Ask The Brewmasters

This message was posted by a user wishing to remain anonymous

Hello all,

The QA team at our brewery recently started doing warehouse audits that include popping keg caps and inspecting the keg valves.  They found that many of our kegs contained a good amount of mold.  After scrubbing keg valve after keg valve to ensure the product in the warehouse was clean, we changed some programming on our keg line to increase the duration of steam sterilization and rinsing on our keg valves before they come off the line.  Additionally, we removed a pressure purge that existed at the end of the run to ensure there is enough pressure in the keg to seat the valve properly and avoid any chances of a leaker.  Since these changes, we haven't seen any mold issues with our kegs, however paranoia has its hold on me.  I've instructed my packaging crew to start spraying a light amount of 70% isopropanol in the keg valves prior to capping.

My question is, would anyone recommend a certain chemical for this?  Obviously the first step was ensuring our sanitation programming is sufficient.  But I'm looking at this as a backup.  70% isopropanol seems like a good choice; however, the high concentration makes it less economical.  We've considered PAA and sanadyne, but those both have their shortcomings (both personnel safety and frequency of mixing chemicals).  If anyone has a recommendation for an economical surface sanitizer for the keg valves that also doesn't hinder foam or flavor, I'm all ears.

Thanks in advance for your advice!

It's my understanding that isopropanol is not food safe, and therefore should not be used in situations where it may come into contact with beer. If you want to spray an alcohol, I would use 70% food grade ethanol (not denatured).

I think an phosphoric acid-based sanitizer would work fine for this as well, and ought to be significantly less-expensive than alcohol.

However, I think the best option is just to rinse well after filling. Whatever small drips carry over after the coupler/filler is removed can support the growth of mold, but if rinsed well enough, that should prevent mold growth

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Jonathan Hughes
University of California Davis
Woodland CA
(208) 244-4919
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Hello!

Our packaging crew uses an iodophor called LFI.

Best of luck!
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Garreth Austin
Quality Specialist II
Maine Beer Co
Freeport ME
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Agree, iodophor works like a champ for this application, I also understand this may not be practical on an automated line!

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Jeff Biegert
NBB Sponsored CSU Fermentation Science & Technology Faculty & Brewmaster
Lean Six Sigma Black Belt
New Belgium Brewing Co
Fort Collins CO
(970) 221-0524
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Original Message:
Sent: 03-24-2025 14:01
From: Garreth Austin
Subject: Recommended Chemicals for Keg Valves

Hello!

Our packaging crew uses an iodine and acid solution called Dyne-O-Might. 

Best of luck!

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Garreth Austin
Quality Specialist II
Maine Beer Co
Freeport ME
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Hi Anonymous, your choice of isopropanol (or ethanol) 70% is the best option since they quickly evaporate. Other no-rinse sanitizer solutions will leave moisture in the keg neck. You really want the neck to be as dry as possible when the plastic dust cap is applied. If you are not using vented keg caps, consider changing - you do not want a tight seal. Any residual moisture or condensation needs to be able to evaporate and dissipate. 

Feel free to call me to discuss further.

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Jon Graber
Sales Manager, Packaging Division
Micro Matic
Portland OR
(817) 403-1502
Micro Matic
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We really struggled with this problem for a long time. The problem with most sanitizers is that they break down with time, basically turing into water. There will always be a little soil in the neck behind the locking snap ring, and moisture + soil = mold. We tried using 70% isopropyl, but our audits found that after several weeks in storage, it did not evaporate and the keg necks still smelled like rubbing alcohol. I agree that using food-grade ethanol would be a good solution, but I belive the best solution of all is to just get the keg necks dry before you put the caps on. A quick burst of compressed air works well, and so does a firm wipe with a clean, terry-cloth rag.


Original Message:
Sent: 3/24/2025 1:08:00 PM
From: Jon Graber
Subject: RE: Recommended Chemicals for Keg Valves

Hi Anonymous, your choice of isopropanol (or ethanol) 70% is the best option since they quickly evaporate. Other no-rinse sanitizer solutions will leave moisture in the keg neck. You really want the neck to be as dry as possible when the plastic dust cap is applied. If you are not using vented keg caps, consider changing - you do not want a tight seal. Any residual moisture or condensation needs to be able to evaporate and dissipate. 

Feel free to call me to discuss further.

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Jon Graber
Sales Manager, Packaging Division
Micro Matic
Portland OR
(817) 403-1502
Micro Matic
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Given the fact that you are facing black mold indicates that a combination of residual moisture and airborne spores in the storage area are causing the mold.  This is likely accelerated by capping and retaining the moisture.  Several posters recommended Iodophor, however, I strongly recommend against using Iodophor.  Halogens are severely corrosive on stainless steel when allowed to sit and dry and this would cause pitting over time. PAA is not a great candidate either since the shelf life is limited.  Food Grade Isopropanol would be an option but would also quickly evaporate and not protect you from airborne spores and mold from condensation as the kegs are sitting there.

I would suggest a quaternary ammonium compound in this application.  Choose a neutral one and QAC are highly effective when fighting black mold in cellars.  I have applied this successfully in several breweries and it has worked like a charm.

Cheers,

  

    

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Dirk Loeffler
Executive Vice President
Technical Operations
SEKA Chemicals
(404) 600-1910
loeffler.dirk@sekachemicals.com
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