Was reading a brewing science textbook by Charles Bamforth yesterday and came across this on the subject of DMS: "SMM is heat -sensitive and is broken down rapidly whenever the temperature gets above 80 degrees C during the process.... If the boil is vigorous, most of the SMM is converted to DMS and driven off (The half life of SMM at 100 degrees C is 38 minutes, and this value doubles for every 6 degree C decrease in temperature)." In Denver, where I brew at 6,000 feet, the boiling point is 200 degrees F, or about 93.3 degrees C, meaning the half-life of SMM in my boils is 72 minutes - I reduce the SMM in malts by half in just over an hour. The flavor threshold of DMS is 30 parts per billion. So my friends, this is about the best argument I can find for keeping my 90-minute boils when using Pilsner malt. I'll also keep 60 for those using pale ale and standard two-row malts. The same book mentions other means of controlling DMS but they seem to be beyond the homebrewer in terms of technology and measurement required.