diacetyl, sour beers, and boil times

[Bad Goat Brewing]

In the past I've boiled the wort for my sour beers for 90 minutes because i use a fair amount of german pilsner. But I've been thinking, since brett will eat diacetyl, do I need to this? Do i even need to boil for an hour? Does anyone know how long Cascade Brewing or Russian river boils their wort for sour beers?

[brewinhard]

I think you are getting confused between diacetyl and DMS. A 90 minute boil is typically recommended when using a high percentage of pilsner malts because they are lightly kilned and can produce higher levels of residual DMS during the boil if not boiled vigorously or for a longer period of time. Diacetyl is a ketone produced by yeast during initial stages of growth and can be metabolized given time on the lees with warmer temperatures to speed things up (a few degrees warmer than ferment temps).

Brett will consume diacetyl produced during fermentation (including from pediococcus) given enough time (3-5 months or so).
Brett on the other hand, as far as i know, will not convert DMS like it does diacetyl. So continue to boil your sour beers for 90 minutes if they contain pilsner malt to help reduce the chances of DMS in the finished product (brett or not).

[Bad Goat Brewing]

I was under the impression, and probably mistakenly, that dms is pretty volatile at room temperatures and is not normaly a problem for beers stored in 60+ fermenter long term. Am I completely off base with this?

[Klickitat Jim]

I think the boil point of dms is above the temp its created at, so no, room temp isnt going to do it.

Edit: per wiki its 99º

[Ozwald]

I was under the impression, and probably mistakenly, that dms is pretty volatile at room temperatures and is not normaly a problem for beers stored in 60+ fermenter long term. Am I completely off base with this?

You can't age out DMS. You have to boil it out.

[Bad Goat Brewing]

Why doesn't Berliner Wiesses have a noticalbe DMS flavor? Or am I just missing that flavor in them?

[Klickitat Jim]

My guess is if any beer doesn't have DMS its because they either used a low smm malt or they did a proper boil.

[brewinhard]

Why doesn't Berliner Wiesses have a noticalbe DMS flavor? Or am I just missing that flavor in them?

When I do my berliner's I use a no boil approach. I do complete a 20 minute "'boil" decoction with the hops on about 1 gallon of the wort which I then add back to the mash tun to bring it up to mash-out temps before draining, chilling, and pitching the lacto. I have never noticed any DMS issues even when using a large portion of pilsner malt. I too am curious why DMS does not seem to show up in this style when it really should. Maybe not enough of the true pre-cursor to form DMS isn't produced not leading to noticeable DMS formation in the finished product? This has always been a mystery to me...