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You are here: Home --> Forum Home --> Brewing Forum --> Is it infected? --> Finding the Root Cause of an Infection

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flapjackcarl
Houston, TX
Posts


Alright, so I have just encountered 2 infections on two batches in a row. This brings me up to a total of three infections in my 4 years of brewing (the first infection occurred on a tripel I brewed about a month ago. I’ll try and detail what went on and what I plan to do about it. Any advice or wisdom on figuring out the culprit and preventing future infections is much appreciated

1.) Why do I think it’s infected. I don’t have any pictures, but I’ll explain as best as I can. I brewed two beers, beer A and beer B. Beer A was brewed a month ago, beer B was brewed 3 weeks ago. Both are in primary. I pulled my first sample off of each approximately 1 week ago. Beer B tasted great (clean flavor with good hop bitterness). Beer A tasted off. The flavor wasn’t overwhelming, but it didn’t taste quite right. I took another sample of Beer B last night. When I did this, I noticed that there were a good amount of bubbles sticking around the surface. Upon looking closer (through the carboy with a light), I noticed that these bubbles were quite oily in nature, different to anything that I’ve scene. After pulling a sample, I detected a new off flavor that was not present 1 week ago. I decided to go check out beer A (which had recently been dry hopped, cold crashed, and fined with Gelatin (dry hop happened last week on Tuesday, cold crash Saturday, gelatin Sunday). To my dismay, beer A had a partial film on top, along with the same groups of small but oily bubbles present in beer B. I have never seen anything like this on top of a beer that had been cold crashed and fined. This, coupled with the off flavors leads me to believe I’ve got an infection on my hands.

2.) So my first question is: where did this come from. I made a major process change on beer A and B: I upgraded to an oxygenation kit. I’ve been sanitizing this by boiling the stone, then dipping stone and tubing into sanitizer, then oxygenating. I realized that this method does not account for any potential for contamination from the regulator itself. The fact that 2 out of 2 beers brewed with this system came out infected has really led me to believe that this is the culprit. On the other hand, this issue doesn’t seem to present itself in CO2 systems. Additionally, I have this third beer from a month ago that came out infected. Could it be something else?

3.) If it is something else, what could it be. All of these infections occurred in primary, so it isn’t kegging or transfer related. My process (post boil) is as follows. I cool using an immersion chiller, typically down to about 120 F. I’ll then transfer through my kettle valve into a sanitized fermenter which I chill to pitch temps in an ice bath. Then I aerate (historically by shaking, recently by O2), and ferment in my mini fridge. Possible thoughts on infection are as follows

a. Ball Valve on Kettle: Unlikely. I disassemble before nearly every batch (and on both of the last two batches) prior to brewing. I clean and sanitize, then reassemble.

b. Transfer tubing: Unlikely. I use silicone tubing that I boil, and then sanitize for good measure.

c. Immersion Chiller: Unlikely. I place my IC into boiling wort for 15 minutes prior to chilling.

d. Scratched carboys: possible. I typically clean my carboys with an oxy soak followed by shaking a small amount of rice and water to remove krausen junk. This hypothetically could have scratched the carboy, leading to a crevice for a nasty to hide out in. On the other hand, these carboys have been used to brew noninfected batches very recently. This idea seems possible, but unlikely. I sanitize carboys by filling with 1 gallon of sanitizer solution and shaking for several minutes to make sure I get good contact with all surfaces

e. Infection during chilling: unlikely. My kettle is mostly covered during cooling. I also have not made any changes to this method throughout my brewing history

f. Minifridge: I’ve had some issues with mold developing in my minifridge. I try and clean this as much as possible, but periodically I will find some mold on the exterior of a carboy or on the walls of the fridge. I typically clean this off and don’t really worry: it’s outside the fermentation vessel and I’ve got a seal between the two.

g. Oxygenation kit: this is my best guess. It’s one major variable that changed between  previous batches and the last two. Perhaps that’s the culprit, and the third contamination was just a lapse in sanitation.

4.) How do I pinpoint the issue? I’m currently planning to mix up a batch of DME, boil it, pitch yeast, then aearate one by shaking and one with O2 to see what happens. This won’t yield results for 3 or so weeks, however. Any ideas on what I should do to prevent this?





Posted 34 days ago.

Stonehands
Charter Member
Birmingham, AL
59 Posts


Tell me more about the ball valve on your kettle? Weldless? Threaded? What kind of valve?

Aeration system- using those red oxygen canisters?




Posted 34 days ago.

flapjackcarl
Houston, TX
59 Posts


Threaded 2 piece ball valve. Stainless steel. Not concerned about that being the source. I disassembled it prior to each of the last brews, cleaned the valve and the threads on the nipple from the kettle. Sanitized and reasembled. 

