DMS as it’s termed has a cooked vegetable, sometimes over-boiled egg, taste. The term “smell of the ocean” encapsulates the idea too as seawater often has a high concentration of DMS due to its organic matter. This entry from the Oxford Companion To Beer, by brewing scientist Charles Bamforth, explains well the nature and causes of DMS in brewing.
Ales and porters are largely exempt from it. This is largely because ale malts are kilned at higher temperatures than lager malts. This neutralizes the precursor in the barley corn which creates DMS when wort is boiled. Also, ale and porter ferment at higher temperatures than lager, which tends further to inhibit DMS.
Thus, in much blonde lager, the precursor survives to the boil stage and is converted in the kettle to DMS. Some lifts off – becomes volatile and is lost to the atmosphere – in fermentation. The evolved carbon dioxide removes or flushes the compound out; however, closed fermentation systems can obviously inhibit this. Long aging of bottom-fermentation beer – lagering – used to remove the DMS as well, but less so today due to much shorter aging times and ubiquity again of enclosed tanks.
I believe the modern preoccupation to restrict as far as possible access of processed beer to oxygen, generally salutary to prevent premature oxidation, has this other effect.
DMS, in my experience, is a characteristic of most European lagers, and many craft lagers, but not all. Yeast differences play a role as well but it should be noted all lager yeasts in use around the world derive from two major strains, or so a reputed brewer once told me. This explains that the yeasts such as they are, relatively uniform, don’t impact the issue nearly as much as low temperature kilning and the other factors mentioned earlier.
Think, too, brussel sprouts and cabbage, the boiling … barley is a grain, not vegetable, but the distinction is a technical one from many viewpoints.
The Czech Pilsner Urquell, at least in the forms we get it, never shows the characteristic IMO. Some beers always show it, while for some it’s more off and on, which probably reflects irreducible processing factors caused by seasonal changes in barleys, temperature fluctuations, inconsistency of demand and thus varying storage times, and other factors.
The whole question too, is, “how much?”. In low concentrations, DMS is regarded by many brewers as part of the lager profile. Indeed some view it with favour and feel it contributes a “fresh” note to beer. At first I couldn’t understand this, but think of the seawater analogy…
I tried an experiment recently which was as striking in its simplicity as its results. I took a couple of beers in which I felt I could detect low DMS, one was Anchor Steam Beer, the other Creemore Lager. I left the can or bottle open on the kitchen counter for a couple of days, half-full. When I tried these again, the DMS taste seemed absent, especially in the Steam Beer. I believe escaping carbon dioxide carried off or expelled the DMS. It may be that lagers with higher concentrations of DMS, especially some German ones, wouldn’t react in the same way, or not quickly enough, since the beer would become sour or otherwise undrinkable for other reasons. Still, I thought the experiment noteworthy as a kind of speeded-up lagering.
DMS is detectable by some at the remarkably low concentration of 30 parts per billion. In my view, it’s just too idiosyncratic a taste to gain a mass market in North America, even allowing that the taste of drinks and foods should not be ironed into a characterless uniformity. Although most mass market brands today are rather bland, I remember the U.S. Budweiser, say, when it had a good flavour, 30-40 years ago. It never tasted of DMS, in contrast that was a “European” taste. It was the same for Coors and most of their competitors. True too of Labatt Blue in Canada. As all these beers are very clean today, the absence of DMS is even more apparent.
I’ll have to try Molson Canadian again – in that case I always thought the profile featured a hint of DMS. Perhaps it is the exception, in terms of mass acceptance I mean.
There are plenty of flavour elements to lager, the malt, hops, the yeast, to showcase to the exclusion of DMS or indeed other sulfur compounds that can appear in lager (for simplicity I am limiting discussion here to DMS). Pilsner Urquell, one of the great beers of the world and an odds-against survival of genuine 19th century brewing, shows the way. So do numerous other lagers including some craft beers. I never get DMS in Sam Adams Lager or in Blue Point Toasted Lager, for example. The absence of a sulfur hint doesn’t guarantee one will like the beer of course, but these two are good examples of reasonably widely available craft beers of quality in the general beer sense.
In France, Pelforth Blonde has a rich but exemplary clean taste in this sense, or it did, I haven’t had it lately. (Is the Blonde an ale though? Maybe that explains it). Stella Artois too although one always hopes for more character from the malt and hops. But note the success Stella has had in Canada, it’s not just promotion and marketing, it’s the beer itself.
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