Of Sulphides in Beer and Gastronomy…

Hydrogen-sulfide-2D

Brookston Beer Bulletin has just published a very interesting technical paper from 1970 which describes the problem well of excess hydrogen sulphide in beer. Other sulphides, especially “DMS” (dimethyl sulphide) can add similar objectionable tastes to beer.

The tastes in question are often described as an over-boiled vegetable taste, or a barnyard or sulfur smell and taste – most have tasted water from a country well which has this taste: not very pleasant. The spa waters of some areas offered the same kind of aroma but in time became regarded as healthful, perhaps by analogy to the usefulness of night soil in agriculture or indeed the popular idea that a medicine which tastes bad can be good for you.

The paper is by two scientists who describe a method to eliminate the taste from beer, it involved an electrolytic process to add copper to precipitate out the compounds in question. The applicants obtained a patent, but I don’t know if their process was ever or still is used in commercial brewing.

The problem, especially for pale lager beer, is still very much with us based on many years’ tasting of both mass-production and craft beers. On a trip to Munich and area a few years ago, a good many of the helles beers had the taste in high concentration, I could not finish some glasses due to this.

Some beers there, however, and some here, avoid the taste. Pilsner Urquell has never featured hydrogen sulphide or DMS in my experience. In the past, I found Heineken usually had it but recently the beer seems much cleaner and this is a great improvement, IMO. In a recent U.S. sample of PBR (Pabst Blue Ribbon), I thought the characteristic whiff quite evident. Many craft lagers have the taste, but certainly not all.

Some would argue the taste has become part of the profile of quality blonde lager. Over a swath of Europe on my last trip, I saw people happily drink beers with the taste, I think they just don’t “see” it – have become accustomed  – and some too may have low sensitivity. From a strictly gastronomic viewpoint though, no beer which offers the flavour can ever be a great drink, in my opinion to be sure. And the fact that scientists recognized the problem, not just in the 1970 paper mentioned, but in many other studies starting from the mid-1900’s, shows breweries have been concerned about it. Even before then, the flavour was noticed and objected to, some English brewers complained of a “garlic” flavour in the European lager starting to reach British shores at the end of the 1800’s.

The reason pale lagers are susceptible is, many pale malts used to brew lager contain a “precursor” which, after mashing and fermentation, produces the compounds in question. It may come from fertilizers used in agriculture. Other brewing materials can contain sulfur, hops too, but generally scientists have ascribed the cause to precursors in pale malting barley, especially varieties used in Continental Europe. Interestingly, some English ales have a similar taste. Many pale ales from Burton-on-Trent, or the Trent Valley generally, had what was called the “Burton snatch”, and some English beer still features the taste. Whatever the specific cause in that case (some have pointed to brewing waters), generally, ales and porter – top-fermented beer, that is – avoid the taste.

Also, the darker the malt, the fewer the precursors because the higher temperature in kilning the moist barley malt inhibits their formation. Brewers have also told me that the caramelized flavours of a darker beer can cover over the taste, whereas in a pale beer “there is nowhere to hide”.

It is hinted at but not expressly stated in the 1970 paper why the problem needed attention. The authors state that in aging or conditioning of beer, the secondary slow fermentation produces further CO2 which carries away the smelly sulfides. This is surely one reason why lager was traditionally cellared for many months before sale. True, the containers were enclosed but one can imagine that porous wood allowed the vapours in the vats or barrels to percolate out. Anyway, the containers once opened would have flushed out their surface vapours to the air. But from later in the 1800’s, traditional cellaring times became shorter and shorter to ensure availability of beer in the market and not lock away capital for too long. The adoption of mechanical refrigeration assisted doing away with long conditioning in naturally cold cellars or caves. The general adoption of closed fermentation systems, later in the 1900’s, compounded the problem, for reasons that will be obvious.

Hence in my view, how the “garlic” problem arose. In the 1970’s, brewers spoke of “7/7” beer: brewed in seven days, aged in seven, then out the door. I can’t speak to aging practice today either in big or small shops but from what I’ve heard, extended aging is not typical for most pale lager. Homebrewers however are familiar with the sulfide issue and some ensure a proper aging time to “clean up” green flavours such as hydrogen sulphide.

A fine lager should feature prominently the flavour of fine malt and hops. Yeast contribution if benign is certainly to the good, yeast always contributes palate-character to beer. But the sulfides mentioned do nothing for it, IMO.

 

Note re image used: the image shown is in the public domain, and was sourced here: https://commons.wikimedia.org/wiki/File:Hydrogen-sulfide-2D.png