Questions on peracetic acid

[pete]

Have some questions for those familiar with peracetic acid. We got a 5 gal container of it and the rep said the dosage was 1.6 - 1.9 oz per 5 gallons. Does that sound right?

I wanted to try it in the sani buckets but is this also a good sanitizer to use in spray bottles for connections and the sani cycle in a keg washer?

[S.Brewer]

Hey Pete!
I've had a little experience working with PA, and if you have a titration kit of some sort you could dose to the strength you require. Depending on the % of acting agent the suggested dosing could be fine, but I've used less with a fairly concentrated form and had no problems.
I've only used peracetic to sanitize tanks, and I'm not sure what your kegwasher set-up is like so I'm hesitant to give any advice on that. Hopefully you have some sort of metering system as I've run POS kegwashers that drained out the acid almost immediately (via a leak in the line). I'm not sure what you're paying for PA, but I bet you don't want to use more than necessary.
Just make sure your eyes are covered well, as I had an incident where a hose came loose and splashed some over my safety glasses! Luckily I only needed a half hour under an eyewash station and I was alright.
Good luck!

S.Brewer

[Sulfur]

Well it depends on the initial product concentration...your rep is recommending a 0.3% PAA solution. Go for it. I sometimes go up to 0.5% for peace of mind. Depends on your application. Keep in mind it will foam on you if too strong. As to sani buckets. I personally opt for Iodine or glutaraldehyde or Oxine. For spray bottles just use rubbing or normal alcohol from the supermarket (at least 70%).

[gabewilson50]

Well it depends on the initial product concentration...your rep is recommending a 0.3% PAA solution. Go for it. I sometimes go up to 0.5% for peace of mind.

Close, but that calculation assumes an impossible 100% PAA solution. Normal solutions that we can get our hands on as brewers range from 5-15% Peracetic, the rest normally being acetic acid, h2o2, and water. Depending on which you have you can be using up to 3 times the amount of PAA to get the same final concentration in your rinse.

[Sulfur]

Close, but that calculation assumes an impossible 100% PAA solution. Normal solutions that we can get our hands on as brewers range from 5-15% Peracetic, the rest normally being acetic acid, h2o2, and water. Depending on which you have you can be using up to 3 times the amount of PAA to get the same final concentration in your rinse.

Well it's not that complicated. If the rep recommends a 0.3% solution of his solution then follow the advice. Technically you're right in that it is not 0.3% PAA but 0.3% of the initial solution. It all depends on the start solution and hence the reps recommendations. Me, being extra cautious when sanitizing a fermenter, will sometimes go a little higher in dosage as mentioned above....

[dick murton]

I have always used 150 to 250 ppm - of peractic acid, So if you have to calculate out from the original concentration to get say 200 ppm of the active ingredient, not of the original solution. And some PAA solutions don't require usage at that high rate due to the additives. So just use at the recommended rate, and assume pretty much single use unless at zero C, in which case the contact time is hours, not minutes, let alone seconds. This stuff is VERY temperature dependant, so make sure you check the recommended minimum contact time of fresh solution with the supplier. And it is strongly advised in Europe to rinse off afterwards - so the rinse water needs to be sterile.

Now, where did I put that ClO2 dosing kit, or perhaps I should UV treat the rinse water instead

[pete]

I guess if paa is used for sanitizing tanks it should be OK for use in the keg washer sani cycle. I'll wash up a small run of kegs to see how it works and if there are any problems.

For those that use this in a soaking application, how often do you change out the solution?

Thanks for the input.

[gabewilson50]

I wouldn't recommend PAA for soaking applications.

[pete]

Why not use it for soaking?

[dick murton]

It is quite a short lived steriant, decomposing to non active residues within a couple of hours at room temperature (say 20 C). It is also very agressive towards hose rubber and many rubber jointing seals, so will destroy them rapidly if left in contact with active PAA for very long. Finally it is virtually impossible to tell if it is up to strength without complex titration, so it is not obvious if it is still OK.

