DMS

[bubba]

I was looking at this:

http://en.wikipedia.org/wiki/Dimethyl_sulfide

Since this indicates the boiling point of DMS is 37 degrees celcius, couldn't you hold the wort at that temp for a little while to boil off any residual DMS. I have yet to use any pilsner malts and was concerned becasue my chill isn't as quick as Jamil's. Perhaps a really slow chill could be beneficial if you couldn't do it in a couple minutes and had good sanitation. Does anyone have any knowledge or experience on this?

[BeerMan]

I read the link they state 37C about 99F is the boiling point of DMS I’m not a scientist so I will go out on a limb and make some assumptions and ask some questions.

Have you had DMS problems with past batches, do you boil covered or uncovered.

How accurate is the Wikipedia data.

The 37C BP is for just DMS not DMS mixed with other compounds i.e. wort does this alter the BP temperature ?

With a 37C BP how much DMS is left to drive off.

In the end I would use what I know works if I had a DMS concern I would boil uncovered and would increase my boil time if required. Cool as fast as you can get a good cold break, get into pitching temps and put that yeast to work. How do you cool if it is not very fast that might be the process you might want to tweak.
Happy brewing
Mike

[jamilz]

I believe that only occurs at the wort surface, so holding at 37C won't help unless you can exchange the wort across the surface, for example when boiling.

[Kaiser]

Theoretically, you can bubble CO2 or even air through the wort at a temp above 37 to drive of excess DMS, but I'm not sure that this is at all practial for the home brewer.

You mentinoned that you haven't had any DMS problems yet, but you may want to start using pilsner malt. I suggest that you do a 90 min boil and try to chill as fast as your system allows you and see if you get any noticable DMS in your beer. If not, you are fine. If you do, you may want to look into a different chilling techique.

Commercial German breweries have their wort sit for a long time at higher temps (whirlpool rest). For many of them the 90 min boil is sufficient to lower the DMS and DMS potential (SMM) such that the DMS in the final beer is below the sensory threshold. If the kettle boil is shoter additional measures need to be taken to drive off DMS after the whirlpool.

Kai

[bubba]

Thanks for everyone's input. I have been using an immersion chiller. It takes a bit over a half hour to chill down to around 70 degrees. The time and temp fluctuate depending on the time of year. I guess I will just continue and give a malt bill with Pilsner malt a try. My initial curiosity came about from recently reading that Charlie P doesn’t use a chiller (in BYO) but just places his kettle in an ice bath with good results. Thanks again for everyone’s response.

[DannyW]

Pope says 140F is the magic number for DMS production, so it's how fast you can get there, rather than how fast you can get all the way to 70F.