Sulphury yeast

[PatFiori]

Hi,

I'm brewing at a brewpub up in humid Ottawa. I'm having an issue with my ale yeast. It seems to be producing DMS in my lighter beers. I was under the impression that only certain strains of yeast produce DMS via DMSO and this occurs at lower fermentation temperatures. DMS production has only started to occur when it started to get hot. Here is the part that gets me, when I crash the yeast, the DMS flavour gets worse. It clears up somewhat during conditioning but not enough. This issue never arose during the cooler months. It probably occurs in my darker beers as well, but they are thicker and it is not as noticeable.

Can DMS be scrubbed out like SO2. I do have SO2 being produced but that is because our water supply has heated up so wort is coming of the heat exchanger at 83F. I normally ferment at 72F. I'm pretty sure I'm killing off yeast as I pitch. Unfortunately I inherited this yeast strain and the owners are in no hurry to change strains.

I have no idea what to do aside from using fresh yeast constantly.

Cheers
Patrick

[crassbrauer]

Before I blamed the yeast or some other microbes, I'd look into boiling long enough and well enough and keeping your whirlpool rest as short as possible before cooling. Since your water is warmer and therefore you can't cool as quickly, it probably has to do with your wort temperature.

Microbes can create DMS from DMSO but from the sound of it, I'd try to improve your brewhouse work first and see if that fixes the problem.

Good luck

[jason.koehler]

As crassbrauer stated, DMS is usually a boiling problem, and is usually more common in when using lager malts than ale malts. The general rule of thumb is that if you're making an ale with DMS, then you're doing something wrong on the hot side. Also, the faster you can chill your wort from knockout, the more you can exponentially decrease the amount of DMS production. It is also very difficult to lower DMS levels after it has reached flavor threshholds in the beer.

Fix has some good information on reducing DMS in Principles of Brewing Science, and I downloaded a scientific journal paper from this site on the reduction of DMS. I'll e-mail it to you if you'd like, just send me a PM with your address.

[bruboss]

local help

I think people are missing the point that the problem is seasonal. The seasonal nature of the problem would imply a seasonal change in something to create the problem. Being in Montrteal, not too far away, I would suspect a water problem. I boil all my mash water to try to give me a uniform start point. I know from my 10 years here that there is a definite seasonal nature to the water supply.

Your yeast may also be susceptible to DMS production and a new strain might help. I have a great ale yeast if you want to drop by and take some to try out.

Drop by some time and we could have a chat or give me the address and when I'm next in Ottawa I will come in.

Chris

[Sauce]

I believe crass and Jason hit it on the head.


And Crass did reference warm summer municipal water temps during knockout as a possible cause:

Since your water is warmer and therefore you can't cool as quickly, it probably has to do with your wort temperature.

I have the same problem in the summer with my single stage heat exchanger if I'm not quick and timely with my wirlpool and settling times.

Here's a good thread on DMS - production, reduction and tech info from last year.

http://www.probrewer.com/vbulletin/showthread.php?t=4390&page=1&pp=15&highlight=DMS

[PatFiori]

Thanks Sauce,

I found that thread extremely informative. I will play with my brewhouse a bit and see if I can't figure it out. I'm not completely convinced that something else may be contributing but first things first.

Patrick

[Moonlight]

Just to be sure, when you say DMS do you mean the canned corn flavor? Other sulfur compounds can be confused and have different causes...

[GarySped]

Replies about hotter summers and boiling and cooling times are likely right on here (unless you have some wort spoilers which would give a parsnip veggie odor). So follow good rolling boils (10% evaporation rates? - no drip-backs), maintain sanitation and get that wort through and off whirlpool and pitch as fast as you can.

George Fix might have put some good info out there but he is not your best expert on this.

Gary.
Brewing and Distilling Analytical Services.

[RaySherwood]

Have you tried slowing your transfer rate to see if you can get the temperature down to the 72* pitching rate you desire. A slower transfer might get that water too absorb more heat and cool it faster than an additional rest.

Or you could try brewing at night!

Good luck,
Ray