How Accepted Is The Reinheitsgebot With German Consumers?

This is part of my series to discuss 500 years of Reinheitsgebot.

This time, we’re discussing consumer acceptance, which is something, as reinheitsgebot.de claims, is very high among German consumers.

Question 7: How Accepted Is The Reinheitsgebot With German Consumers?

Their answer:

According to some study, 88 % of all people asked want beer to only be produced from water, malt, hops and yeast. 89 % of all Germans have heard of the Reinheitsgebot, in the East of Germany it is even better known than in West. 77 % of all people asked would like to see a purity law for other foodstuffs.

According to some other study, 79 % of all Germans think that German beer brewed according to the Reinheitsgebot requires special protection.

My answer:

Well, a recently published study paints a different picture: more than 60 % of the over-60 demographic said that the Reinheitsgebot is very important in their buying behaviour. On the other hand, only 25 % of the 30-and-under demographic agreed with that statement. Also, only primarily the older demographic would agree that German beer is superior to foreign beer because of the purity law. Generally, support for the purity law in Germany seems to be going down.

Another thing to point out when people ask for a purity law for other foodstuffs: it already exists. At least in the same form as it exists for beer. Germany has complex legislation that quite strictly regulates what you can and cannot put into certain food, including the requirement to declare everything that is put into the product.

If consumers want a purity law for other foodstuffs in the same restrictive manner as the 1516 Reinheitsgebot, that’s an entirely different matter, though. But then, which consumers would really like to see a limitation in bread ingredients to only e.g. water, wheat, salt and yeast? No other herbs or spices, no other grains, just an arbitrary list of ingredients. Doesn’t exactly sound appealing.

Which Additives Are Prohibited When Brewing According To The Reinheitsgebot?

This is part of my series to discuss 500 years of Reinheitsgebot.

Last time, I wrote about whether German brewers still brew according to the purity law. After a detailed discussion about what is actually allowed according to modern law and how reinheitsgebot.de is imprecise and conflates the historic purity law with the modern law that is actually in effect, I will answer a follow-up question to shed more light on what the “according to Reinheitsgebot” thing is actually about.

Question 3: which additives are prohibited when brewing according to the Reinheitsgebot?

We previously established that you’re allowed to use barley malt, hops, water and yeast for bottom-fermented beers, and for top-fermented beers, you can also use malt made from cereal other than barley, various brewing sugars, and food colouring made from sugar. And, what I didn’t mention last time, because it’s such an obscure niche, artificial sweeteners for some low-alcohol beers.

reinheitsgebot.de in their answer insists that it’s only malt, hops, water and yeast for beers according to the Reinheitsgebot, and say anything else is prohibited, while the EU allows a whole lot of other things to be put into beer. This list contains things from food colouring made from sugar, to lactic acid, to various artifical sweeteners and stabilizers.

Now, what they don’t mention is that the modern Vorläufiges Biergesetz does allow some of these ingredients. And for others, in particular lactic acid, there’s a way how German maltsters and brewers “cheat” the system.

Lactic acid, among other things, is often used to treat the liquor (brewing water) to change the pH level. Lactic acid is naturally produced by lactic acid bacteria, and commercially available in food-grade quality. Now, as a German brewer, you can’t just add lactic acid, so there’s a type of malt, called Sauermalz, that German maltsters produce: the malt is inoculated with lactic acid bacteria, which then produce lactic acid. The malt spec tells you how much lactic acid it contains, and based on how much lactic acid you want to have in your mash, you adjust your grist to use more or less Sauermalz.

But there’s another aspect about the Reinheitsgebot that reinheitsgebot.de isn’t very clear about: there’s actually a restriction on what beers you can call “brewed according to the Reinheitsgebot (of 1516)”. And it’s not all beers that adhere to the Vorläufiges Biergesetz. No, the use of that phrase is controlled by a different decree with the wonderful name “Zusatzstoff-Zulassungsverordnung“. It regulates what kind of additional things you’re allowed to put into all kinds of food and drinks, including maximum quantities. It also regulates the use of the phrase “nach dem
deutschen Reinheitsgebot gebraut” and says that beer sold under that label can’t contain certain ingredients that are actually allowed according to the Vorläufiges Biergesetz. In particular, it excludes food colouring, sugars, and any other gas than nitrogen and CO2 that has been produced through beer fermentation.

