Can mold come through my airlock?

[tomaso]

My last 8 or so batches all have the same slightly weird aftertaste and kind of spoil all those beers. I won't try to describe it as acidy, fatty, soapy or whatever because I simply don't know what it is. It's not strong, some people don't notice it and in IPAs it gets masked but it is noticable
I thought at first it was the yeast but it doesn't seem to be it and I somehow get the feeling that it must be some sort of infection.... which brings me to the topic of mold...

I had an unfortunate 'Teramisu spill' in my chest freezer earlier this year and even though I tried to clean it well and spray it with star san twice there still is some mold on the walls of the freezer after a while. I even had some on the ouside of the carboys a few times in summer. Now that the temperatures drop here in Spain also the mold lessens....
(see this thread https://www.homebrewtalk.com/showthre...=540582&page=3)

But my question is whether that mold has the power to creep through the airlock and/or bung into my beer? I thought that impossible but with that weird taste persisting and not being able to find any obvious fault in fermentation or other part of the process it might be that.... Thinking about it I also noted, I think around the same time, that my batches started having a sort of oily film on the surface at bottling.
Neither this nor the aftertaste are really bothersome or very off putting but I always notice it now, creeping in at the end of every sip and it shouldn't be there.

So do you think it could be the mold or should I look for another culprit? some other place of infection maybe?

 

[jwalk4]

I don't know for sure about the spores into the air lock.

But I would start scrubbing the walls of the chest freezer until ALL the mold is gone. Mold spores are everywhere naturally, but they can cause real off flavors if they are present where you ferment.

Do you store your brewing equipment in a damp area?

 

[odorf]

bleach 1 cup per gallon water kills mold
I use 100% bleach in a spray bottle when hunting mold
take no prisoners!!!!

maybe you have a leak around your bung,
are you sanitizing immediately before fermenting?
or are you sanitizing after you ferment, put on a shelf,
then use again ? on next ferment

I drop a couple of drops of water around the air lock /bung connection
just to ck for leakage.

 

[tomaso]

I don't know for sure about the spores into the air lock.

But I would start scrubbing the walls of the chest freezer until ALL the mold is gone. Mold spores are everywhere naturally, but they can cause real off flavors if they are present where you ferment.

Do you store your brewing equipment in a damp area?

I don't store my equipment in a damp area. It's really just the chest freezer itself and the contamination from the Tiramisu spill I think. As I've said, I've scrubbed and starsaned it twice and still some crops up but now I'll try odorf's suggestion with the bleach.
But my question actually was whether the mold could get past then bung and/or airlock because I don't think I have a leak there...

bleach 1 cup per gallon water kills mold
I use 100% bleach in a spray bottle when hunting mold
take no prisoners!!!!

maybe you have a leak around your bung,
are you sanitizing immediately before fermenting?
or are you sanitizing after you ferment, put on a shelf,
then use again ? on next ferment

I drop a couple of drops of water around the air lock /bung connection
just to ck for leakage.

I always sanitise before fermenting. I'll check about the leakage but I really don't think so as I use 4 to 5 different ferm vessels and I notice the flavour in beers coming from all of them.

So my question really is whether the mold can get past the bungs if there is no leak. If not I think I have to look for something else.
Anyway, now that it's colder here I'll get a new carboy and brew a batch in it and leave it outside and if that one comes out well I know it has something to do with the ferm chamber!

Thanks for all of your replies!

 

[Greatbreweh]

Air does get past any air lock, as the fermentation stops and there is a temp drop it pulls air back into fermenter through the airlock in opposite direction so that could introduce airborne mold spores.

And really addresses a good concern for all of us as I noticed black mold on my ac unit (not currently on this time year) inside fermentation chamber, I have a job to do this weekend.

Edit,

That got me concerned I could not wait went out hit ac unit with tilex.

 

[Bellybuster]

Do you keg or bottle? I had a very faint Mold like flavour and finally traced it down to the tap itself. There was beer stone in the tap that was causing the off taste. Once cleaned out flavour was gone

 

[Rev2010]

Air does get past any air lock, as the fermentation stops and there is a temp drop it pulls air back into fermenter through the airlock in opposite direction so that could introduce airborne mold spores.

This is incorrect information. Yes there's a chance of suck back if the temp drops too low or you lift a flexible fermenter such as a plastic one, but standing in place after fermentation is done the positive pressure ceases, it doesn't reverse and the slight lowering of temperature isn't enough suck back to pull in the liquid in the air lock and outside air.


Rev.

 

[Greatbreweh]

This is incorrect information. Yes there's a chance of suck back if the temp drops too low or you lift a flexible fermenter such as a plastic one, but standing in place after fermentation is done the positive pressure ceases, it doesn't reverse and the slight lowering of temperature isn't enough suck back to pull in the liquid in the air lock and outside air.


Rev.

