Uh oh. Wild yeast? Infection?

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Beersmith gives a slightly different number sometime and I have a wort correction number for my refractometer.

Just a PSA here... I know some folks think of the wort correction factor (WCF) as a factor unique to their refractometer, and I've read articles written by people who should know better that implied that. But that's not the real purpose. A properly operating refractometer shouldn't need a unique one (for the particular instrument) . The real reason for the WCF is that refractometers are designed to measure sucrose concentrations, and the sugars/dextrins in wort are mostly not sucrose. And since sugar/dextrin profiles are different for each wort, ideally each wort would have its own WCF applied. In reality, most people use a single WCF for everything, maybe one that seems to give them the smallest error on average. What they are really chasing there is their own average wort.
 
So is it dangerous to store unfermented wort?
If the wort has not been sterilized, then yes it is dangerous.

Will it be sterile enough to stay fresh and safe for more than a year?
Regular wort boiling at 212F at ~ 1 atmosphere will not sterilize wort and it will not stay fresh or safe for a year.

What if the malt or the hops were contaminated with C. Botulinum?
The spores could germinate, C. Botulinum could grow, and you could die from drinking it.

Boiling alone cannot deactivate the spores, that takes 250f+
Agreed. That's why anyone who makes wort for starters should use a pressure cooker and sterilize the wort at 250F (at 15 psi above atmospheric pressure) for at least 15 mins. Only when the wort and its container have been sterilized (not just boiled and sanitized) by pressure canning in sealed mason jars will it keep fresh for a year.

yet this not an uncommon practice.
I would hope people are only using these bags for the time it take ~ 5 gal of wort to cool from 212F to room temperature and are pitching yeast immediately and not using them to store wort for weeks.

It's true that nothing grows in beer will kill you because of the pH and alcohol content of finished beer, but stuff that grows in unfermented wort certainly can kill you. Death from food-borne botulism is fairly rate (something like 500 cases in the last 50 years), but it can still make you sick. The CDC says:
Many outbreaks of foodborne botulism in the United States result from eating improperly preserved home-canned foods. Persons doing home canning and other food preservation should
be educated about the proper time, pressure, and temperature required to destroy spores
 
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Just a PSA here... I know some folks think of the wort correction factor (WCF) as a factor unique to their refractometer, and I've read articles written by people who should know better that implied that. But that's not the real purpose. A properly operating refractometer shouldn't need a unique one (for the particular instrument) . The real reason for the WCF is that refractometers are designed to measure sucrose concentrations, and the sugars/dextrins in wort are mostly not sucrose. And since sugar/dextrin profiles are different for each wort, ideally each wort would have its own WCF applied. In reality, most people use a single WCF for everything, maybe one that seems to give them the smallest error on average. What they are really chasing there is their own average wort.
Thanks for the information. I should change the WCF in beersmith I put that in there 3 refractometers ago when I got my first one. I normally use a spreadsheet (seanterrill) to track my SG and not beersmith. I doubled check the spread sheet it does not have a correction factor. The final numbers are usually pretty close like 1 or 2 gravity points to the hydro but I really use it more to determine activity than the actual gravity.
 
If the wort has not been sterilized, then yes it is dangerous.


Regular wort boiling at 212F at ~ 1 atmosphere will not sterilize wort and it will not stay fresh or safe for a year.


The spores could germinate, C. Botulinum could grow, and you could die from drinking it.


Agreed. That's why anyone who makes wort for starters should use a pressure cooker and sterilize the wort at 250F (at 25 psi above atmospheric pressure) for at least 15 mins. Only when the wort and its container have been sterilized (not just boiled and sanitized) by pressure canning in sealed mason jars will it keep fresh for a year.


I would hope people are only using these bags for the time it take ~ 5 gal of wort to cool from 212F to room temperature and are pitching yeast immediately and not using them to store wort for weeks.