And that’s the mess of how this more strict Reinheitsgebot that vaguely resembles that law from 1516 is implemented within the legal framework that is the Vorläufiges Biergesetz of 1993. It’s a patchwork, it’s confusing to customers that try to understand the legal basis and limits for beer producers, and in the end only comes down to a marketing phrase that brewers can use on their beer labels and their advertising if they restrict themselves even further beyond the limits that are imposed by the law.

But at least we got to bottom of what the marketing phrase “Reinheitsgebot” really means and how it’s implemented legally.

Do German Brewers Still Brew According To The Reinheitsgebot Of 1516?

This is part of my series to discuss 500 years of Reinheitsgebot.

The website reinheitsgebot.de has an FAQ with questions and answers that are supposed to explain the purity law. This is my first article of a series of “Frequently Questioned Answers” where I will discuss these explanations. Unfortunately, I can’t directly link to the individual questions and answers, but bear with me. I will summarize the website’s answer, and add my own comments.

Question 1: do German Brewers still brew according to the Reinheitsgebot of 1516?

Their answer: according to reinheitsgebot.de, the purity law of 1516 forms the basis for the current law, the Vorläufiges Biergesetz of 1993, and because of that, beer is still a natural product like 500 years ago. But the production has changed and has been modernized, where all steps and the natural ingredients are closely monitored. But even nowadays, German breweries aren’t allowed to use artificial aromas, artificial colouring, artificial stabilizers, enzymes, emulsifiers, or preserving agents. Beer is still made out of malt, hops, water and yeast, and is as natural as ever.

My answer: the claim that the purity law forms the basis for current legislation is indeed a bold one. As discussed in a previous article, the original purity law allowed barley, hops and water, with a most likely implied use of yeast or spontaneous fermentation. When you compare this with the Vorläufiges Biergesetz, § 9 (1), this seems indeed true: it says only barley malt, hops, water and yeast may be used for bottom-fermented beer.

Wait a second… barley malt? Bottom-fermented beer? There is a difference after all! Yes, compared the historic predecessor, the German law is stricter for bottom-fermented beer. So lager beer uses a subset of the ingredients that were allowed back in 1516. On the other hand, though, it means that modern beer can’t necessarily be brewed with all the freedoms that the 1516 law gave: brewing beer with unmalted barley, which was allowed 500 years ago, is prohibited under current law. But only for bottom-fermented beers.

So what about top-fermented beers then? Just have a look at Vorläufiges Biergesetz, § 9 (2), which states that other ingredients are allowed as well, specifically malts made from other grains (such as wheat, rye, oats, spelt, buckwheat, …), “technically clean” cane sugar, beet sugar, invert sugar, starch sugar, and colouring made from these sugars. These are all ingredients that are allowed in the current law, but definitely fall outside the 1516 law. So, depending on the beer that you’re talking about, a top-fermented beer brewed according to the current law, may or may not conform to the 1516 law.

In summary, the modern law shows some similarities with the historic law, but even greater differences. Any beer style brewed with any other malt than barley malt, is perfectly legal in the current law, but falls well outside the historic purity law. The claim that German beers are brewed according to the 1516 purity law is definitely true for some of them, but is not reflected at all in either the current legislation or some of the popular German beer styles nowadays. And that’s just when we’re looking at the ingredients.

The Vorläufiges Biergesetz (§ 9 (6)) contains some more points in what other things may be used in the production of beer. It specifically allows anything as clearing agent for wort and beer that works mechanically or adsorbing, and that can be removed from the wort or beer again, with the exception of small amounts that are “technically unavoidable” and hygienically, olfactory and taste-wise harmless. So beer can be filtered, as long as the stuff that is used for filtering can be mostly filtered out, but don’t worry about it, because anything that is left behind in the beer won’t harm you, and you won’t taste or smell it.

Beer is filtered to remove haze and other matter that may have a negative impact on the shelf-life of the beer itself. That process is usually called stabilization. As long as the stabilizers that are used are natural, it’s still okay, right? Unfortunately, no. A very common and popular filter is PVPP  (polyvinylpolypyrrolidone), which is sold under brand names such as Polyclar, Divergan, or Crosspure by various manufacturers. PVPP is added as a powder to the beer, clarifies and stabilizes the beer, and leaves behind a slurry on the bottom of the bright tank. This is perfectly fine under current law, but it’s also something that at least I would consider an artifical stabilizer.

So, when carefully considering the current law, and comparing it to what reinheitsgebot.de says about German brewers still brewing according to the Reinheitsgebot, my conclusion is that German brewers can still brew according to the 1516 law, but the 1993 law gives brewers much more freedom in what is used. And, to my knowledge, German brewers do use these freedoms.

