Wild yeast infection sources

I've done a lot of reading on the forum over the last few days re: wild yeast infections. I am pretty sure my last two batches got hit. The flavor is only slightly off. But both beers are gushers. Drinkable but certainly not my finest efforts.

I am fairly certain I got bit in the bottling stage. Both beers tasted and smelled fine at bottling. Now I've got gushers and some fruity esters that were not there at packaging.

I have gone over my equipment and sanitation process and nearly everything is in order. I think I have identified my two most likely culprits.

Suspect A - I found a cut in the transfer hose I attach to my auto-siphon. The hose, of course, has been replaced.

Suspect B - old priming sugar. I accidentally over-bought some corn sugar several months ago and had a 2 pound sack sitting in a ziplock bag in a closet. Shortly after that, I went through a kegging phase and the bag of sugar has been sitting (room temp and dry) in the closet for at least 6 months.

As with most problems, I think the infection here could have been a result of me taking a shortcut on bottling day.

While making my priming solution, I only just brought the solution to a boil, then removed it from the heat where it cooled while I sanitized the bottles, priming bucket, etc.

Is it possible that I got some wild yeast into this old sugar, then did not boil it long enough to kill all of the wild yeast? If so, how long is long enough to boil the priming solution. I usually only boil it 2-3 min max and have never had a problem. But this time, it seems like I just got it to a boil and left something living in the priming solution.

Either that, or it came from the cut in my tubing. Or a little of both.

Is it possible that your beer did not finish fermenting? Beer that is fermented at higher temperatures and/or was poorly aerated will lead to fruity esters in the beer...so is it possible that you bottled and stored in a warmer area?
Also are you using a bottling bucket? If so, the spigot is a great source of hiding bacteria.

I wouldn't worry about the priming sugar, any boiling at all will kill off anything growing there. Bottling bucket might be a place to look. The cut in the tubing is a possibility, but assuming you sanitized it there wouldn't be a lot of wild yeast in there so I would think it would take a while for a small population of wild yeast to take hold and cause gushers/esters.

Not finished fermenting is another possibility. I've had a couple of batches that definitely had esters develop over the course of carbing and cooling that weren't nearly as noticeable in the hydrometer samples. If you were a little bit estery to begin with and left a few fermentables behind, that could lead to your problem. Is the whole batch estery/gushing, or is it just a few of the bottles?

Per my notes, I was actually a couple of points lower than my expected FG on both beers. Both beers also fermented a couple of degrees warmer than I wanted and the one with the biggest problem (a stout) spent a month in primary in the same room where the bottles were eventually condition. The reason that I went with infection is that the problem was a sudden onset after several good batches.

I would be surprised if the spigot was an issue. While I am soaking the bottles in starsan, I usually disassemble the spigot and toss it in with the sanitizing bottles. Then I attach the spigot to the bottling bucket and fill the bottling bucket with sanitizer. Once it's set about 10 min or so, I drain the starsan through the spigot.

Everything that touches the beer (bottles, caps, wand, spigot, bucket, tubing, autosiphon) gets a starsan bath of 10 min or longer on bottling day.

I inspected the wand, autosiphon and bucket and did not see any obvious gouges or scratches that would harbor infection. Honestly, since I have already replaced the tubing, I can get a new bucket, wand, siphon and spigot for less than the cost of my next batch of beer. I am considering just pitching it all and replacing my whole bottling setup.

I do use a bench capper. One thing I never considered, what about the removable brass and magnet piece? I have never taken that off. Could that be a source of infection? My cap is usually wet with starsan when I load it in the capper so I don't worry about it. Should I be removing the metal and magnet piece and sanitizing that on bottling day as well I wonder?

I think your procedure sounds fine and I'd look at the plastic as the main culprit. You're probably fine with the old sugar, you just might want to boil it for 5-10min next time. I wouldn't worry about the capper or really anything else.

Did you remove the bottle labels? Probably a silly question, but a very important step.

Replace all the plastic and see what happens next.

I have been recycling the same bottles for years and don't use labels. I am a low frills operation. After bottling I mark each cap using a sharpie with the brew date and a code identifying the beer.

I've heard of some people using the sanitizing cycle on a dishwasher to clean their plastic. I assume they mean WITHOUT the heated dry? Has anybody here done this? I am particularly interested as to whether the autosiphon, spigot and wand will stand up to it.

Back when I was bottling, I used to put my bottles in the dishwasher to sanitize them... then I got some infections... so I bought StarSan. And then kegs.

It sounds like you have a perfectly acceptable sanitation regime for bottling. No need to worry about the sugar, you boiled it. The cut in the hose is possibly a source of bacteria/yeast but if you are running sanitizer through it, that was likely not an issue.

What you have described does not sound specifically like contamination post-bottling. You can have a few thousand bacteria/wild yeast/mL during fermentation and not notice it, but when it comes time to bottle the contamination finally has a chance to shine. Are you re-using yeast? I would look for something earlier in the process.

theredben said:

It sounds like you have a perfectly acceptable sanitation regime for bottling. No need to worry about the sugar, you boiled it. The cut in the hose is possibly a source of bacteria/yeast but if you are running sanitizer through it, that was likely not an issue.