It's true that nothing grows in beer will kill you because of the pH and alcohol content of finished beer, but stuff that grows in unfermented wort certainly can kill you. Death from food-borne botulism is fairly rate (something like 500 cases in the last 50 years), but it can still make you sick. The CDC says:

When I read the article posted by @Beermeister32 I immediately thought about the
LalBrew Köln dry kolsch yeast. That yeast takes days to get going from the time you pitch. In the article I think it said botulism needs under 2 percent oxygen to grow, I wonder if that should be ppm.

Fresh boiled wort should have a low oxygen content but If you aerate the wort prior to pitching the yeast would that provide enough oxygen for a few days to keep the botulism at bay?
 
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That yeast takes days to get going from the time you pitch.

It depends what you mean by "get going." Even before you get to high krausen, the yeast is acidifying the wort in its exponential growth phase. It needs the pH gradient to transport nutrients across its cell membrane and (helpfully to us and it) out compete other organisms by creating a low-pH environment. I'd have to check my brewing texts, but the pH drops pretty quickly from 5-ish to 4-ish and ultimately to the high threes for ales. And since pH is a logarithmic scale, one unit is really a factor of 10.
 
Thanks @duncan.brown. By "get going" I mean there is no visible fermentation activity. Even when pitched at proper amounts it can take days before it showing active fermentation(krausen and CO2 generated). If it grows like all other yeasts it seems like that delay might be an issue.
 
Thanks @duncan.brown. By "get going" I mean there is no visible fermentation activity. Even when pitched at proper amounts it can take days before it showing active fermentation(krausen and CO2 generated). If it grows like all other yeasts it seems like that delay might be an issue.

Here's an article written for the home brewer by someone with a background in microbiology:

http://suigenerisbrewing.com/index.php/2020/01/29/botulism-in-beer/
tl;dr there's nothing to worry when home brewing about unless you store unsterilized wort in sealed containers for extended periods of time or try and capture wild bugs without pre-acidifying the wort.

Here's an interesting article in Frontiers in Microbiology where a group studied the growth and evolution of the organisms in lambic over time and shows the influence of pH on the organisms present:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6252343/
 
This thread has inspired me. I just brewed a new batch, with the usual sanitary protocol. But found myself with plenty of extra wort, of decent-enough gravity, so I decided to try to brew a "wild small beer": I covered that second bucket with a cheesecloth and will wait to see what happens...

We must have all kinds of yeasts and bacteria floating around in the countryside, as we often make spontaneously-fermenting kvass and other stuff. It's never failed. And we're still alive.

If it smells good, I'll drink it. I'll post an update just to reassure folks I haven't died of botulism. All for science.
 
This thread has inspired me. I just brewed a new batch, with the usual sanitary protocol. But found myself with plenty of extra wort, of decent-enough gravity, so I decided to try to brew a "wild small beer": I covered that second bucket with a cheesecloth and will wait to see what happens...

We must have all kinds of yeasts and bacteria floating around in the countryside, as we often make spontaneously-fermenting kvass and other stuff. It's never failed. And we're still alive.

If it smells good, I'll drink it. I'll post an update just to reassure folks I haven't died of botulism. All for science.
Remove the cloth until it started to ferment! You can also put it outside to catch whatever the wind carries.
 
Remove the cloth until it started to ferment! You can also put it outside to catch whatever the wind carries.
It’s only one layer of very open mesh fabric - I thought it would help to keep away the flies, cat hair etc. I usually use a cheesecloth with kvass and other spontaneous fermentation. Do you think it’s important to keep it fully open?
 
It’s only one layer of very open mesh fabric - I thought it would help to keep away the flies, cat hair etc. I usually use a cheesecloth with kvass and other spontaneous fermentation. Do you think it’s important to keep it fully open?
Depends. Kvaas has other stuff in it that already carries yeast. Wort really needs stuff from the air so you might at least want to let it sit in the open for some hours next to some trees or flowers or whatever might contribute to stuff in the wind.
 
