Source of rubber smell?

While perusing the forums this weekend I came across a post where someone mentioned they had a rubbery smell in their wine. Nothing unbearable, but definitely present when your nose dives into the glass. I have had this same issue with pretty much all my kit wines, so I started digging into the forums to see if I could ferret out a cause. Unfortunately the opinions on the matter run the gamut. I’ve seen the following:

- High fermentation temp causing the yeast to create fusel alcohols
- Autolysis
- Chlorine in water

Before reading this I had attributed the smell to my rubber stopper, but I really don’t think that’s the problem. I ferment in my house, which is typically held at 76°F. My fermentation temperatures rise into the 80°F – 83°F range, which according to Sheridan Warrick’s book “The Way to Make Wine” is within the range that red wine should be fermented. If I’m correct, autolysis can be cause by high fermentation temperatures.

I also use Houston’s finest tap water, which I’m sure has chlorine. Per the instructions with the kits, I rinse out the juice bag and pour this into the primary. I've read that if you don't mind your tap water, then you won't mind it being in your wine.

I write all this to inquire again with the group, does anyone have any different opinions on what the source of this smell is? In the absence of a single, cohesive answer I’ll put on my chemist hat and start with the easiest variable to eliminate: chlorine in the tap water. Next batch I’ll use some type of bottled that doesn’t have chlorine. If that doesn’t cure the problem, I’ve been wanting to build a fermentation chiller/chamber for a while now, so I’ll go for that.

You folks have proven to have a plethora of knowledge, so I know someone here can shed some light on this. Looking forward to the discussion!

The correct fermentation temperature varies depending on which yeast strain you use

Goofynewfie said:

The correct fermentation temperature varies depending on which yeast strain you use

Click to expand...

You're absolutely correct. I guess one of the things I was hoping someone could chime in on is if going outside the yeast's acceptable temperature range would result in a rubber like smell.

Chlor
I'm not specifically familiar with the chlorine in water issue leading to rubbery odors. Chlorine (and chloramine) are the chlor chemicals in municipal water supplies. That chlor is the actor in "cork taint" - however that's more moldy or "wet dog" than rubber tho.

Temps
Higher than desirable ferment temps can lead to Hydrogen Sulfide (H2S) - particularly in certain yeast strains ... which, particularly in reductive conditions (lack of O2 ... i.e. in storage) can cause mercaptan formation. This can lead to that rubber fault.
btw: H2S is that rotten egg thing (aka "rhino farts").
Are you noticing rubber after a period of sealed storage?

In general to avoid H2S, use a yeast not prone to it ... ferment in the recommended temp range ... add appropriate nutrient doses as needed by that strain of yeast.
In the event you notice even the tiniest, slightest rotten egg smell post fermentation ... you could try treating for H2S prior to bottling just for good measure by carefully adding some extra K-meta (relative to pH) and then doing some splash racking prior to bottling - H2S is pretty volatile and so fairly easy to dissipate particularly if the problem is not already pronounced.
Other methods of dealing with H2S here ...
https://www.homebrewtalk.com/f25/do-i-have-stabilize-fine-278270/index2.html#post3457241
btw the above may help to dissipate some of that rubber smell as well.

Autolysis
... yep, that too. Again, causes mercaptans to form. Racking off the lees promptly at the end of active fermentation can help.
(Side note - The lees bed that a must is intentionally left on is typically obtained by doing a racking while the must is still cloudy with suspended yeast and then allowing *that* cloud of yeast to settle for the must to sit on.)

All this having been said, and particularly with my mentioning splash racking with the pre-addition of more sulfites ... the indiscriminate use of too much sulfites can leave a rubbery sort-of odor as well. Not common and this is not likely the problem as you'd have to have a pretty fair amount of it in there but just wanted to give that disclaimer.
Now ... as you may have noticed if you’ve ever looked into the technicalities of the subject ... measuring and dosing the appropriate amount of metabisulfite products to provide adequate "free-sulfite" in solution is pretty much like alchemy ... but if you are paying attention to your pH levels, minimizing inappropriate oxygenation of the must, and doing your best job at adding the “accurate” amount of sulfites to protect your wine ... you should not be getting off notes from over-addition of sulfites. Like I say, this is almost certainly not the problem.

