Salvaged moldy wee heavy, unsure what to do next...

[Smaug]

Hey all! Been brewing for a few years and never run into this before.

tl;dr no fermentation followed by mold, salvaged what I could by siphoning from the bottom, planned to pitch new yeast, but the salvaged portion appears to have begun fermentation on its own. Should I bother pitching new yeast?

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So, I cooked up a wee heavy and pitched yeast like normal. The smack pack didn't swell after breaking the nutrient packet, but I gave it a shot anyways.

There was no fermentation by the end of day 2 in the carboy, so I ordered some rescue yeast. Some time midday day 3 there was clear mold growth:

I picked a clear spot on the surface and stuck the racking cane in, siphoned from deep in the carboy, and left the top ~1.5in to avoid the mold if possible:

Well, since there was no fermentation for three days followed by mold, I assumed I didn't have any viable yeast and would need to pitch again, but morning of day 4 the salvaged portion appears to be fermenting without any additional yeast:

At this point I'm unsure whether or not to pitch. What do you wizened experts think is the most likely scenario - some of the old yeast finally woke up, and I can save the second round of yeast for a new beer? I've got some other fermenter in there? If the latter, would pitching new yeast to compete with whomever's taken up residence be advisable?

 

[Kent88]

I'd dump it.

There is still mold in there, you just siphoned out from under the surface formations. There are still mold cells in the liquid. Some mold produces some noxious stuff.

 

[Miraculix]

There is still mold inside and all the toxins that have been already produced are in there as well. Dump it, this is not safe to drink. Mold toxins can give you anything from headache to cancer. It's not worth it.

 

[Smaug]

Thanks guys! Sad to see it go, but better safe than sorry.

 

[IslandLizard]

Thanks guys! Sad to see it go, but better safe than sorry.

Yeah, very sad indeed! Yet, the best course of action.

Please, make yeast starters from now on. You never know viability of a pack of yeast until you make a starter. At the same time you also ramp up cell count, which is never a luxury anyway, and if possible, overbuild it somewhat so you can save some out for a next beer. 3 improvements in 1 single process.

Good wort aeration, or better yet, wort oxygenation, becomes more important for higher gravity beers. A super fresh yeast pack with 100-125 billion cells is not even enough to properly inoculate a 5 gallon batch of 1.040 wort. Picking up fresh yeast that was packaged last week (or even last month) is very rare.

BrewUnited's Yeast Calculator

 

[IslandLizard]

Any clue what caused the rapid mold infestation?
Insufficient cleaning and sanitation?
What sanitizer did you use?

I've seen beers sitting for several days without visible activity, eventually getting taken over by bacteria, or even wild yeasts, but never developing mold that quickly.
The super large headspace (containing air, oxygen) surely didn't help prevent it.

Mold spores in your transfer tubing perhaps?

 

[Miraculix]

Mold only grows if oxygen is present. Keep your fermenter air tight and the problem will not appear.

 

[Ridenour64]

Not to Hijack your thread, but, would there be an obvious/ noticeable off flavor even if he tried to salvage this beer? I have always fermented In stainless steel and never had the luxury of seeing my beer ferment. What are the chances that some of my batches have had something grow (other than yeast) and I just didn’t know about it?

 

[IslandLizard]

Not to Hijack your thread, but, would there be an obvious/ noticeable off flavor even if he tried to salvage this beer? I have always fermented In stainless steel and never had the luxury of seeing my beer ferment. What are the chances that some of my batches have had something grow (other than yeast) and I just didn’t know about it?

Effects of mold on one's health were addressed by @Kent88 in post #2

If there was any mold growth you probably would have seen it when cleaning your SS fermenter.

I've never had mold grow on my beer, even in earlier times when I didn't know squat about brewing and the need of making yeast starters (I must have skipped that chapter).

One of the worst examples was my 2nd brew, a Bohemian Lager, in which I had pitched a single vial of WLP802. It showed neither any visible signs of fermentation, nor infection or mold, sitting in a glass carboy for a week, alas, at 56F. At that point I just pitched a rehydrated pack of US-05, thus becoming a "Steam Beer." It turned out not too bad, actually.