This thread has inspired me. I just brewed a new batch, with the usual sanitary protocol. But found myself with plenty of extra wort, of decent-enough gravity, so I decided to try to brew a "wild small beer": I covered that second bucket with a cheesecloth and will wait to see what happens...

We must have all kinds of yeasts and bacteria floating around in the countryside, as we often make spontaneously-fermenting kvass and other stuff. It's never failed. And we're still alive.

If it smells good, I'll drink it. I'll post an update just to reassure folks I haven't died of botulism. All for science.
You should be good, an open fermentation is not anaerobic, there is plenty of O2 in and around the wort. :mug:
 
Depends. Kvaas has other stuff in it that already carries yeast. Wort really needs stuff from the air so you might at least want to let it sit in the open for some hours next to some trees or flowers or whatever might contribute to stuff in the wind.
I did as you suggested and - we have ignition! Less than 24h after brewing. Nice activity and buildup on top of the wort. Doesn’t smell particularly yeasty at this point.

I like to believe that all the relevant bugs are already floating around in the house. We’re in a log cabin with plenty of natural ventilation in a field next to a forest. And there’s lots of fermenting of assorted kinds happening during this season. Mostly the wife pickling stuff or experimenting with weird types of kvass/gira with whatever is at hand. My last beer batch has a suspicious aroma of a cross-contamination of some sort of lactobacillus…
 
I did as you suggested and - we have ignition! Less than 24h after brewing. Nice activity and buildup on top of the wort. Doesn’t smell particularly yeasty at this point.

I like to believe that all the relevant bugs are already floating around in the house. We’re in a log cabin with plenty of natural ventilation in a field next to a forest. And there’s lots of fermenting of assorted kinds happening during this season. Mostly the wife pickling stuff or experimenting with weird types of kvass/gira with whatever is at hand. My last beer batch has a suspicious aroma of a cross-contamination of some sort of lactobacillus…
That sounds like the perfect environment for wild fermentation! Just don't bottle this in normal manner..... This stuff will continue forever to ferment.
 
Ya, I agree with @Jayjay1976 , how does it taste or smell!?!? have we come to a consensus that it was wild yeast? Did you take another gravity reading to see if it reached the FG?

Also, IMO I love refractometers for the ease of use and small sample sizes. I do about 3 gal batches and taking hydrometer samples really drains my bucket. I love BeerSmiths internal conversion, makes everything easy and in my experience it is pretty on point, thats of course if there is no operator error involved. I usually take like 2-3 readings with their own separate samples, especially with the fresh wort off the stove. If you don't mix the fresh wort it tends to get a really f-ed up readings.

Use the calculators, but even more so understand what goes into the calculators. Knowledge is power my friend. It has saved me a ton of money on buying needless products which are all over the brewing market.
 
Bugs can and do. :mug:
I guess I do understand that it would ferment longer. I don't know why I said that. But honestly if the gravity hadn't stabilized yet I would never bottle.

I did that once with a summer shandy which oddly reached FG and I was holding it in the fermentor until I had time to bottle. Then a day or about 1.5 days go by then the fermentation took off again. I was extremely worried I had a contamination and for some stupid idea I thought that pulling it off the yeast and bottling it would stop the bacteria fermentation or whatever was causing the refermentaiton. Had a party to "tap the keg", but really bottles, and a few of them turned into bottle bombs. Luckily I tend to carbonate my beers high so I immediately pour the bottles into glasses, but as the night progressed and alcohol began to take effect friends would open bottles not pouring it and have a slow emitting volcano of foam. Fun fun
 
That sounds like the perfect environment for wild fermentation! Just don't bottle this in normal manner..... This stuff will continue forever to ferment.
Let’s see what happens… I usually bottle any weird and wild stuff in PET plastic bottles, to be safe. And drink it very young. They are gushers!
 
