View Full Version : Pedio contamination in tank

10-30-2017, 09:57 PM
I pumped a barrel of bourbon barrel aged imperial stout into my 15bbl brite and noticed something off about the flavor. I then put it under the microscope and found that it was lacto / pedio. This was found in 2 of the 12 barrels.

I immediately dumped the tank, sprayed it out, tossed all gaskets and valve seats and filled the tank about half way with 200 deg water for about 5 hours hoping to pasteurize it, then dumped and took some swabs of different ports and areas and let them sit in some sterile thioglycolate and confirmed pedio. Here is what I did so far to kill it.

Trial 1:
-Caustic (shear250)/ manual scrub
-Acid (Acid #14)/ manual scrub
-Caustic / manual scrub
-Acid / manual scrub
-PAA 4x strength
-Took sterile swabs of the center drain and sight tube port and placed in thioglycolate. (Didn't have enough thio samples made at the time so only did those two places.

1 days later, both grew pedio

Trial 2:
-Got an ATP meter and tested various places on the tank. The top and sides came out to around 0 (beer only filled the bottom 10" of the tank) and the side ports, drain and sight tube ports read in the 60's indicating an issue.

- Manually scrubbed all problem sections, ATP tested, then repeated until clean.

-Repeat caustic / acid / PAA from trial 1

-Took sterile swabs from the following and placed in thioglycolate: 3x side ports, drain port, dish bottom, side wall low, sprayball, PRV port, door.

- 4 days later all tubes are completely clear except for the door sample.

Trial 3:
-Removed door, atp tested 2 different areas and got a high number in one location and relatively lower in others.
-Scrubbed the hell out of it sanitized then repeated until I got 0 and 6 on the meter. The tank is closed up and I will take more samples tomorrow.

Has anyone had any experience in killing this stuff and is there a better way? I feel like we have it narrowed down, but I'm never going to feel comfortable unless I literally swab every square inch of the tank. For the time being I have one pump and some hoses dedicated to this nightmare and all valves etc used in this are to be autoclaved and tested before they're useable again.

dick murton
10-31-2017, 07:45 AM
You're right, it can be a pig to clean up after some infections

Firstly, I suggest that autoclaving large lumps of metal and gasket will not be particularly effective, but if you strip all these small parts down into their constituent parts, manually clean every joint surface, you might have a chance of killing off every bug associate with those parts.

Similarly strip all the tank joints, clean and sterilise again before reassembling

I suspect that the pump and or hoses may be concealing some of the bugs.

If the pump is not specifically a hygienic design, and many people use good, but not specifically hygienically design pumps, then the gaskets and seals will harbour contamination. Even if your pump is supposedly hygienic, consider when it was last stripped down, cleaned and sanitised and fitted with fresh seals.

If the hose is not food grade, is old and / or starting to perish due to the material not being fully compatible with the cleaning / sanitising chemicals, then the degraded surface can harbour bugs. Similarly, if the hose is not connected properly to the tail, then bugs can remain in the minute gaps between the tail and the hose. If they are home jointed with jubilee clips or similar, then strip them apart, inspect the hose interior and if fit for re-use, i.e. as new, you could sterilise and refit, else replace the hose completely.

Finally, you are liable to have splashed the work area - floors, walls and vessel exteriors with the infected beer, no matter how careful you think you might have been. So hospital operating theatre hygiene standards apply here as well, until you have got rid of the bugs. Don't forget to include spanners etc. in this clean up

11-01-2017, 08:46 PM
I would do an acid/no rinse/caustic cycle using nitric/phos blend at a pH 2 or so concentration and caustic at 12.5 pH or higher then rinse. Id then follow with a 6 hour cycle of PAA between 614 and 2632 ppm. This is considered a anti microbial concentration for spartan chemicals (similar concentrations of PAA and H2O2 as most), however they suggest a temperature of 40-60*C for a minimum seven seconds contact time. They specifically list pediococcus damnosus, lactobacillus buchneri, and saccharomyces cerevisiae.

I personally would forgo the raised temperature in return for the six hour cycle as others have provided data that PAA is much more effective over prolonged periods. Six hours should be sufficient to reach a sterilization standard, especially at these concentrations.

During the long cycle, I would use a foaming acid agent and foam the entire exterior of the tank and surrounding areas. I would re-apply judiciously during the cycle ensuring the exterior remained wet with solution for close to the same six hour period. Then I would rinse with 82-92*C filtered brewing liquor starting outside and moving to the interior.

My biggest fear would not be the interior of the tank, but the exterior and surrounding areas. Its easy to re-contaminate if the bugs are still in the area.

11-06-2017, 07:39 AM
Good point about the exterior.

After 3 rounds of thioglycolate swabs we had narrowed it down to a point on the manway door. I removed the door and scrubbed the hell out of it with pure caustic, pure acid and pure PAA, then burned the hell out of every inch with a blowtorch, put the door back then did a 4x strength PAA cip and re-tested with thio.......and one part of the door still came back cloudy after 24 hrs. I haven't plated it or looked at it in the microscope yet, but I'm seriously thinking of just buying a new door for it. I understand that we're working with clean tanks as opposed to sterile tanks but i just cant see how there can be anything left. Again, this is just after filling a 15 bbl tank with 50 gal of infected barrel beer and dumping it immediately.

After mentioning the exterior I wounder if the door is becoming re-contaminated when its being opened for sampling.

dick murton
11-06-2017, 10:48 AM
you haven't said whether you have replaced the sealing rubbers with brand new, sanitised ones.

environmental samitisation - probably easiest, if not particularly pleasant, to manually clean as much as you can reach, then clean with foam - rent a foam unit for a couple of weeks, and then spray with PAA or other suitable food grade sterilant - not hypochlorite - effective though the stuff is, you want to have usable stainless kit at the end of this.

11-06-2017, 09:41 PM
Hinge pin hole? Scrubbed it with a little tap brush? Foam or flood your drain trenches?

Where on the door was this sample taken from? Is it possible you are getting splash back from the ground or drain? Sneaking out of the door hinge pin area? Cleaned the lunchroom fridge?

Good luck, and sincerely hope you can get it eliminated.