A longer boil can help eliminate DMS. The half-life for DMS is 40 minutes, so half of the DMS will be boiled off in a 40 minute vigorous boil. So if we do the math, a 60 minute boil gets rid of 64.7% of the DMS and a 90 minute boil rids us of 79% of the DMS. That is why most experienced brewers recommend a 90 minute or longer vigorous boil. Cooling your wort quickly after the boil helps keep more DMS from forming as well - which can't be boiled off obviously. Just tricks of the trade when using lighter, paler malts.