Recurrent infection in stainless steel fermenter

Brewing Processes
1

Hi,
I am posting this because I have read everything there was to read on the subject and I still can’t find the solution.
The only solutions that I will try right now are:

  1. Soak the fermenter overnight in 0,5% sodium percarbonate solution, then put the wort in.
  2. Buy and use Starsan or the European equivalent.

So, here’s the long story, short:
I brew in my kitchen, I mill the grains next to my fermenter, I think the grain dust fell into the fermenter.
I brew BIAB, then boil in a boil kettle. I chill with a stainless steel immersion chiller that is put in the wort in the last 10 minutes of the boil.
I only use bittering hop additions and post-boil, aroma hopstand additions at 140 degrees F or 60 degrees C.
Then I pour the chilled wort in the sanitized fermenter, put the lid on, which is an immersion chiller lid.
Prior to use, the fermenter is cleaned with detergent, rinsed, cleaned with caustic, sodium hydroxide, rinsed, dried. A half-hour or an hour before I put the chilled wort in, I fill the fermenter with percarbonate solution which I drain before I put in the wort.
The fermenter is an eight US gallon fermenter, European 30 liter stainless steel German fermenter with an immersion chiller lid. I use ice water to control the temperature. When the chiller is on and the pump pumps ice water in, then I get suckback and the vodka from the airlock gets sucked back inside the fermenter.
This is the fermenter:

This is the chilling lid:

Potential sources of contamination (may be more):

  • open kitchen window next to the chilled wort = the wind brings dust from the outside which falls into the wort
  • I squeeze the nylon bag with the hops in the hopstand when I pull it out = bacteria from my “sanitized” hand falls into my chilled wort
  • the fermenter is not fully disinfected from the half-hour/one hour percarbonate soak, the chilled wort gets infected from the inside of the fermenter
  • the wort inside the fermenter gets infected from the air sucked back in through the airlock when the chilling occurs
  • the yeast is infected because I sprinkle the dry yeast in a flask with boiled and chilled water, covered with aluminium foil, which is put in the fridge. Maybe the air in the fridge is full with bacteria and it gets in the water with the yeast, and I pitch bacteria in the wort with the yeast.
  • the wort gets contaminated from the two ball valves of the fermenter
  • the air conditioning that sits above the fermenter gets air with bacteria in the fermenter when the lid is off, before I put the wort in
  • I get the infection in the beer when I open the ball valve and pour a sample for the hydrometer
  • I get the infection in the beer when I put water in to top it off, and get from 4 US gallons to 5 US gallons; the water I use to top off is boiled and chiller and kept in a plastic bottle.

Lastly, the infection occurs at day two of active fermentation. In the first day, the airlock esters smell ok, in the next day, they smell off. When I open the lid to see the infected beer, a very strong acrid, sour, tart smell comes out. The beer pH is 4. I only brew ales. Yeast is S-04, US-05, K-97, S-33 etc.

So this is all. What do you think I should do?
Right now I will make a small beer just to try out the overnight percarbonate soak, to see if it works.
If not, I will buy Starsan and use that. But if the first solution and Starsan don’t work, I give up.  :-\

2

Try removing and boiling your ball valves?  It is the most likely source that comes to mind based on you sanitizing regimen.  Lastly, don’t let your fermented beer sit long before packaging and storing cold.

Best of luck on ridding your system of this critter issue. Some are downright pernicious. Cheers!

3

Is the fermenter new?  Have you ever fermented an uninfected beer in it?  My thought is dirty ball valve(s) or crud in the cone dump tube.

Have you ever considered cooling the wort to pitching temp before transferring to the fermenter to prevent suck back?