This thread has inspired me. I just brewed a new batch, with the usual sanitary protocol. But found myself with plenty of extra wort, of decent-enough gravity, so I decided to try to brew a "wild small beer": I covered that second bucket with a cheesecloth and will wait to see what happens...

We must have all kinds of yeasts and bacteria floating around in the countryside, as we often make spontaneously-fermenting kvass and other stuff. It's never failed. And we're still alive.

If it smells good, I'll drink it. I'll post an update just to reassure folks I haven't died of botulism. All for science.
Update: (Not on the OP's wild yeast infection, but on my own very first crude and deliberate attempt at open/wild fermentation, inspired by this post - see above)

I got pretty decent activity in my open bucket after 24h, with plenty of krausen building up. I let it ferment for a few more days and bottled in PET plastic 1L bottles, for safety. The wort did not give off the usual yeasty smell, but it was not unpleasant, either. Clearly there was plenty of fermentation still going on, because the bottles puffed up rock hard after a couple of days. Even after refrigerating, the bottles gushed almost uncontrollably.

The result? Nothing smelling or tasting like (normal) beer. I took a whiff and a few sips. It had what I would describe as a sanitized hospital ward smell. Something like isopropyl alcohol. Perhaps like the band aid smell folks sometimes identify in brettanomyces. I dumped the whole small batch (it was just over 4L/1G of leftover wort from my "real" brew). If I was in prison or in a desert island I could see myself drinking it. It did not have a nasty taste, but definitely not good either. Is it likely that I just got a pure brett brew? On a positive note, I'm still very alive. :)

On a final note, can anyone point me to a good guide to help recognize and identify the most common "off flavors" (that can also be intentional components of some beers)?
 
Update: (Not on the OP's wild yeast infection, but on my own very first crude and deliberate attempt at open/wild fermentation, inspired by this post - see above)

I got pretty decent activity in my open bucket after 24h, with plenty of krausen building up. I let it ferment for a few more days and bottled in PET plastic 1L bottles, for safety. The wort did not give off the usual yeasty smell, but it was not unpleasant, either. Clearly there was plenty of fermentation still going on, because the bottles puffed up rock hard after a couple of days. Even after refrigerating, the bottles gushed almost uncontrollably.

The result? Nothing smelling or tasting like (normal) beer. I took a whiff and a few sips. It had what I would describe as a sanitized hospital ward smell. Something like isopropyl alcohol. Perhaps like the band aid smell folks sometimes identify in brettanomyces. I dumped the whole small batch (it was just over 4L/1G of leftover wort from my "real" brew). If I was in prison or in a desert island I could see myself drinking it. It did not have a nasty taste, but definitely not good either. Is it likely that I just got a pure brett brew? On a positive note, I'm still very alive. :)

On a final note, can anyone point me to a good guide to help recognize and identify the most common "off flavors" (that can also be intentional components of some beers)?

Wild brews need time. They really need a lot longer then "normal beers". The reason is, that they are going through stages and these stages do not taste pleasent. If you would have waited longer, chances are high that other yeasts/ micro organisms would have taken over and either got rid of the off flavour causing components or masked them or whatever else might have happened there. The earliest wild beer I have ever heard of was ready for botteling after 3 months. But much more common is 6 to 12 months or longer. I have a wild mead here that started to be drinkable after 1.5 years and continually gets better and better..... so next time, give it wayyy more time.

But if it REALLY tastes like vomit, crap whatever, something went wrong, dump it.
 
Wild brews need time. They really need a lot longer then "normal beers". The reason is, that they are going through stages and these stages do not taste pleasent. If you would have waited longer, chances are high that other yeasts/ micro organisms would have taken over and either got rid of the off flavour causing components or masked them or whatever else might have happened there. The earliest wild beer I have ever heard of was ready for botteling after 3 months. But much more common is 6 to 12 months or longer. I have a wild mead here that started to be drinkable after 1.5 years and continually gets better and better..... so next time, give it wayyy more time.