 

[IslandLizard]

Mold only grows if oxygen is present. Keep your fermenter air tight and the problem will not appear.

If there's no fermentation, that (huge) headspace remains filled with air, containing 21% oxygen, not helping the case.

 

[Smaug]

Any clue what caused the rapid mold infestation?
Insufficient cleaning and sanitation?
What sanitizer did you use?

I've seen beers sitting for several days without visible activity, eventually getting taken over by bacteria, or even wild yeasts, but never developing mold that quickly.
The super large headspace (containing air, oxygen) surely didn't help prevent it.

Mold spores in your transfer tubing perhaps?

Honestly I'm not sure what caused the rapid infestation - I've been brewing with this setup for +/-10 years without a hitch. Transfer tubing does seem like the most likely culprit, if only because it's a little more challenging to clean and dry throughout the interior. I've always used sodium percarbonate as my sanitizing agent.

Interested in your thoughts on the large headspace, though! This is what I've been doing for 5-gal batches for some time, now, but I take it you would recommend a smaller fermenter? Can't say I'd complain at the thought of more manageable glassware...

 

[IslandLizard]

I've always used sodium percarbonate as my sanitizing agent.

There most likely lies your problem. It's not a sanitizer. It's a good cleaner.

Cleaning and sanitizing are 2 different things, 2 separate steps. Clean first, sanitize right before use.

How about using Starsan? That is a dedicated sanitizer. As long as the surface remains wet with it, it remains sanitized.
A 16oz, or a more cost effective 32oz container of concentrate will last many, many years. It took me 7 years to use up 32 oz.
The working solution is stable for weeks, months even.

 

[IslandLizard]

Interested in your thoughts on the large headspace, though! This is what I've been doing for 5-gal batches for some time,

Large headspace:
If that's a 6 or 6.5 gallon carboy, judging by the relatively large headspace left, it doesn't look like you have anywhere near 5 gallons of wort/beer in there.

The larger headspace should not cause problems generally, when fermentation takes off fast, or within reasonable time.
With good applied sanitation, the larger headspace should not be a problem either.
But when mold spores are around, the extra oxygen in the headspace only helped them. Due to the long lag of the old yeast, the pH of the beer probably never dropped fast enough either, also allowing mold to get a foothold.

Batch volume:
To get 5 gallons of beer when packaged (kegged or bottled), you would probably target for 5.25-5.5 gallons into your carboy, leaving about a half a gallon to a gallon of headspace depending on the size/volume of your fermenter. That way you can leave 1-2 quarts behind in the carboy with the yeast/trub.

Now, only if you transferred very clear wort, without lots of trub, from your kettle to the fermenter you can hope for only 1 quart of beer being left behind with the yeast/trub when packaging. 2-3 quarts left behind is much more common.

Either way makes good beer, you're just a bit low on volume from what it looks.

Mold and sanitation:
But volume is not the real issue here, it looks as the lack of proper cleaning and sanitation allowed mold spores to be left behind or develop somewhere. As you said, that vinyl tubing may well be the culprit. Definitely inspect it and see if you can trace the origin of the mold to that. Regardless, I'd definitely replace it, cheap insurance!

There are long draw brushes that are meant to clean inside various tubing.

Good cleaning is very important. As is good sanitation. Then make sure things dry thoroughly, especially the inside.
I drape my tubing and hoses over the corner of a storage rack, with the ends hanging down, so they can drip out on both sides and dry.

Now the mold could come from other areas too...
Do you have a kettle valve?
Are you using buckets with a spigot, such as bottling buckets?

 

[IslandLizard]

[...] but I take it you would recommend a smaller fermenter?

No, 6-6.5 gallons is perfect for 5-5.5 gallon batches, I don't think size is the problem at all.

[...] Can't say I'd complain at the thought of more manageable glassware...

Yeah, I hear you!
Large glass carboys are a bit of a pain to handle, especially when full. And they're dangerous too, they can break, leaving large sharp shards, which can cause severe injuries.