4

I did unscrew the spigot, which has a ball valve and boiled it 15 minutes closed, 15 minutes open. Then in percarbonate solution for 30 minutes. So I think I managed to salvage that one. The other ball valve, on the bottom, is impossible to remove, I think. It’s just a pipe with a lever on top of it. It can be uscrewed, the lever, but I can’t get a screwdriver that small to do that. And I don’t think that makes it so that the ball valve can be removed. It’s not a tri-clamp.
I did pour boiling water on top of it and let it sit. My bet is that the boiling water will kill the bugs in that lower valve. And the overnight percarbonate.
The last brew I did, which was a success before this infection, was a wheat session beer. It fermented in one day. I let it sit for three days in the fermenter and then bottled. So, yes, I am not planning to let the beer sit too long in the fermenter. One week, max.

That beer is fully carbed and has no off flavours at all. It is one of the best beers I have made. Belgian witbier with pilsner malt and wheat. I have no idea why that small beer did not infect and this last one, which was one at which I worked on a lot, was infected. I do have one idea now that I think of it. That small beer had a British yeast that was not only very flocculent, it also stuck to the inside of the fermenter and that cooling steel coil, which is a pain to clean. I cleaned it with dish washer liquid detergent, then sodium hydroxide. I did see that the dried yeast was stuck to the inside of the spigot. I cleaned it with a brush. So the yeast dirt was stuck even after the sodium hydroxide treatment.
So… yes, that yeast sediment might have been left behind somewhere, stuck to the steel somewhere I couldn’t get to it or see it. In a nook or cranny. But that’s exactly why I started using sodium hydroxide, to get rid of that dirt.
The yeast I am talking about is Fermentis S-33. It sticks like glue to stainless steel and is as hard as a rock and extremely difficult to clean after fermentation.
Now I am thinking of putting boiling water in the steel fermenter as a rule.

5

The fermenter is not new. I did ferment the first three beers from kits, the last was infected. Not fully, but I did get some off flavours. Then the next two were infected, then one was ok, then yesterday, infection, again.

Dirty ball valves… I did think of this. I can’t unscrew them, though. Will try to post pictures of them. Maybe they can be pulled out.
But I thought that if you leave enough sanitiser enough time, overnight in my case, then it will solve even this problem.

The wort is cooled to about 86 F, 30 C before I put it into the fermenter. Then I put the Inkbird at 18 degrees C, 65 F and that’s when the suckback occurs. When the yeast goes wild and starts fermenting and producing heat, then the pump is turned on to keep the temperature at 65, that’s when the suckback occurs. Because the ice water pumped inside the fermenter is much colder. So, during the active fermentation.
I was thinking of putting a blowoff tube in a jar of vodka to solve this. But I think this will only mean more suckback of vodka.
I don’t 100% think that the suckback is the problem, because it just sucks in air from the kitchen. And I don’t think that could be the cause of the infection. But it could be…

6

[quote]I brew in my kitchen, I mill the grains next to my fermenter, I think the grain dust fell into the fermenter.

[/quote]

Start by eliminating this.

[quote]Then I pour the chilled wort in the sanitized fermenter, put the lid on, which is an immersion chiller lid.

[/quote]

How do you clean and sanitize this? Is the IC lib also your fermentation chilling method? These are hard to get clean and you have to be extremely meticulous.

7

Agreed.

This is one of the first things I would look at if you can get the valve apart.  I had a ball valve on my kettle, before I changed it out to a butterfly valve, and took it apart after every few brews to inspect it.  Even though I ran hot PBW through the system (kettle, pump, and plate chiller) after the brew day to clean it, I would always find crud in the shell of the ball valve when I disassembled it.  The cleaning method did not remove it since it is harder to get cleaning solution into this area of the valve, even with the pump.
There should be some way to get it apart unless they welded the valve in place (highly unlikely since it would damage the valve seals).  They had to put it together, so it should come apart.

8

Start by eliminating this.

[quote]Then I pour the chilled wort in the sanitized fermenter, put the lid on, which is an immersion chiller lid.

[/quote]

How do you clean and sanitize this? Is the IC lib also your fermentation chilling method? These are hard to get clean and you have to be extremely meticulous.

[/quote]

Agreed.  Grain is often said to be a source of lactobacillus.  Mill as far from the fermentation area as possible.

9

Good point: I don’t even like to measure out grain in the brewery (aka laundry room) because it stirs up grain dust. I like to mill in the garage.