The oxygen system is indeed the red benzomatic cannisters. Regulator and stainless steel wand/stone from williams brewing. If it wasn't for the tripel (my outlier), I'd be almost certain it's the oxygen setup. I'm really considering grabbing a packet of us05, mixing up some starter wort, and fermenting 4 batches in mason jars. One as a control with only shaking. One with shaking and aeration through my o2 system. One with shaking and a pitch of yeast from the starter I used (saved yeast from the starter), and one with shaking fermented open to atmosphere. If only the last shows signs of infection, that will narrow it down. 




Posted 34 days ago.

testingapril
Charter Member
Atlanta, GA
595 Posts


Two suggestions. One, mix your sanitizer a little stronger. Especially if it's star san. You can mix star san up to 2x the label directed strength and still be in compliance with the mfg. instructions if you look on the website. I mix mine at about 1.25x the recommended strength.

Two, try a few batches without o2 and see what you get. When I changed my oxygen bottle last time I found some nasty junk in the regulator, mainly rusty looking stuff, but I didn't get any infections. I'm back to shaking the carboy though.




Posted 34 days ago.

Stonehands
Charter Member
Birmingham, AL
59 Posts


In addition to the above, I'd try a couple of things. If you think it's the aeration system (those red cans are pretty sterile I believe fwiw) get one of those cheapo inline filters that they have at Williams with one of their other systems. Use it downstream of the regulator and oxy can. 
I still would look a little suspiciously at your ball valve. I know you've cleaned it well, but those threads can be pesky and they don't get as hot as you think they do being on the otside of your kettle. Can you manually dump your kettle next time and bypass the valve?




Posted 34 days ago.
Edited 34 days ago by Stonehands

ingoogni
nl
314 Posts


Do you make a starter? From What do you make a starter?




Posted 34 days ago.

flapjackcarl
Houston, TX
314 Posts


I'm typically pretty loose with my starsan dilutions. I'm almost certainly using starsan that is if anything, too concentrated.

In regards to the oxygen, I don't think it's the o2 itself. That's a pretty inhospitable atmosphere. I'm more worried it's either the outside threads of the o2 tank or the regulator.

Finally, on the ball valve..I'd be hard pressed to manually dump. I use carboys, so I'd need a larger funnel than I have. I could siphon, but that's one additional variable for cause. I reeeeeally don't think it's the valve. It's spotless. I also went infection free when I was way less scrupulous regarding the cleanliness of the valve. I won't right it off as of now, but right now I'm leaning towards scratched carboy from my rice method, o2 system, or my fermentation chamber






Posted 34 days ago.

flapjackcarl
Houston, TX
314 Posts


I do use a starter. I boil dme and water for 15 minutes. Cover pot with lid and cool in ice bath to 130ish. Wipe down exterior of pot and spray with starsan. I then pour starter wort through funnel to 1 gallon glass jug. After I get to 70 I pitch yeast and put it on a stirplate. I cover it with sanitize foil for its duration. I cold crash and decant before pitching. I checked saved yeast last night and saw no visible signs of infection.



Posted 34 days ago.

Stonehands
Charter Member
Birmingham, AL
59 Posts


Glass carboy? Doubt rice scratched it. Perhaps try cleaning with pbw and not oxy. Pbw from my experience does a little bit better job. Let it sit in there (hot water too) for a couple of days. 

I understand about dumping instead of the valve - it's a pain. I use glass carboys, but have one of those mondo funnels that sits in the neck without having to hold it. It was a good purchase honestly. I don't use a valve, have a kettle and not a keggle, and my funnel. Kills my back but I think it's fewer chances for nasties to grow. 

I'd try the $12 hepa inline filter on the oxy setup, peace of mind if nothing else. I really would try bypassing your valve for a batch - even if you have to buy the funnel. 

Sorry. Those infections can be tough to chase down. 




Posted 34 days ago.

testingapril
Charter Member
Atlanta, GA
595 Posts


Easiest way to rule out the ball valve is to run boiling wort out of it into a pitcher or something right before flame out and then just pour that back into the boil. do this a few times to heat sanitize the valve then flameout and chill quickly. Heat sanitize is very effective.




Posted 34 days ago.

flapjackcarl
Houston, TX
595 Posts


Plastic carboys actually. I hate glass. It's heavy and it breaks. Potentially scratching? It seems unlikely. Rice in water is a very mild abrasive. 



Posted 34 days ago.

Stonehands
Charter Member
Birmingham, AL
59 Posts


Hmmm, plastic carboys. Did both infected batches come from the same fermenter? Can you use a different one?
Never mind, just reread and you said both are in primary. 




Posted 34 days ago.
Edited 34 days ago by Stonehands

flapjackcarl
Houston, TX
59 Posts


Last use for those carboys would have been a schwarzbier and cal common that were reviewed here. No infections. Rice cleaning as a practice has happened since before those beers.



Posted 34 days ago.

flapjackcarl
Houston, TX
59 Posts


Also...would you reuse a carboy after an infection? If plastic. 



Posted 34 days ago.

Stonehands
Charter Member
Birmingham, AL
59 Posts


I probably wouldn't. To me, infection time means dumping all plastic and starting again. My brewdays are too few to try to save some of the more inexpensive gear. 



Posted 34 days ago.

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