FWH and DMS
Our kettle/boiler design is not great. Boiloff rate is typically 5% per hour *at best*. Consequently, I've had some issues with DMS in my beers.
I've mitigated the problem by doing 2 hour boils but still was getting some DMS nose. It seemed to vary in intensity.
Lately, I've been playing with first-wort-hopping in an effort to get the most IBU out of my precious, precious hops. This seems to have had the side-effect of eliminating my DMS woes. I've now begun to add nearly all my bittering hops as a first wort addition and my beers have never been better!
This despite the FWH also reducing my boiloff rate to 2.5%/hr. The boil is a lot different, too. Much smaller bubbles, dramatic reduction in anti-foam use.
Mostly, I'm just thrilled to have gotten my DMS problem in hand, but I'm wanting to know why this works. Do the smaller bubbles in the boil blow off DMS better? Or...?
I suspect they do. If you have more smaller bubbles, you have higher surface are for wort stripping. The is the basis of the design of the Briggs symphony external calandria as opposed to using wort spreaders which are used by virtually everyone else.
Have you changed your malt recently ? the levels of DMS precursor make a major difference to the boil / evaporation required
Makes sense on the surface area theory. Same malt brands, although I suppose the amount of DMSP varies with each lot, or at least year-to-year.