It's a shame that one of the easiest to visually assess, Iodophors, are due to become illegal for use in the UK, and presumably Europe in a few months time. Hypochlorite compounds, formulated for soak bath use look like coming back in fashion as a cheap and effective material. I am not sure off the top of my head what other compound types we will be using instead of iodophors, but I know there are other non chlorine comounds around

[matt]

Iodophors!? - Yes no more after October, but how to do our starch test then? That is another subject.

When sanitising fermenters or BBTs, we use the PAA in the soaking tank instead of dumping it down the drain.

As for as checking the strength, beside titration, there is suppose to be test strips out there that measure PAA in PPM. Our chemical supplier is trying to get them for us.

[Ted Briggs]

Mayby this should be another thread but why no IO4 in europe??

[dick murton]

I don't know the reason for banning iodophors - I will have to ask the chemical suppliers

Re starch test - iodine in potassium iodide solution. Never heard of using iodophor - but it sounds a simple solution. Best get some put to one side then

Cheers

[pete]

It is quite a short lived steriant, decomposing to non active residues within a couple of hours at room temperature (say 20 C). It is also very agressive towards hose rubber and many rubber jointing seals, so will destroy them rapidly if left in contact with active PAA for very long. Finally it is virtually impossible to tell if it is up to strength without complex titration, so it is not obvious if it is still OK.

It's a shame that one of the easiest to visually assess, Iodophors, are due to become illegal for use in the UK, and presumably Europe in a few months time. Hypochlorite compounds, formulated for soak bath use look like coming back in fashion as a cheap and effective material. I am not sure off the top of my head what other compound types we will be using instead of iodophors, but I know there are other non chlorine comounds around

Thanks. The lifespan info was what I was looking for and it appears paa is best used in an immediate application.

[matt]

Test strips for PAA - search Lamotte, suppose to read out in PPM.
(I think this was posted before)


Iodine/Iodophor...
Quote from May 2009 issue of Brewer & Distiller;
"After 25 October 2009 it will be illegal to sell iodine and all iodine based products." (iodophor) "Iodine has been removed from our market because of potential toxicity issues."

This come out of EU directives "BPD" and "REACH"

Not sure if or what other products commonly used in breweries will be effected.

...sorry another thread?

[dick murton]

I used to use a sterilant with bromine in. I haven't seen this in action for years, and think this was dropped for similar reasons. Lots of jokes at the time about it being the real reason for "brewer's droop" and that the faire sex actually forced this through

[liammckenna]

get test kits from your supplier.

Ditto on the 0.3%.

Nasty, nasty, nasty stuff to work with.

Wouldn't use it in a keg washer sani cycle. Too short lived in the reservoir.

Once had a neat little gizmo that dosed PAA/H2O2 into the bottle rinser at 0.3%. I believe it was called a Dosatron. Think of it as a controlled venturi tube.

Pax.

Liam

[benself]

The threshold for 99.9% cell death using PAA is 100 ppm. That works out to 5 mL of 15% PAA for every 1 gallon of water. But since I'm paranoid, I usually mix it a little stronger; especially for my spray bottles where I need it to work very quickly. Hope this helps!

[Firkin L]

I've read in a couple of places that PAA kills yeast. Presumeably this is at high concentration levels and not at the "normal" dilution rates used around a brewery?

[dick murton]

Normal strength will kill low levels of reidual yeast and bacteria, but if the plant is not physically clean then the remaining levesl are likely to be so high that the PAA is overwhelmed and so not all yeast or bacteria will be killed off. But this comment applies to any sterilant. If the plant is not clean, the remaining film will help protect the yeat bacteria, and virtually no concentration, certainly not a cost effective concentration, will kill the bugs - so the first priority always has to be to get equipment physically clean before you can sterilise it.

Don't forget - the more appropriate term for chemical sterilisation is generally considered to be "Sanitisation". Only steam or hot water to get all items of plant above 80 / 85 C for typically 20 minutes plus will consistently sterilise

[Firkin L]

Previously, we had been using PAA to sanitise our yeast bucket. Was this a bad idea?