Definitely treat and handle them with respect. Carry with a BrewHauler or inside a crate, which gives you handles and a decent support. They're still a bit unwieldy though, especially when full (and heavy).

There are PET (plastic) carboys in that 6-6.5 gallon size, as well as (brew) buckets and all kinds of other fermenters.
One example is the Fermzilla All Rounder which has lots of charm from what I've read. It's still being updated, the later ones now feature thicker walls.

 

[Miraculix]

Headspace only gets problematic if the fermenter is not air tight. Once the fermentation is starting, all the co2 being produced pushes out all the air in a short amount of time and then you have the headspace filled with co2. If you don't open the fermenter and the fermenter is really tight, no oxygen can get in. But if you open the fermenter or transfer into another vessel (secondary), then the headspace becomes problematic.

 

[Yooper]

Headspace only gets problematic if the fermenter is not air tight. Once the fermentation is starting, all the co2 being produced pushes out all the air in a short amount of time and then you have the headspace filled with co2. If you don't open the fermenter and the fermenter is really tight, no oxygen can get in. But if you open the fermenter or transfer into another vessel (secondary), then the headspace becomes problematic.

That's sort of true, but the headspace will never be 100% co2, and oxygen can get in as fermentation slows. Oxygen can even ingress through the liquid in airlocks, the plastic airlock, etc- but it's not that much. It will happen in time, not usually very much in just a couple of weeks.

The thing is, the problem here is that there was inadequate yeast added and fermentation never started.

 

[Smaug]

Thanks for all the advice - been using sodium percarbonate for years and never knew!

Sounds like I've got my marching orders: replace tubing, deep clean, order some proper sanitizer.

I do use a plastic bottling bucket, but the spigot gets disassembled and components cleaned individually between uses.

 

[IslandLizard]

Thanks for all the advice - been using sodium percarbonate for years and never knew!

Sounds like I've got my marching orders: replace tubing, deep clean, order some proper sanitizer.

I do use a plastic bottling bucket, but the spigot gets disassembled and components cleaned individually between uses.

Add 30% of TSP/90 (Sodium Metasilicate, get a bag in your hardware store) to your Percarbonate and you've essentially created (homemade) PBW. The Metasilicate gives the Oxiclean an extra boost cleaning surfaces, removing biofilm, especially when used warm/hot.

Starsan should run around $20-25 for 32oz.
No need to make 5 gallons each time. I've found 2-3 gallons in a "half bucket" plenty. The working solution can be stored in a (small) bucket for dunking, soaking, and mopping, and a spray bottle for spot sanitizing. I mop Starsan on smooth surfaces, such as the inside walls of fermentation buckets, the rim, lids etc. The foam sanitizes as well as the liquid. Starsan is truly no-rinse. Wonderful product!

 

[Barakn]

How about using Starsan? That is a dedicated sanitizer. As long as the surface remains wet with it, it remains sanitized.

Not true. Look closely at the fine print on your Star San bottle. It says "For all applications, allow to air dry (but surface must remain wet for one minute)." Consider that the concentrate is 50% phosphoric acid but the working solution is diluted 1:640, reducing the concentration to 0.3%. This is fairly weak - I regularly overspray on my skin without concern (except I do wear eye protection). The sanitation relies on the outer surfaces of most cells having hydrophilic components, with the surfactant reacting with hydrophobic components to make them hydrophilic as well. This makes the organism the focus of a water droplet that gets smaller and smaller as the surface dries, concentrating the phosphoric acid and the surfactant until they become strong enough to actually kill. If Star San has worked for you, it's probably because you are doing a good job of cleaning beforehand, you've accidentally let Star San'd items dry without realizing that this was the important step, you are not diluting the Star San as much as the directions suggest, and/or you are properly pitching, aerating, etc. to give the yeast a good head start.

 

[Barakn]

Note that a Star San solution does kill many of the weaker organisms. The extra drying step might only be necessary for the hardier ones: spores, endospores, cysts, etc..