But if it REALLY tastes like vomit, crap whatever, something went wrong, dump it.
Thanks for the feedback! I am really just dipping my toes into this wild world, and I will take this into account next time. Unfortunately time is something I did not have on this occasion, since we are about to leave the location where we spent most of the pandemic, and would not be able to carry the brew, nor have anywhere appropriate to store it for the coming months. I've learned a thing or three... and will be better prepared next time!
 
Thanks for the feedback! I am really just dipping my toes into this wild world, and I will take this into account next time. Unfortunately time is something I did not have on this occasion, since we are about to leave the location where we spent most of the pandemic, and would not be able to carry the brew, nor have anywhere appropriate to store it for the coming months. I've learned a thing or three... and will be better prepared next time!

If you have a nice and tight plastic fermenter like Speidel or similar, that would be best. It leaves through micro doses of oxygen, which is good in this case, but not as much as a bucket. Once you have this brew going, you can easily put it somewhere in the back of the basement and forget about it for a year. The only thing you have to take care of, is that the airlock is not drying out, so check every month or two. So if you know that you are going to stay for longer at one place, you can start :)
 
Update: (Not on the OP's wild yeast infection, but on my own very first crude and deliberate attempt at open/wild fermentation, inspired by this post - see above)

I got pretty decent activity in my open bucket after 24h, with plenty of krausen building up. I let it ferment for a few more days and bottled in PET plastic 1L bottles, for safety. The wort did not give off the usual yeasty smell, but it was not unpleasant, either. Clearly there was plenty of fermentation still going on, because the bottles puffed up rock hard after a couple of days. Even after refrigerating, the bottles gushed almost uncontrollably.

The result? Nothing smelling or tasting like (normal) beer. I took a whiff and a few sips. It had what I would describe as a sanitized hospital ward smell. Something like isopropyl alcohol. Perhaps like the band aid smell folks sometimes identify in brettanomyces. I dumped the whole small batch (it was just over 4L/1G of leftover wort from my "real" brew). If I was in prison or in a desert island I could see myself drinking it. It did not have a nasty taste, but definitely not good either. Is it likely that I just got a pure brett brew? On a positive note, I'm still very alive. :)

On a final note, can anyone point me to a good guide to help recognize and identify the most common "off flavors" (that can also be intentional components of some beers)?
I would suggest the book titled Yeast: The Practical Guide to Beer Fermentation by Chris White and Jamil Zainasheff. I haven’t read the whole book, I use it more as a reference book whenever I have questions or troubleshooting. They go in depth into the science of yeast before talking about very specific applications and processes behind brewers yeast. They even have a whole section of home brew versions of lab scale quality control tests for yeast. I haven’t read these sections in depth but they do have two subsections of the book on brettanomyces and “Capturing Wild Yeast”

the book is one part of a four part series from the Brewers Association on the four main beer ingredients. I also have For the Love of Hops: The Practical Guide to Aroma, Bitterness and the Culture of Hops from the great Stan Hieronymus.
 
I would suggest the book titled Yeast: The Practical Guide to Beer Fermentation by Chris White and Jamil Zainasheff. I haven’t read the whole book, I use it more as a reference book whenever I have questions or troubleshooting. They go in depth into the science of yeast before talking about very specific applications and processes behind brewers yeast. They even have a whole section of home brew versions of lab scale quality control tests for yeast. I haven’t read these sections in depth but they do have two subsections of the book on brettanomyces and “Capturing Wild Yeast”

the book is one part of a four part series from the Brewers Association on the four main beer ingredients. I also have For the Love of Hops: The Practical Guide to Aroma, Bitterness and the Culture of Hops from the great Stan Hieronymus.
I have the book, though not with me at the moment. I found it fascinating, though heavy on the science and less so on the "how tos".
 
