Returning somewhat to the original question about the benefits of a 90-minute boil, are there benefits to a longer boil?
I've recently done a series of beers with primarily pilsner malts, and the first two still came out with some DMS, despite a good rolling boil and pretty rapid cooling with immersion chiller. As I pondered this with a few people from my homebrew club, one or two of them suggested they typically boil even longer than 90 minutes, close to 2 hours, for pils-malt beers. Note that we are at 5,000 ft, and wort boils at 203, not 212 F. At least one person's perspective was that at this lower temp, it takes longer to drive off the DMS precursors.
Also, this wiki http://www.homebrewtalk.com/wiki/index.php/Dimethyl_sulphide
a 100-minute boil is suggested for DMS elimination. I assume this is for sea level.
I can report that my first to pils-malt beers, boiled for 90 minutes, have some DMS, but my third beer, boiled for 105 minutes does not.
Does anyone have any thoughts about this? Is 90 minutes enough, particularly at higher elevations?