500 Years Reinheitsgebot? The Original Source

In order to be able to discuss about the Reinheitsgebot, we shall first establish what the law text originally says, in its original language, and what it means in modern language.

The 1516 Reinheitsgebot is rooted in the Bayerische Landesordnung of 1516, a law enacted in that year to harmonize the different local Bavarian laws in all kinds of different legal matters, be it policing, milling, building, trading, fishing, or brewing. This law contains one passage that regulates the allowed beer ingredients, and originally says (in Early New High German):

Wir wöllen auch sonderlichen / das füran allenthalben in unsern Stetten / Märckthen / unn auf dem Lannde / zu kainem Pier / merer stückh / dann allain Gersten / Hopfen / unn wasser / genommen unn gepraucht sölle werdn.

Translated to Modern Standard German it says:

Ganz besonders wollen wir, dass forthin allenthalben in unseren Städten, Märkten und auf dem Lande zu keinem Bier mehr Stücke als allein Gerste, Hopfen und Wasser verwendet und gebraucht werden sollen.

Translated to Modern English, this means:

Exceptionally so we want that henceforth, everywhere in our cities, market towns and on the countryside for no beer more pieces than alone barley, hops and water shall be used.

So, the language is very clear: no matter where in Bavaria you’re brewing, all you’re allowed to use is barley, hops and water. A common question here is: but what about yeast? Well, the nature of yeast was not fully understand until several hundred years later. This ingredient being left out is usually interpreted that the use of yeast is implied, that is if you’re not relying on spontaneous fermentation.

Another detail is also quite interesting: it specifically mentions barley, not malt in general or barley malt, but only barley. This is apparently based on the Munich purity law that had been enacted a few decades earlier, while other purity laws, such as the Landshut purity law, does mention malt, without a limitation to a specific grain. As I said before, the 1516 purity law was implemented as a harmonization, and thus overruled both the Munich and the Landshut purity law. Its emphasis on barley, and not malt, is quite a crucial detail here. I’ll discuss that in a later article.

500 Years Reinheitsgebot? Let’s Discuss

In 2016, the German Reinheitsgebot (beer purity law) is being celebrated to be 500 years old. According to some official document from 1516, beer is only meant to be brewed from barley, hops, and water, and has been the only brewed like that since then in Bavaria, and later in all of Germany. Or so they tell us.

Briefmarke 1983 Reinheitsgebot

I, for one, am highly suspicious about this. My research into historic brewing, both in Germany and Bavaria, have shown me otherwise, that these are neither supported by documented historic brewing practice nor by the legal situation of that time.

The Reinheitsgebot’s lobbyists proponents is mainly Deutscher Brauer-Bund e.V. who have prepared a website with lots of information for the anniversary, including a list of Frequently Asked Questions, to inform the public about this supposed 500 year old tradition that only wants the best for all of us beer drinkers. Having sifted through that material, I stumbled upon imprecise language, which is corrected and/or justified in other places. I suspect that the Reinheitsgebot proponents exactly know about all these imprecisions and inconsistencies, and yet resort to them because they serve a purpose.

I find this highly problematic. I therefore decided that I will present my view on these matters in a “Frequently Questioned Answers” format, where I will point out and correct imprecisions and inconsistencies, all based on facts and backed by sources. In addition that, I will explain why I think the Reinheitsgebot, the official narrative around its history, and its practical implementation in the form of the current German beer-related legislation is not only unhelpful to German beer culture, but how it has also helped erase the rich historic Bavarian and German traditions that have gone beyond just barley, hops and water.

With this series, I plan to further and enrich the discussion about the state of German beer and the planned 500 year celebrations, and help the discourse about the future of German beer.

19th Century Brewing Methods in Germany and Austria

Only the other day, I stumbled upon a book called “The Art of Brewing“, written by one David Booth, published in 1834. It has a whole section of brewing in foreign countries, discussing differences in brewing between Munich, Prague, Vienna, and other cities. The basis for this section is credited to two unnamed guys, can you guess who?

For the greater portion of ” the Brewing in Foreign Countries,” I am indebted to the manuscript and oral communications of two German Brewers (from Vienna and Munich), who have been, and now are, visiting the principal towns of Europe, for the laudable purpose of acquiring information concerning their business.

Yep, that sounds very much like Gregor Sedlmayr and Anton Dreher.

