Airborne wild yeast

Hey all, I've been brewing for a few years now and the batches over the past year have all ended up with some sort of wild yeast issue. One of the problems is that it doesn't really show up until a couple months after brewing.. yay.

I just put my oatmeal stout in a keg and I tasted some of the beer out of the fermenter (put some in a glass during siphon) and I can once again detect a bit of the infection, we'll see if it shows up stronger later.

My last thought since I've eliminated so many variables is that I have a sort of house yeast that is present in the air/dust in the house. Now that I've had so many infected batches I would think it is possible. Has anyone else ran in to this?

Why do you suspect wild yeast? Plating?

I suspect a wild yeast issue due to an off flavor I get start getting after a month or so of the beer being finished. Also when I've done bottling every bottle becomes overcarbonated. It doesn't turn sour or tart, just off, some people have described it as apple.

The kegs also became overcarbonated after sitting for a while outside the fridge.

Why yeast though? As opposed to bacteria.

Not really sure it matters which, but I suspect a wild yeast because the beer doesn't taste bad, just off, and the speed of the infection, bacteria seem to work faster than that. Either way I want it to stay out of my brews.

Are you washing yeast? You would not expect that much airborne yeast this time of year unless you are doing other things (baking,microbiology lab) in your free time.

Can you describe the off-flavour? How about your standard sanitation procedure?

It happens sometimes with cheese making and it's called phage. They recommend changing cultures periodically and, of course, keeping equipment scrupulously clean.
Maybe you could try changing your usual yeast and only using boiled water.
Hope this helps.

The difference with brewing is that we are talking about yeasts, which are much more seasonal than bacteria. That is why I was wondering if the OP is washing yeast. If not, then I highly doubt recurring wild yeast. I am no cheese-maker, but "killer" bacteria sound much different than the slow, insidious growth of wild yeast in beer.

EDIT: Reading more about bacteriophage, I sure am glad we don't have viruses in beer! Sanitation would be a nightmare!

I do all of my brewing indoors, so I don't think the season would have anything to do with it. Since I've been having the issue I've been using brand new packs of S-05 yeast instead of any of the washed yeast. So about a year of using new yeast now.

I've been using star-san for sanitizing. I switched to no-chill as a way to try to get around this problem, but before that I had a CFC I would pump boiling wort through for the last 10 minutes to sanitize.

Kegs/bottles are cleaned with an oxyclean soak before being sanitized with star-san and in the case of the kegs, stored with some star-san in them.

We were making yogurt upstairs, but I tried to keep that separate from the brewing. I've never done a lambic. I have had infected beers spew out when opening them (near the brewery). I also do all my bottle cleaning in the same room as the brewery. Grains are stored and milled in a separate room.

The brew that is in the chest freezer now has yeast from a local brewery. I am wondering if the chest freezer has a mold issue (though I try to keep some desiccant in there) and when I put ~70 degree wort in there, and drop it to 64 I get some suckback... maybe pulling in some infection.

Thanks for any help you guys can provide... I gotta kick this thing or quit brewing

So you have had bottles gush out in the past? Was it the whole batch or random bottles? If you leave the beer in primary/secondary for a few months what does the top of the beer look like? The mould in the chest freezer will not get in if the carboy is covered.

Sounds like you have taken all the appropriate steps to clean before/after each brew. I am not sure that you even have an infection. Do you think you might have a problem with oxidation, what is you procedure for racking/bottling/kegging.

theredben said:

So you have had bottles gush out in the past? Was it the whole batch or random bottles? If you leave the beer in primary/secondary for a few months what does the top of the beer look like? The mould in the chest freezer will not get in if the carboy is covered.

Sounds like you have taken all the appropriate steps to clean before/after each brew. I am not sure that you even have an infection. Do you think you might have a problem with oxidation, what is you procedure for racking/bottling/kegging.

Click to expand...

Bottles I've had gush out were given to me by other homebrewers, just siting it as a possible source.

For me, the whole batch goes bad. The bottles get to a point where they foam heavily, and it takes 5-10 minutes to pour into a glass. The kegs I've left out (unconnected) also overcarb. The off-taste has been described by some others as "apple" though I find it hard to describe.

I had one beer (pumpkin ale) I left in primary for almost a year, it had gone bad and didn't feel like cleaning it up. It eventually got some white floaters, most of the time I don't see anything strange on top the beer before transfer, just normal krausen.