[dick murton]

No - as long as it wash physically clean, the 150 - 250 ppm for 30 minutes at room temperature - say 15 to 15 for UK conditions should be absolutely fine

[Firkin L]

Good, we'll go back to using it then! Thanks:)

[dick murton]

Must read my responses before I submit - this should have read -

"As long as the bucket is physically clean before sterilising, then 150 - 250 ppm PAA for 30 minutes at room temperature - say 15 to 25 C for UK conditions should be absolutely fine"

Also - just make sure it is fully drained out. Ideally the PAA should be rinsed off with sterile water. Now if we had sterile rinse water, we might not always have to have a separate sterilant. Certainly we have to rinse off PAA before the palnt comes into contact with beer / wort etc, but in theory, our water is pretty well sterile

[Gregg]

It is quite a short lived steriant, decomposing to non active residues within a couple of hours at room temperature (say 20 C).
Second this (not that anyone would doubt dick's word anyway). I was unconvinced by the advice from a certain "consultant" that the stuff was good for a day or so, and did some investigation which unearthed research showing that beyond about 4 hours the peracetic was essentially dead. I cannot point to that research now, so you will just have to trust me - or Mr. murton.

[Gregg]

Also - just make sure it is fully drained out. Ideally the PAA should be rinsed off with sterile water. Now if we had sterile rinse water, we might not always have to have a separate sterilant. Certainly we have to rinse off PAA before the palnt comes into contact with beer / wort etc, but in theory, our water is pretty well sterile
Dick, you make this point twice - why the requirement to rinse, please? I thought that peracetic, well drained, was almost ideal as a sanitiser, precisely because it breaks down so quickly, and into products that are essentially neutral or natural in beer anyway?

[Firkin L]

Dick might be referring to the UK requirement to rinse.

[mic_mac]

Dick, you make this point twice - why the requirement to rinse, please? I thought that peracetic, well drained, was almost ideal as a sanitiser, precisely because it breaks down so quickly, and into products that are essentially neutral or natural in beer anyway?

Dick might be referring to the UK requirement to rinse.

As far as I know, all 4 of us are in the UK - & I meant to ask the same question of Dick - certainly in my experience of UK microbrewing, PAA is sold & used as a "terminal sterilant" (i.e. no rinse & I think just breaks down to Oxygen, & a very weak soln of acetic acid?)

E.g. one of the main UK fining & cleaning manufacturers advertises it as
Peracetic Acid 5% (Powerful no rinse liquid terminal disinfectant).

& elsewhere on their site, in an article on cleaning -


Sterilisation of brewing plant and equipment is usually achieved by the use of chlorine in the form of Sodium hypochlorite or Sodium dichloroisocyanurate, or QAC's, Quaternary Ammonium Compounds.These very effective means of sterilisation suffer from one drawback - the need to rinse after use to avoid tainting the wort and beer. This is not ideal since water, whilst potable, is certainly not sterile. It is unlikely that rinse water would contain beer spoilage organisms, however it is becoming common practise to use a Terminal Sterilant such as Peracetic Acid, for the final rinse. Used to spray FV's, CT's, RB's, casks and bottles immediately prior to use, peracetic acid sterilises without the need for rinsing.

I think Dick previously mentioned a possible change to EC law on chemicals allowed to be used in food production.

Most micros simply don't have a ready supply of sterile rinse water (outside of using pretty hot liquor) so PAA seems to be a great solution, if it's allowed!

Interesting stuff Gregg about PAA also not being suitable for soak tank purposes - it is still commonly used for this in many breweries.
What is recommended instead?

cheers,
MikeMcG.

[Gregg]

Interesting stuff Gregg about PAA also not being suitable for soak tank purposes - it is still commonly used for this in many breweries.
What is recommended instead?Well, I would have said iodophor, but now dick suggests that is going to be outlawed here - dick is a real spoil-sport. This is the beauty of bureaucracy - it can cause problems, but has absolutely no obligation to suggest solutions. Will have to start looking again...

