Pink Peracetic Acid

[therichieboy]

Hi fellow homebrewtalkers,

Been a while since I said anything on these forums so nice to be back. Pls don't burn me for my following question. I've done a menial search here and across the www and am stumped.

So........ We've recently acquired a 100l automated stainless system and as a prerequisite of going commercial (here in Israel) we need to use peracetic acid as a sanitiser.

Now I'm very familiar with peracetic acid having worked in commercial breweries in the UK but never have I seen what I'm seeing now: after sanitising though our CIP system the peracetic acid is coming out a pinkish color. Then, when recycling it to our bottle washer we're getting dark pink/purple residue.

I checked with some of my mates from the commercial brewing industry in England and they're stumped.

The locals here have ruled out any deliberate inbuilt mechanism in peracetic acid that may stain it (I don't read Hebrew so well). My only conclusion is that it is due to residue from a red scouring cloth we used on the heating elements that got lodged in our pump.

Any ideas? ?

Cheers

 

[therichieboy]

......bump......

 

[day_trippr]

fwiw, while I recognize it is a legitimate sanitizer, I don't recall anyone on HBT posting about their use of peracetic acid...

Cheers!

 

[bucketnative]

We regularly use PAA in our lab, but I have never seen anything turn pink or purple. (I've seen plated brass turn green with corrosion.) If the scouring cloth is nylon, that might contribute as many acids are solvents for nylon. Why it changes color in your bottle washer may be another mystery altogether.

 

[therichieboy]

Sounds like the cloth is the culprit. It has long been disposed of and next brew I'll check.
Thanks for the input.

 

[therichieboy]

Hi again. Thought I'd solved the issue; been a while since I saw pink. We lowered our dilution from 1 to 2% a few months ago. Then tonight again....pink!!
Any further insights?

 

[xanthippus]

My first suspect is still the cloth.

If it isn't, a little more info would help.

What was the reason for stepping up the PAA concentration?
What temperature do you run your CIP process at?
What other acids/acidic cleaners do you use?
Does the water come into the brewery from copper pipes? If so do you know the pH?

(Pink turning to purple could also be a Manganese thing, but I highly doubt that)

 

[therichieboy]

My first suspect is still the cloth.

If it isn't, a little more info would help.

What was the reason for stepping up the PAA concentration?
What temperature do you run your CIP process at?
What other acids/acidic cleaners do you use?
Does the water come into the brewery from copper pipes? If so do you know the pH?

(Pink turning to purple could also be a Manganese thing, but I highly doubt that)

We increased the concentration based on a recommendation from a brewery that use the same brand.

We use perform caustic cleaner and the pipes are all polypropylene- no copper.

The pH is pretty low- 5-6 if I recall correctly.

Your theory about manganese is interesting as we do use brackish desert groundwater that's been run through an RO filter then mixed back with 10-20% untreated groundwater. I've been trying to get a water analysis so I can treat it accordingly but nothing yet. As it stands we use no water treatment.

 

[xanthippus]

I still believe that a chemical reaction is unlikely to be the problem. I'm proceeding assuming this is an exception.

Can you post a picture of the color before and after recycling? Does the recycling involve neutralizing it with caustic soda?

I'm assuming you talked to the manufacturer of the PAA cleaner already. Do they send any indicator with the PAA?

 

[therichieboy]

I still believe that a chemical reaction is unlikely to be the problem. I'm proceeding assuming this is an exception.

Can you post a picture of the color before and after recycling? Does the recycling involve neutralizing it with caustic soda?

I'm assuming you talked to the manufacturer of the PAA cleaner already. Do they send any indicator with the PAA?

I'll send a pic when it next happens.

Caustic and peracetic never come into contact with each other. That said, a couple of us brew and bottle separately. We run caustic and rinse after bottling and next one brewing runs acid. No one's had the problem except me so maybe it's the guy using the fv beforehand...? I've never known mixing the 2 to create a colour.

As for contacting the supplier, no. There is a language barrier but I will try and get someone who speaks Hebrew to do so.

 

[EazyMcBreazy]

Could be the source of your equipment if it's not the highest quality Stainless.
Have you passivated all of the stainless operating surfaces?
PAA is a strong oxidizer and could be corrosive with the wrong material
If the PAA is running through polypropylene that could be a source if it sits.
I've certainly pulled green PAA through a copper chiller so i'll use iodine instead.
And with low quality stainless, PAA caused rust from sitting, to resolve that I've mixed phosphoric acid in the solution, tends to degrade slower.

I don't have experience with passivation for bottling equipment but I would recommend switching to iodine for packaging equipment. Depending on the hose material that should fine with PAA.

 

[therichieboy]

Could be the source of your equipment if it's not the highest quality Stainless.
Have you passivated all of the stainless operating surfaces?
PAA is a strong oxidizer and could be corrosive with the wrong material
If the PAA is running through polypropylene that could be a source if it sits.
I've certainly pulled green PAA through a copper chiller so i'll use iodine instead.
And with low quality stainless, PAA caused rust from sitting, to resolve that I've mixed phosphoric acid in the solution, tends to degrade slower.

I don't have experience with passivation for bottling equipment but I would recommend switching to iodine for packaging equipment. Depending on the hose material that should fine with PAA.

Interesting. You think it may be rouging? Our FVs came from China on the cheap so seems highly plausible.
That said, it was purpose built for use with PAA and would rouging happen so quickly? We've only been using it sporadically for 6 months.

We have a home made bottle sanitiser that uses a lot of PP so I'll definitely look into your idea of iodine. Thanks.