I would suspect the H2S/mercaptan formation issue.
Treat it with the proper fermentation techniques and then be fastidious about not bottling anything with that H2S smell.
And as mentioned, your existing bottles/batches can also be helped to some degree by the copper techniques at the link above.

Jacob_Marley said:

Chlor
I'm not specifically familiar with the chlorine in water issue leading to rubbery odors. Chlorine (and chloramine) are the chlor chemicals in municipal water supplies. That chlor is the actor in "cork taint" - however that's more moldy or "wet dog" than rubber tho.

Temps
Higher than desirable ferment temps can lead to Hydrogen Sulfide (H2S) - particularly in certain yeast strains ... which, particularly in reductive conditions (lack of O2 ... i.e. in storage) can cause mercaptan formation. This can lead to that rubber fault.
btw: H2S is that rotten egg thing (aka "rhino farts").
Are you noticing rubber after a period of sealed storage?

In general to avoid H2S, use a yeast not prone to it ... ferment in the recommended temp range ... add appropriate nutrient doses as needed by that strain of yeast.
In the event you notice even the tiniest, slightest rotten egg smell post fermentation ... you could try treating for H2S prior to bottling just for good measure by carefully adding some extra K-meta (relative to pH) and then doing some splash racking prior to bottling - H2S is pretty volatile and so fairly easy to dissipate particularly if the problem is not already pronounced.
Other methods of dealing with H2S here ...
https://www.homebrewtalk.com/f25/do-i-have-stabilize-fine-278270/index2.html#post3457241
btw the above may help to dissipate some of that rubber smell as well.

Autolysis
... yep, that too. Again, causes mercaptans to form. Racking off the lees promptly at the end of active fermentation can help.
(Side note - The lees bed that a must is intentionally left on is typically obtained by doing a racking while the must is still cloudy with suspended yeast and then allowing *that* cloud of yeast to settle for the must to sit on.)

All this having been said, and particularly with my mentioning splash racking with the pre-addition of more sulfites ... the indiscriminate use of too much sulfites can leave a rubbery sort-of odor as well. Not common and this is not likely the problem as you'd have to have a pretty fair amount of it in there but just wanted to give that disclaimer.
Now ... as you may have noticed if you’ve ever looked into the technicalities of the subject ... measuring and dosing the appropriate amount of metabisulfite products to provide adequate "free-sulfite" in solution is pretty much like alchemy ... but if you are paying attention to your pH levels, minimizing inappropriate oxygenation of the must, and doing your best job at adding the “accurate” amount of sulfites to protect your wine ... you should not be getting off notes from over-addition of sulfites. Like I say, this is almost certainly not the problem.

I would suspect the H2S/mercaptan formation issue.
Treat it with the proper fermentation techniques and then be fastidious about not bottling anything with that H2S smell.
And as mentioned, your existing bottles/batches can also be helped to some degree by the copper techniques at the link above.

Click to expand...

Thanks for the input!

I haven't gotten any rhino fart smells, thankfully. Just for clarification, do the mercaptans smell more like rubber? I'm familiar with the smell of H2S as I'm an engineer in the refining/midstream world. And I often deal with systems to remove both H2S and mercaptans from hydrocarbons. But I've never smelled mercaptans as far as I know.

Typically the smell comes on after its been in secondary for a few weeks to a couple of months. Haven't paid close attention to the exact timeline, but I will on this batch I started Saturday.

I do a good job racking off the lees after active fermentation, so it doesn't sound like autolysis is the issue. And I agree with the alchemy behind sulfite additions.

Yep, some smell like rubber. But it’s complex stuff. Mercaptans and other contributing sulfide and disulfide chemistry both contributes to the varietal character of various grapes and wine styles ... and also wine faults. They contribute to a broad range of aromas/odors. There’s the good, the bad and the ugly.

If, as you said, they are coming on while they are stored in the secondary, these should generally be the ones which are more volatile and should be good candidates for getting rid of as noted above. Further, treating promptly is important as you can “head some of the trouble off at the pass” by doing so.

Ah, such good info on the mercaptans. I'll have to talk with some of our equipment vendors as well to see what their experience is with mercaptan odors. One of the processes we deal with regularly even produces a disulfide oil (DSO) stream we typically blend off in something like a natural gasoline stream.

As an update, started a Malbec/Shiraz blend kit on Saturday. Getting an egg smell now and temp is 82F.

