Worty Off-Flavours

Originally posted by Frank
I wish I could offer advice but I have none. I am curious though why you are boiling ninety minutes if not for greater hop utilization or for higher gravity, which I assume is not an issue at 1.032. Just like that taste you get from a longer boil?

You generally want to avoid perceptible levels of Dimethyl Sulfide (DMS), which is a sulfur compound produced during making of beer that most people experience as the aroma of cooked or creamed corn.


DMS is present to some degree in all beers. People can perceive DMS even at very low flavor thresholds but this ability (and the accompanying annoyance level) varies according to the individual. DMS is desirable at low levels in some beer styles but excessive levels of DMS will create a an off-flavor and aroma cooked corn.

All malt contains a chemical called S-Methyl Methionine (SMM) which is the DMS precursor. Very pale malts such as Pilsner tend to have somewhat higher SMM levels due to the very low temperatures used in kilning. This results in higher DMS production because heating the SMM present in pale malt will always produce some DMS.

To compensate for this when you’re using Pilsner Malt:
Boil the wort vigorously for 90 minutes or longer
Don’t cover your boil pot so the DMS can be dispersed
Rapidly cool your wort after the boil

Actually, you should always do the second two for a variety of reasons, and aging your beer also helps.

Originally posted by Frank
I wish I could offer advice but I have none. I am curious though why you are boiling ninety minutes if not for greater hop utilization or for higher gravity, which I assume is not an issue at 1.032. Just like that taste you get from a longer boil?

There are a number of benefits to a longer boil. DMS reduction is one, but it also improves stability, head retention and some other things.