What you have described does not sound specifically like contamination post-bottling. You can have a few thousand bacteria/wild yeast/mL during fermentation and not notice it, but when it comes time to bottle the contamination finally has a chance to shine. Are you re-using yeast? I would look for something earlier in the process.

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Not reusing. This was a fresh vial of WLP002 in a 1200ml starter. I made the starter about 48 hours before brewday. The flask was sanitized with star san as well. I boiled and cooled the starter wort, poured into the flask using a sanitized funnel. I hit it with O2 and put it on my stir plate.

I'm really scratching my head on this one. With the exception of the hose, all of my plastic looks to be in good shape.

*EDIT* The starter mentioned above was for the first of two affected beers. The second beer was the same yeast (WLP002) but also a new vial as well. The starter size for the second beer was about 1L. The flask and anything that came into the starter went through the same sanitation procedure mentioned above.

One other variable I just thought about. I use a SS wand to push O2 into my starters and my beers. I usually will give it a 20-30 min starsan soak before using. Then drop it back into the starsan afterward while I am cleaning up. Then it will just air dry until the next time I need to sanitize and use it. Is that the recommended way of working working with the O2 stone mounted on the wand? I have heard some people boil them. Should I do that next time? I figure just boiling the stone end in a saucepan of water for 5-10 min should be fine. The SS wand should be OK with a starsan soak.

If you are not re-using yeast that excludes the major source of contamination left. How much priming sugar did you use? Hydro readings the same 3 days apart? What was the temp of the beer when bottling?

Both beers had stable hydro readings over almost a week. One beer was in the primary for 3 weeks. The other was in the primary for just over 2 weeks. Both beers were at ambient room temperature the whole time, including the conditioning period (70F more or less). The stout was given enough sugar that it should have been around 2 volumes (right at about 3 ounces per the calculator I was using). The bitter was carbed with 1.3 ounces for 5 gallons at 70F, shooting for just less than 1.5 volumes.

The stout gushes at serving temps above 45F. I can keep it from gushing if I pour it cold and let it warm up before I drink it. It releases enough CO2 to form a hell of a head as it warms though.

The bitter has been in the bottle just 2 weeks. It does not gush yet, but it's got a tart flavor to it and it puts off enough CO2 in the glass to look more like a highly carbed lager or wheat beer than a bitter.

**EDIT** Both beers received corn sugar from the same already open sack.

Sounds like it may be slight contamination. I would drink them quick, and keep doing what you are doing with regards to sanitation. Hope it doesn't happen again.

I noticed you used wlp002 for one (or both?) of the batches.

You may have seen one of my rants about bottling with this yeast somewhere around here, but I've pretty much given up bottling with this yeast. I don't know if this strain is prone to infections in the bottle or what, but often when I bottle with this strain I will get gushers and a tart flavor. Not sour or nasty, like an apple cider tartness. I always assumed it had something to do with adding priming sugar and the yeast reactivating. I even went so far to replace all my plastic, threw out all my old bottles and bought new ones. I sanitize with fresh Starsan and even once tried baking the bottles in the oven to really ensure they were sanitized... and the batches with wlp002/1968 still got that off flavor. Since then I've gone to kegging and I have not had any problems with my wlp-002/1968 batches.

Edit: Another thing, the bottles always seemed fine for the first two weeks or so but then suddenly changed for the worse. The sudden change makes me think it could be yeast related, as I don't think an infection would completely change the flavor and carb levels within a few days.

@bierhaus15

Both beers used WLP002. I had 2 vials, from the same lot. Both only a few weeks old by the "best by" date on the vial.

1. Gushers - check on both beers
2. Tart Flavor - check on the bitter (sadly, I brewed the bitter after reading the extensive British beer 64/68/64 ferment schedule from the other thread I have noticed you on recently)

The stout has a banana ester to it, but I knew that was coming. I had to ferment at room temp, which is higher than I was shooting for with that one.

I have only bottled with this yeast one other time and I do not recall having this problem then. Any other time I have used it the beer was kegged.

On the bitter, after reading the other thread, I ALMOST cold crashed it and bottled with US-05. But at the time I bottled the bitter, the issue with the stout was just starting to rear its head.

I replaced the one tube that needed to go anyway, I am going to give my bottling bucket another once over, and probably a good bleach soak for the bottling bucket and spigot. The bottling wand and autosiphon will get a bleach soak and a trip through the sanitizer cycle of my dishwasher as well.

I'll brew a non WLP002 "cheap and easy" beer, maybe something summery for my wife and bottle with the heavily sanitized gear. If I get bit one more time, I will pitch the plastic pieces of my bottling gear and replace them.

theredben said:

Sounds like it may be slight contamination. I would drink them quick, and keep doing what you are doing with regards to sanitation. Hope it doesn't happen again.

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The bitter is new in the bottle (only 2 weeks after a 2 week primary). I am hoping it matures better but am not holding my breath. If I pour the stout cold and let it warm up, it keeps gushing to a minimum. but I am powering through both batches quickly