[mic_mac]

Well, I would have said iodophor, but now dick suggests that is going to be outlawed here - dick is a real spoil-sport. This is the beauty of bureaucracy - it can cause problems, but has absolutely no obligation to suggest solutions. Will have to start looking again...

Yeah, that bl**dy Dick, but you're nearly as bad - coming in here, with your facts & all :D

I googled a bit more & found this
http://www.cip.ukcentre.com/paa.htm
interesting stuff -

Per Acetic Acid
CH3CO.OOH
Guidance note for the food industry
N.E.M Business Solutions © 2001
General Information
PAA was first introduced as an antibacterial agent in 1955, it has a broad spectrum of activity including bacteria, yeast's, algae and viruses. It finds wide use in the food industry mainly due to the fact that its breakdown products...(oxygen and minor traces of Acetic acid)........ need not be rinsed from the process plant

In general peroxides can be considered as high-energy-state compounds and as such they will be thermodynamically unstable.

PAA is considerably less stable than Hydrogen peroxide, PAA under normal storage conditions will loose 1% to 2% of its active ingredients per month compared to the 1% per year for Hydrogen peroxide.

NOTE dilute PAA solutions are even more unstable, a 1% solution of PAA can lose 50% of its strength due to hydrolysis in just 6 days.

In order to try and stabilise the PAA solution a "stabiliser" either Sodium pyrophosphate or 8-hydroxyquinoline are often added, these remove trace metals that accelerate the decomposition of peroxides. Lower pH solutions of PAA are also more stable, at pH 7 a 1% solution of PAA lost 84% of its strength in one day, where at pH 2.5 only 13.4% will be lost.


Seems to back up your idea that PAA is generally unsuitable for soaktanks.

[Sulfur]

Interesting info. Unsuitable for soak tanks ok. But for a CIP buffer tank should be good for a work week (5 days but dependent on load also), especially if combined with some phosphoric acid for example.

[dick murton]

Sorry, but haven't looked at this for a few days

We have had problems with PAA residues with automated CIP systems, where either they go wrong and haven't scavenged out properly (OK OK, this is a programming / set up fault), or because the drainings from the wall have collected in sufficient volume, particularly in long in / out legs - below the level switch, for the residual PAA to affect the flavour. To be honest, we have never been exactly sure just how it gets in there as there are a multitude of possible reasons.

So by rinsing, we guarantee the CIP supply up to the spary head, the vessel walls and the outlet only contain water as the worst case scenario.

Obviously the problem is guaranteeing the water supply is sterile - and therein lies a major problem - just how do you consistently guarantee sterile water without using chemicals to ensure the water mains downstream of the steriliser , whether a sterile filter of UV, remains sterile at all times ?

However, I know the rinsing of PAA is a requirement of more than just our company, for the same reason - PAA contamination. I can't remember if this is now EU law, but if not technically law, people are getting so scared of "Chemical contamination" which has to be declared on labels.....

Can you imagine a food product label that says "may contain sterilant" ?? I know the wine makers have been doing it for years, and get away with it generally, but try something new and different and watch the sales drop through the floor.

CAMRA are pussy cats on the subject of CO2 blanketing cask beer compared to the response on this topic.

Re PAA degradation - the rate is very temperature dependant, so is much slower in a cold (zero to say +4 C) but with far lower kill effect than at say 15 to 20 C. The slightest contamination with organic material also speeds up the degradation - so poorly rinse kit dropped in a soakbath will wreck the effective strength far more rapidly than clean. The trouble is it still smells pretty much the same due to the acetic acid the PAA degrades to

As for a suitable soak bath sterilant - I don't think anything recently has proven as effective as iodophors - or certainly not when comparing price and "maintenance" required against that of iodophors

Keep looking

Oh yes and don't use hypochlorite - I once tried filling flat bottomed FVs which had been sprayed with hypo sterilant. Wonderful opportunity for a mass cold shower there were so many holes. (I tried it with water first as I supected this might be the case)