Well my experience is in my fermention chamber my 18 Gal stainless Steel fermenters ( I have 3) suck 1 liter of fluid back every time ( from 2L coke bottle through silicone hose) as soon as fermentation stops, it was so bad that I went to simple carboy type airlocks so as to not suck so much sanitizer back into fermenters. Always happens every brew for over 100 brews.? My fermentation chamber never changes from 19-20 C

We are all learning the art.... and this is what I learned to be true.

I added the pic to show how much neg pressure there is to suck a liter of fluid up from the coke bottle on the ground to the top of these fermenters....Significant

 

[Rev2010]

Well my experience is in my fermention chamber my 18 Gal stainless Steel fermenters ( I have 3) suck 1 liter of fluid back every time ( from 2L coke bottle through silicone hose) as soon as fermentation stops, it was so bad that I went to simple carboy type airlocks so as to not suck so much sanitizer back into fermenters. Always happens every brew for over 100 brews.?

Strange. Maybe someone else can shed some light on why that is happening. I've only ever brewed 5G batches and used regular airlocks rather than blow offs as my fermenters have a good amount of headspace and never has the airlock liquid (I use vodka) ever sucked back in after fermentation. And I would easily know due to the amount and level in the airlocks. Only time I've ever had such back was when I forgot to remove the airlock and took a hydrometer sample and when the time or two I picked it up to move it with the airlock still in place.

There might be something else at play here causing this.


Rev.

 

[Greatbreweh]

Strange. Maybe someone else can shed some light on why that is happening. I've only ever brewed 5G batches and used regular airlocks rather than blow offs as my fermenters have a good amount of headspace and never has the airlock liquid (I use vodka) ever sucked back in after fermentation. And I would easily know due to the amount and level in the airlocks. Only time I've ever had such back was when I forgot to remove the airlock and took a hydrometer sample and when the time or two I picked it up to move it with the airlock still in place.

There might be something else at play here causing this.


Rev.

I have scratched my head many of days opening the chamber, I typically have 11-12 Gallons in the fermenters.

 

[catsnbeer]

I have scratched my head many of days opening the chamber, I typically have 11-12 Gallons in the fermenters.

That sounds totally weird! If theres no real pressure or temperature differential, then some kind of siphon could have somehow started? It's not cause you are dropping trub ,yeast or taking samples... I am sure you have considered that!

 

[marcownz747]

This is incorrect information. Yes there's a chance of suck back if the temp drops too low or you lift a flexible fermenter such as a plastic one, but standing in place after fermentation is done the positive pressure ceases, it doesn't reverse and the slight lowering of temperature isn't enough suck back to pull in the liquid in the air lock and outside air.


Rev.

This is also incorrect information. When fermenting, yeast doesn't JUST make CO2 and ethanol. Its third main byproduct is heat. Depending on the batch size, you could easily have a drop in temperature significant enough to reverse the pressure. At 1-5 gallons, this isn't terribly likely, but it's still possible.

Also, back pressure is possible if you're putting the beer in before it's hit the temp of your fridge. If you're planning on dropping a 70f carboy into a 50f fermentation chamber, or are planning on dropping a 50f lager into a 35f lagering phase, you could EASILY end up getting backwards pressure.

I've personally experienced this multiple times.

Scrubbing the mold out of your chest freezer/fridge would be a good start. When I run into a problem with mold or lacto, I scrub everything down AND sanitize it as thoroughly as possible. In average situations, you can get away with using a 2 in 1... but when you've got obvious mold or lacto, using a cleaner AND a sanitizer is needed.

 

[catsnbeer]

This is also incorrect information. When fermenting, yeast doesn't JUST make CO2 and ethanol. Its third main byproduct is heat. Depending on the batch size, you could easily have a drop in temperature significant enough to reverse the pressure. At 1-5 gallons, this isn't terribly likely, but it's still possible.

Also, back pressure is possible if you're putting the beer in before it's hit the temp of your fridge. If you're planning on dropping a 70f carboy into a 50f fermentation chamber, or are planning on dropping a 50f lager into a 35f lagering phase, you could EASILY end up getting backwards pressure.

I've personally experienced this multiple times.

Scrubbing the mold out of your chest freezer/fridge would be a good start. When I run into a problem with mold or lacto, I scrub everything down AND sanitize it as thoroughly as possible. In average situations, you can get away with using a 2 in 1... but when you've got obvious mold or lacto, using a cleaner AND a sanitizer is needed.

...yeah but the GreatBreweh said it didn't suck the 1 L into the fermentor until the END of fermentation. I would be surprised if the yeast induced drop in temperature after primary fermentation produced a temperature differential great enough to aspirate 1 L of fluid that high ... i mean the top of his fermentors are like 4 - 5 feet off the ground.

Could be the head pressure in the top of the fermentor - given the height of those conicals and the low location of the 2 L bottles - then when CO2 is no longer being vigorously produced, the residual pressure could be leaking out of the top opening/seal which would then aspirate the fluid from the blow off container...? or something ... Now I am scratching my head for you.