If you have a nice and tight plastic fermenter like Speidel or similar, that would be best. It leaves through micro doses of oxygen, which is good in this case, but not as much as a bucket. Once you have this brew going, you can easily put it somewhere in the back of the basement and forget about it for a year. The only thing you have to take care of, is that the airlock is not drying out, so check every month or two. So if you know that you are going to stay for longer at one place, you can start :)
I may do as you suggest, Miraculix! The cellar is in my mother-in-law's house, in a little town in Lithuania. It's not temperature controlled, but it is cool and somewhat stable. It may go down to 10C in winter and 18C in a summer heatwave. I'm thinking of starting it off in a bucket in our house, then transferring to a carboy and "lagering" it off in her cellar for a year, until we're back next summer. Will that work? I'm sure she'll be good at monitoring the airlocks (I'm already leaving several 5L carboys of different meads with her!)

I still have many questions... Is hopping important (other than for taste), or can hops get in the way, since you're actually trying to get the wort "infected"? Is a "raw" (unboiled) wort a good idea, since it can pick up yeast from the unpasteurized mash? This will be my final "Covid-brew" before returning home, with my last remaining supplies. I think all I have is a few kg of Maris Otter. It will have to do... I realize I don't have much to lose, and will have something to make me look forward to visiting the mother-in-law!
 
I have the book, though not with me at the moment. I found it fascinating, though heavy on the science and less so on the "how tos".
Ya you’re right it is a bit heady. But honestly if you invest the time and understand a brief general info of the science, it will go a far way. If you understand the background you will understand how the yeast will behave and be able to make judgements on your own.

in absence of how tos, I have found and come to this forum! Tremendous help!
 
I may do as you suggest, Miraculix! The cellar is in my mother-in-law's house, in a little town in Lithuania. It's not temperature controlled, but it is cool and somewhat stable. It may go down to 10C in winter and 18C in a summer heatwave. I'm thinking of starting it off in a bucket in our house, then transferring to a carboy and "lagering" it off in her cellar for a year, until we're back next summer. Will that work? I'm sure she'll be good at monitoring the airlocks (I'm already leaving several 5L carboys of different meads with her!)

I still have many questions... Is hopping important (other than for taste), or can hops get in the way, since you're actually trying to get the wort "infected"? Is a "raw" (unboiled) wort a good idea, since it can pick up yeast from the unpasteurized mash? This will be my final "Covid-brew" before returning home, with my last remaining supplies. I think all I have is a few kg of Maris Otter. It will have to do... I realize I don't have much to lose, and will have something to make me look forward to visiting the mother-in-law!
Sounds good!

Mash is naturally held at pasteurisation temperature, there is basically nothing left to culture so nothing to win from this side. Just boil as usual.

Hops are important, even if they are not. Traditional Belgian Lambics are hopped with "aged" hops. They have lost most of their antimicrobial properties, but still have a bit left so that they can be used to limit the sourness a bit. Because this is what a beer without hops becomes, it becomes sour. Either through lactic bacteria, which do not need oxygen and convert sugar into lactic acid, or by acedic acid bacteria which can turn alcohol into vinegar, but these guys need oxygen. Lactic acid bacteria cannot tolerate hops, so you can stop the souring by using enough hops in addition to limiting the oxygen contact. Smaaall doses of oxygen might be beneficial, but these doses will get into the fermenter with time anyway if made out of plastic, so no action to be taken.

So you can either not hop and get something very sour, hop a little, let´s say 3-10 ibus and hope for the best (might still turn out very sour, or not sour...) or you can hop like a "normal" beer and possibly get something not (so) sour. A certain twang based on the wild yeast might appear, or it might not, that is the beauty of it.

You might want to add a bit of wheat (flour) to the grist, at least this is what the belgian guys are doing. 20-30% flaked wheat or wheat flour is not unusual. If you already have a basemalt shortage, this should come handy for you.

Good luck!
 
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