What yeast did they supply?
82* definitely sounds high. Higher ferment temps are more useful for high-brix musts where you are using a higher speed yeast to chew through the sugar.
If they supplied a "range" of acceptable temperatures, that would not mean the whole range is desirable. I would immediately move the must to 72* to 75* (max).
If by chance they gave you RC212 as the yeast (just guessing) ... that yeast must be fed. If this is the case they should have provided you with yeast nutrient.

Any accumulated H2S will need to be dissipated ... however, as long as you insure the yeast, going forward, has the appropriate temp and nutrients, that aeration very well may occur on its own when you transfer from the primary to the secondary fermentor. The nose will tell.

Man, you're good. RC212 came with the kit. But, they didn't provide any nutrient, though I have some laying around I could throw in there. Should I do that, or is it too late to have any impact?

As an FYI, the upper temp range for RC212 per the Lalvin website is 30°C, or 86°F. Temp was still at 82°F this morning. I'll see if I can rig up some type of swamp cooler this afternoon when I get home. Not sure how much cooling I'll get given my locale.

If the only thing incommon between all your kits is your rubber stopper then its probably your rubber stopper. You could try a universal bung, they dont smell at all. Of its not that then maybe you got some bad water? WVMJ

I ended up making some version of a swamp cooler in my tub. Unfortunately Houston tap water is 80+ degrees. Fortunately I had a cooler if cold water left over from this past weekend.

Put some water in the tub, dropped in my bucket of wine and added some yeast nutrient to it, wrapped it in a wet towel, turned the fan on. I'll check it again in a couple hours. Oh and I bumped the AC down to 70. We'll see what kind of damage that does to the electric bill!

WVMJ said:

If the only thing incommon between all your kits is your rubber stopper then its probably your rubber stopper. You could try a universal bung, they dont smell at all. Of its not that then maybe you got some bad water? WVMJ

Click to expand...

Bought one of those universal bungs last time I was at the store, never tried it though. I'll use it this time and see if it makes a difference.

Got the primary fermentor temp down to 75F tonight. Hopefully I mitigated any future problems.

TexasWine said:

... they didn't provide any nutrient, though I have some laying around I could throw in there. Should I do that, or is it too late to have any impact? ...

Click to expand...

Nutrients may still help a bit. You're likely pretty far into the ferment and in most (but not all) cases you want to get your nutrient additions done by about the 1/3rd point (when your ferment sugar-use is about 1/3rd done) ... but it may help some.

Some lengthy blibber about nutrient additions ...
https://www.homebrewtalk.com/f32/how-often-should-you-add-yeast-nutrient-353615/#post4404411
... just in case you need some toilet reading-material or are insomniac ;-)

WVMJ said:

If the only thing incommon between all your kits is your rubber stopper then its probably your rubber stopper. You could try a universal bung, they dont smell at all. Of its not that then maybe you got some bad water? WVMJ

Click to expand...

I went from primary to secondary yesterday. Tried to use the universal bung but I wasn't confident in the seal it made with the carboy. It was very loose fitting. So I ended up going back with the rubber one.

Have you ever had this issue with the universal bung?

Jacob_Marley said:

Nutrients may still help a bit. You're likely pretty far into the ferment and in most (but not all) cases you want to get your nutrient additions done by about the 1/3rd point (when your ferment sugar-use is about 1/3rd done) ... but it may help some.

Some lengthy blibber about nutrient additions ...
https://www.homebrewtalk.com/f32/how-often-should-you-add-yeast-nutrient-353615/#post4404411
... just in case you need some toilet reading-material or are insomniac ;-)

Click to expand...

Thanks for the link! I learned a lot. Hopefully I don't end up with any kind of weird taste because of how late I added the nutrients.

Since you gave me a heads up on the fermentation temp I've been able to keep it between 67-69F using a bath tub, towel and a fan fashioned into a swamp cooler. I was surprised that I can keep the wine between 6 and 8 degrees below the setting on my AC. I think I'll start doing all my wines this way, at least in the summer months.

As far as finding the source if the rubber smell, I don't think this batch will be a good test subject since I've already let the fermentation temp get high. Also, the universal bung was a no go. I'm not confident in the seal it makes with the carboy. And I've used Houston's finest water in this batch.

Really the only thing I've done differently with this batch is bring the temp down later in fermentation. Burr I guess we'll see if that makes a difference!

I'll keep this thread updated should I have any more discoveries.