 

[catsnbeer]

Oh and for the OP... IMO it is unlikely that mold could enter through a functioning airlock ... unless of course you got suck back like was also being discussed! Contamination usually comes from accidental surface contact.

 

[Rev2010]

This is also incorrect information.

So I say a temp drop too low can cause suckback and you tell me my information is wrong and proceed to say a large temp drop can cause suckback - which is precisely what I said.

Regardless of suckback, who here doesn't find it odd that every one of his past 100 batches has sucked back in 1L of blow-off liquid?


Rev.

 

[Greatbreweh]

I am convinced it is temp drop, I was strongly trying to make my point earlier but truth is it happens more with 05 yeast as it seems to get a very aggressive fermentation going, likely raising temp of beer inside over ambient fermentation chamber 19-20 c.

Mind you I brew 80 percent with 05 yeast also.

My fermenters have very high quality silicone gasket and there is no leak from there as suggested.

I also know it happens with temp drop because I started cold crashing early brewing with this equipment and saw again coke bottle dry as sanitizer was sucked up so I know it is related to temp drops.

In fact while fermenting those carboy type airlocks ( u see in my picture ) can have all the sanitizer blown right out of them and I have to refill them several times, yeast really likes my setup it seems..

My real point was if I can have that much air draw back in I am sure if mold spores were present and airborne they could be drawn in.

 

[Rev2010]

I also know it happens with temp drop because I started cold crashing early brewing with this equipment and saw again coke bottle dry as sanitizer was sucked up so I know it is related to temp drops.

If you're cold crashing with the blow off or airlock still in place, especially without relieving the negative pressure along the way, then yes you'll definitely get suckback, that's just physics. But I thought you said you get suckback simply after fermentation has ended, in which case the few degrees of temp drop shouldn't be enough pressure drop to suck in 1L of blow-off liquid or sanitizer fluid. Not even my simple airlocks suck the small amount of fluid into my beer.


Rev.

 

[Singletrack]

11 to 12 gal in an 18 gal fermenter leaves a lot of head space. The more head space you have, the more compressible gas you have to contract upon cooling temperatures, and the more suck-back you will experience.

 

[Greatbreweh]

If you're cold crashing with the blow off or airlock still in place, especially without relieving the negative pressure along the way, then yes you'll definitely get suckback, that's just physics. But I thought you said you get suckback simply after fermentation has ended, in which case the few degrees of temp drop shouldn't be enough pressure drop to suck in 1L of blow-off liquid or sanitizer fluid. Not even my simple airlocks suck the small amount of fluid into my beer.


Rev.

Yes it is after fermentation i have been talking about, I just also mentioning that I saw it happen overnight few times when I specifically lowered temp before kegging.

 

[Greatbreweh]

11 to 12 gal in an 18 gal fermenter leaves a lot of head space. The more head space you have, the more compressible gas you have to contract upon cooling temperatures, and the more suck-back you will experience.

Now that sounds like a good possibility.

 

[tomaso]

Do you keg or bottle? I had a very faint Mold like flavour and finally traced it down to the tap itself. There was beer stone in the tap that was causing the off taste. Once cleaned out flavour was gone

I bottle and I don't think it has to do with the bottles themselves because that taste is already there when the beer is in the bottling bucket.

Oh and for the OP... IMO it is unlikely that mold could enter through a functioning airlock ... unless of course you got suck back like was also being discussed! Contamination usually comes from accidental surface contact.

Yes, I agree... I don't think the mold gets in either.

Another option might be the burnt stuff that I just scraped off my brew pot. Never really ocurred to me (Silly, I know) to remove it. it's the brown stuff that sticks to the bottom. Just scraped it off and now it's just metal again.
You think that could be it?

Anyway, I just brewed a small extract batch that I will leave outside the chamber cause it's cold enough now here in Barcelona and will see if that makes a difference. Will eliminate the factor of the chest freezer and any grain related issues.
I also left out irish moss but highly doubt that could be a factor....?

Thanks for all your help!

 

[Rev2010]

Another option might be the burnt stuff that I just scraped off my brew pot. Never really ocurred to me (Silly, I know) to remove it. it's the brown stuff that sticks to the bottom. Just scraped it off and now it's just metal again.
You think that could be it?

I've read that beerstone (that's what it's called) can indeed affect the flavor of your beer. I don't have enough experience with it to say personally however. By the way, I wouldn't recommend scraping it off as it's not good for the stainless. To remove mine I used StarSan sanitizer at 4x the strength used for sanitizing. Filled my kettle and let it sit for 30 minutes and the stuff rinses right off - though I still cleaned my kettle after for good measure. Here's a before and after pic:

Rev.

 

[tomaso]

By the way, I wouldn't recommend scraping it off as it's not good for the stainless.

Rev.

Too late! I've already scraped the hell out of it
Let's see how it affects this batch but at least I know now what it's called. Thanks

Your clean kettle looks so nice btw!