10

@ majorvices

I’ll try to mill the grains one day before or keep the fermenter completely sealed when I mill, then open all the doors and windows to make an air current, to remove all the dust from the air.

About the internal cooling coil, I clean and disinfect it the same way I do the fermenter.
Here is a picture of the fermenter with 30 liters of percarbonate before I drain it and put in the wort:

11

This is the picture of the bottom of the cilindroconical stainless steel fermenter:

You can see the two ball valves.
The top one, I boiled. I did unscrew the top lever, but I could’t pull the ball valve out.
I couldn’t get the bottom one open because I could’t fit a screwdriver there. So I am only using boiling water on that one.

12

It sounds like you are using something like One Step no rinse cleaner.  While it does have somer sanitizer properties, I’d definitely recommend adding a real sanitizer to your routine.

13

Yes, sodium percarbonate is One Step cleaner.
PBW is also percarbonate, but with sodium metasilicate, which is a very powerful detergent from what I read.

So, yeah, I was thinking this also, to use the percarbonate for the cleaning part and the Star San for the disinfection part.
I’ll try and see how it works out.

14

Yes, clean, the sanitize.

15

Consider using iodophor rather than StarSan.  It can be more effective than StarSan at killing wild bacteria.

16

Before I filled the fermenter with percarbonate I used to fill it with iodophor, iodine to 25 ppm with citric acid in water. It didn’t work. I still had infections. I know for sure that it doesn’t kill bacterial spores.
With the percarbonate I did manage to brew without infections. Maybe one hour is not enough. Maybe overnight will do the trick. I did read that some guy from New Zealand or Australia always uses percarbonate overnight and never has infections. That’s why I am willing to give it a try. And the stuff is cheap.

If it doesn’t work, then I will use percarbonate, then star san. This should kill the bacteria because the first is alkaline, the second is acidic. Both are disinfectants.

17

You should use both.  Sanitizers are rapidly inactivated by organic solids.  As hopfenundmalz said, clean, then sanitize.

18

Correlation does not equal causation. Just because he told you that he never had an infection may or may not be due to his process.  Quite frankly, a brewer that says they never had an infection is suspect IMO.

For what it’s worth, I’ve had an infection using Star San but never with Iodophors.  …but I blame it on the cleaner (both the product and the laborer).

Always mix BTF Iodophor into cool or lukewarm water.  The hotter the water, the faster the Iodine will gas into the atmosphere.

Mix rate:
1/2 ounce (14.7 ml) concentrate per 5 gallons of water;
1/4 ounce (7.39 ml) concentrate per 2.5 gallons of water;
1 tsp (4.92 ml) per 1.5 gallons of water.

Things that will degrade the solution:

-Residual alkaline detergents.  The Iodine complex and the Iodophor concentrate are acidic solutions.  Mixing into any water that has residual alkaline detergent will neutralize the solution.

-Excessive agitation or shaking

-UV light, so leave your solution in a dark place

Using iodophors with citric acid is not the normal usage regime. It not killing bacteria could be because you misused it and have nothing to do with effectiveness.

19

I have only used star san (as a homebrewer) for the last … I dunno at least 15 years, and have never had a (homebrew) infection during that period. I am a meticulous cleaner which is far more important than sanitizer anyway. You can think of sanitizer as just a “precaution”. Totally agree with the “clean, then sanitize” statements.

For me, oxi-clean soak, light scrubbing, good rinse and star san works every time. Anything difficult to sanitize gets either boiled or at least “flash boiled”.

I have had infections when the fermenter wasn’t sealed properly and air has made it’s way in (such as a dry airlock).

Obviously, being a commercial brewer, I have a different approach completely for professional applications. But sanitation issues on the home brew scale are usually due to careless cleaning or overlooking something vital (like a ball valve). It is so damn easy to keep everything clean and sanitized that if a homebrewer follows close attention to detail it simply shouldn’t ever be a real problem - even with simple star san.

20

I knew as soon as I typed that someone would say they’ve never had an infection. [emoji23]