PAA as the smell will just about knock you out. I loved using it in the brewery but just don't see it as useful on the home side of things.

 

[Qhrumphf]

I used it when I worked at a commercial brewery and it definitely has it's pros and cons. Compared to star san it was cheap because we pulled it out of a 55 gallon drum and only used a couple ounces at a time. Being non foaming is a necessity when you are pumping everything through CIP to sanitize.

You definitely have to be careful with it in its non diluted form as it will burn you in no time. The smell isn't great either, and got help you if you didn't get all the caustic out of the measuring cup before adding the PAA as the smell will just about knock you out. I loved using it in the brewery but just don't see it as useful on the home side of things.

Simple solution is chemical-specific containers so they never mix.

And yeah, mixing concentrated chems is bad news.

Stone's Richmond facility had to briefly close a while ago (I think it was for a day). From what I understand chems got inadvertently mixed and started releasing fumes. Turned out to be nothing serious, but abundance of caution. But still illustrates how serious the issue can be.

And there's the old "caustic into a tank full of CO2" thing (tank implosions yay!) that's really easy to do for someone who has just enough knowledge to be dangerous.

Industrial chemicals, including those used in commercial breweries, are "industrial" for a reason.

And unless you need PAA for CIP, you probably don't need it. Heat and iodine are plenty effective for home use.

(I much prefer iodophor to star-san for the record).

 

[piojo]

And unless you need PAA for CIP, you probably don't need it. Heat and iodine are plenty effective for home use.

Heat or iodine can do CIP as well, and iodine should cost less (based on the wholesale cost of iodophor powder). So is the main reason kill time or kill amount (near sterilization)?