Cork molds

[scruff_farrier]

So this was a little shocking for me last night. We had some family over so I grab a few bottles from the basement. It's usually a crap shoot if we put the heat shrink wrappers on them or not. This particular bottle we did, it's about a year in the bottle, also the only bottle I've had do this. When I took the bottle off there was mold on top of the cork, between the cork and the wrapper. I always sanitize my corks before I bottle. I just kinda confused how that could happen. But I'm more interested in why this happened so I prevent it from happening again.

 

[sour_grapes]

How do you sanitize your corks, and how do you apply the heat to shrink the capsules?

Depending on how you do it, I could imagine either of those steps leaving water under the capsule.

 

[scruff_farrier]

How do you sanitize your corks, and how do you apply the heat to shrink the capsules?

Depending on how you do it, I could imagine either of those steps leaving water under the capsule.

So we always float the corks in a big bowl of sanitizer while we are racking to a bottling bucket or clean carboy and make sure we stir them and let them sit for usually awhile.

Because we are sanitizing bottles while or after we rack. We always use starsan, and we don't have a pump yet, so minimum time the corks float for 20 minutes, clear threw when we pull the last one to bottle. Then we typically leave the bottles sit upright on the counter for a few days, with no wrapper.

I've had some corks pop when I used to try and rush threw everything so I can be a tad over cautious. Then a few days later we will get a pot of boiling water going and dip the wraps on the bottles in the boiling water.

Could there maybe have been some wine leakage around the cork? It varies a ton on wether we keep them on there side or upright in cases, just depends one the storage we currently have. I know for certain this batch was both originally on its side on a rack, and then we moved to a new place and I put them in cases and they have been sitting in case for a while now.

 

[cmason1957]

Soaking corks like that does little for you, except leave you open to the possibility of water logging the corks and mold developing later. It isn't recommended by most cork manufacturers. A short dunk is one thing, but a long soak can be problematic.

 

[Rice_Guy]

Mold will require an aerobic, high humidity environment with spores and a food source. You had all needed conditions.

. I just kinda confused how that could happen. But I'm more interested in why this happened so I prevent it from happening again.

? Leakage? If it was obviously wet this is a good possibility. ,, however having a little moisture which is trapped is enough to create high humidity. Next thing to ask is where were the mold spores came from? ,, it could be ambient air, example whole wheat bread has high mold incidence on the surface in summer, spores could have been on the cork. Food source? Cellulose in the cork works and a very very small seepage could also provide nutrition.

 

[scruff_farrier]

Soaking corks like that does little for you, except leave you open to the possibility of water logging the corks and mold developing later. It isn't recommended by most cork manufacturers. A short dunk is one thing, but a long soak can be problematic.

I did not know this. From now on we will just dunk them and then cork the bottles. I must of read or saw this somewhere to soak them. I think I read about boiling them also, but wasn't sure of that. Thanks.

 

[scruff_farrier]

Mold will require an aerobic, high humidity environment with spores and a food source. You had all needed conditions.

? Leakage? If it was obviously wet this is a good possibility. ,, however having a little moisture which is trapped is enough to create high humidity. Next thing to ask is where were the mold spores came from? ,, it could be ambient air, example whole wheat bread has high mold incidence on the surface in summer, spores could have been on the cork. Food source? Cellulose in the cork works and a very very small seepage could also provide nutrition.

Interesting, I never assumed it was possible. It was just strange cause it was the first one we ever had that happened to. Anything we could try to do different to not have it happen again?

 

[sour_grapes]

I would avoid boiling the capsules to seal them! I could easily imagine getting water in the capsule, then sealing it well, and trapping the water there.

 

[Old Corker]

I'm in the construction industry and we spend a considerable amount of time, energy and money on black mold avoidance. @Rice_Guy has the right recipe. Moisture, food, minimum temperature (65 degrees) and the spores. As for the question about where the spores come from, the saying goes "that **** is everywhere".

For my corks I use a corkadore (I've only ever seen that word except on this forum). A bucket with a plastic colander in it. Enough sanitizing liquid to cover the bottom and put to corks in the colander with a lid. The vapors from the liquid do the sanitizing and the corks never touch the liquid.

 

[sour_grapes]

For my corks I use a corkadore (I've only ever seen that word except on this forum). A bucket with a plastic colander in it. Enough sanitizing liquid to cover the bottom and put to corks in the colander with a lid. The vapors from the liquid do the sanitizing and the corks never touch the liquid. (emphasis added)

In particular, the sanitizer should be a sulfite solution (best with acid). That gives off germicidal vapors. StarSan, OTOH, is a contact killer.

 

[Rice_Guy]

Interesting, I never assumed it was possible. It was just strange cause it was the first one we ever had that happened to. Anything we could try to do different to not have it happen again?

NOTE: one if the requirements is humidity, I would first tackle humidity by not putting a capsule on till the cork is dry, I have never had mold on bottles but then I use Nomacork so food source and humidity retention are avoided. HUMM,,. I have been soaking left over Nomacork in meta solution (the lazy way to clean), twice in five years I have seen some mold in that bucket, likely because the meta was several months old and weak.

 

[scruff_farrier]

Ok, sounds good. I will try and implement these things. Ok, and the next more suspect question. Dump the wine? Or clean the cork off with some sort of cheap drinkable alcohol? I have ever clear around for almost this exact reason. I was inspecting it a little more last night and it almost seems like the mold was old and crusty.

 

[winemaker81]

Mold on the outside of the cork was a typical thing for me, as my storage conditions are not ideal. It's not dangerous, just unsightly, and (IMO) embarrassing if I give a bottle away.

Like @Rice_Guy, I switched to Nomacorcs and the problem went away.

 

[scruff_farrier]

I gotcha, ok. I might look into those for batches I'm planning to bottle age long term.

 

[Rice_Guy]

Mold on the outside of the cork was a typical thing for me, as my storage conditions are not ideal. It's not dangerous,.

the wine inside is a preservative,,, low pH, alcohol, and no oxygen. Basically food poisoning does not happen in wine

 

[scruff_farrier]

I geuss I was more worried about the cross contamination potential. Not that the wine itself was bad.

 

[Rice_Guy]

Mold will have created spores already, dumping will not change that. Like @Old Corker said the Spores are everywhere (seed).
Cell cultures tend to grow in waves which means that a population which is adapted for one set of conditions followed by another family which can metabolize what is left, followed by another family

I geuss I was more worried about the cross contamination potential. Not that the wine itself was bad.

 

[winemaker81]

the wine inside is a preservative,,, low pH, alcohol, and no oxygen. Basically food poisoning does not happen in wine

Your point is a good one that many folks do not realize. However, I was pointing out that the mold on the outside of the bottle is not a real problem, just unsightly, in case anyone thought they should toss the bottle.