I was thinking of the chest freezer since I put an airlock on the carboy at ~70 degrees and then drop it down to fermentation temperature ~64, so I get suckback through the airlock. A little star-san isn't going to hurt the beer, but thought perhaps something else would get in.

This last brew (no-chill) I transferred to the carboy upstairs, then didn't start the chest freezer up until fermentation took off, that way I didn't get any suckback when I dropped it down to 64 for the remainder of fermentation.

Hey Con -

I suspect it is a bacteria problem, not a wild yeast problem. I had been having similar issues. All the beers tasted pretty good going into the kegs, however after some time in the keg (where the beers would usually improve with aging) I began to detect what I would describe as an apple-ish / pear-ish taste as well as more of an alcohol/hot presence. I finally figured out the problem: My (now retired...) old stainless 2 barrel fermenter. (There may be some pics of it in my gallery) It is dish bottomed, and came from the manufacturer with a sanitary 1.5" triclover tube welded to the bottom center (yeast / trub dump / drain). No problems there.

I had a stainless coupling installed on the side of the fermenter, above the trub line, used to transfer the beer into the kegs. Because of the shape and size (6' tall with only a 6-8" lid)of the fermenter, it could only be welded on the OUTSIDE of the fermenter. Therefore leaving a small gap between the coupler and the tank wall on the INSIDE of the fermenter. THAT'S where the problem is.... no amount of cleaning/sanitizing even using a brush on a handle could get all the critters out of that little gap.

It took me forever to figure out where the problem was as I am so anal about sanitation. It finally dawned on me to check that fitting with a flashlight through the lid. Also, it took a number of batches for the issue to begin presenting itself - at least a dozen good batches with that fermenter before each one started getting progressively worse.

I feel your pain, man, as it is EXTREMELY frustrating to go from making great beer to making not great beer....especially when you didn't change anything!

I now ferment 27 gallon batches in (2) modified Sanke half barrel kegs that I am CERTAIN the tri-clover connections welds are sanitary/ground and polished - inside and outside. (no pics yet on my gallery.) Also, I am able to steam sanitize them by placing on a turkey fryer burner with a few gallons of water and boiling the h@ll out of it for 30 mins or so while going about the regular brewing activities, which definitely kills everything as well as eliminates the need for chemical sanitizers.

Also, FWIW, I use a chest freezer for ferm. temp control and have had suckback into the fermenters due to temp changes, but haven't had a problem yet. I can see why you would consider this though...as I have had mold and funky smells in there when I accidentally spilled beer/wort in the freezer or even on the LID of the fermenter! However, knock on wood, no problems from that. It did however make me much more fastidious about wiping down and cleaning both the freezer and the fermenters!

Sorry to be so long winded here. I guess my advice to you is look for somewhere on your equipment that you are not able to be CERTAIN is getting cleaned/sanitized. Good luck and I hope you are able to fix the problem soon.

Thanks for the replies all. I'll continue to try to find where the problem is, I just wish it showed up quicker than 2-3 months after brewday.

Someone else suggested my ball-valve on the keggle, so I did a 45 minute idophor soak on that (turning the valve on and off a lot). But even then, I am currently putting boiling worth through it not only during recirculation, but also right in to the no-chill cube.

I may have to let the cube sit for a week or so next time to see if there is an issue in the brew room. So far I think I have it isolated to fermentation, as my last batch seemed to have a bit of the flavor even coming out of the fermenter (we'll have to see). Kegging system is all boil-sanitized now, so shouldn't be that anyway. If it warms up a bit, I'll do my brewing/fermenting/bottling out in my shop to see if I can get a good batch by change of location.

You guys have a good way to sterilize a (glass) fermenter? So far that's the only thing in the process that hasn't been boiled. Everything gets cleaned meticulously.

Bleach will "sterilize" it, but it needs a rinse with boiled, cooled water.

Are you using secondary fermenters and if so what are you using to transfer from the primary to the secondary? If you're using a plastic auto syphon it's possible you have some ickies hiding out somwhere in that or in the tubing you're using for transfer.

Also, how are your final gravity readings? Overcarbonation + apple to me sounds like your yeast isn't finishing its job and is not cleaning up after itself. Acetaldehyde (green apple flavor) is usually caused by rushing your beer. How are your pitching rates? What temperature are you fermenting at? Possible you're fermenting a bit too cold, stalling out the yeast, and then they wake up again when you bottle / move them out of your temperature control to a warmer enviornment? If you're rushing the beer off the yeast before it's done and then closing it up into bottles that could create the problem you're describing.