I also found another book, “Vollständige Braukunde” by Johann C. Leuchs,  that discusses the brewing methods of various German cities. In this article, I will try to summarize and discuss different German brewing techniques from the 19th century, and how they would be seen from a modern (home)brewer’s point of view.

Munich

For the mash, a mash tun made out of copper, with a false bottom, and a second, smaller copper, were used. The second copper was used for boiling the mash. The standard recipe is described to be 8 quarters of malt and 60 pounds of best Bavarian or Bohemian hops to produce 27 barrels of keeping beer. Calculating what the outcome of that would be, that would be a beer with about 6 to 7.5 % ABV, with probably 35 to 50 IBU. It does mention the Munich beer as keeping beer, meaning it was matured, or lagered, for a relatively long time.

The coarsely ground malt is doughed in, while the small copper is used to bring liquor to a boil. The boiling liquor is then added to the mash, to result in a 40 °C mash. Then a decoction is drawn, and brought to a boil. The author mentions a thick froth that is beaten down back into the mash. I assume this is hot break, and nowadays you would rather skim the scum instead of beating it back into the mash.

The first boil takes about an hour, where it gets a darker colour, until it is put back into the mash, to raise the temperature to 55 °C. Immediately, another decoction is drawn, but only boiled for 30 minutes, and then put back, with a resulting temperature of 67 °C. A third, thin decoction is then drawn, both taken from the top and taken from the tap (the mash tun has a false bottom, after all). Then it is boiled for 15 minutes, and put back, to reach a temperature of 75 °C. That whole procedure takes about 5 hours.

After that, the wort is drawn off. Hops are added while the first runnings are still drawn off, so this constitutes a first wort hopping. The overall boil lasts 2.5 to 3 hours. Fermentation is bottom-fermenting, as expected. What’s interesting is that after primary fermentation, the young beer is drawn into casks. A batch is spread out over lots of casks, though, so it takes about ten batches to properly fill all the casks. I presume this is to blend all the batches and to end up with a very consistent product over all casks even when the individual batches differ. Lagering period in the cellar is mentioned as lasting eight to ten months. That is indeed a keeping beer.

Beer brewed for the winter differs from this, as less hops are used, more wort is drawn off, and it’s boiled for a shorter period of time. There is very little maturation, and secondary fermentation for carbonation is initiated with Kräusen, and essentially happens in the publican’s cellar. This very much sounds like a running beer. Comparing with modern drinking habits, this is very counter-intuitive, as you’d expect the lighter beer to be brewed for the summer as a refresher, and the bigger beer to be made as a warming, boozy drink.

Augsburg

Apparently, the brewing methods in Augsburg were quite different from the rest of Bavaria. It starts with the malt: it is ground finely. The boiled hops of the previous batch are put on the false bottom prior to putting malt and then cold liquor over it. This is left for six hours. Boiling liquor is then added, and mashed for half an hour, and then more hot liquor is added, to bring it to 60 °C. This is then left for two hours. Sweet wort is then drawn off and put into the cooler. More hot liquor is added, and mashed for half an hour, with the resulting temperature being 67 °C. Then “all the goods” (I presume this means all hard matter) are put into the copper with hot liquor, and boiled for 45 minutes, then put back into the thin mash. The resulting mash is then at 86 °C. After some time, the cooled wort is put into the copper, the wort from the mash is also drawn off, hops are added, and the whole thing is boiled for two hours.

Fermentation is bottom-fermenting, and the beer is ready after about 2 months of maturation. Usually though, it is kept in large vats for a year to 1.5 years.

According to “Vollständige Braukunde”, beer brewed like that requires more cleanliness than the Munich approach, but has a higher yield and produces a milder beer.

Overall, a rather weird method in today’s standards. It seems like an infusion mash in the beginning, but with a final decoction, which would extract complex carbon hydrates, but leave the mash at temperatures where all amylases would have already been denatured, and no enzymes would be left to convert the starches into more simple sugars. Did the Augsburgers like their Blausud? (a Blausud is when a wort sample, mixed with an iodine solution, turns dark blue: it is an indicator that there’s still unconverted starches in the wort)

Prague

Prague’s brewing methods are described as similar to Munich, but with a fermentation “of the opposite kind”, which I assume means that in the 1830’s, Prague was still brewing with top-fermenting yeast.

Dough in starts at 46 to 50 °C, with an initial rest of nearly an hour. During that mash, more hot water is added to reach 59 to 63 °C. Then a decoction is drawn, brought to a brief boil, and then put back to get up to 67 to 68 °C. Then another rest of an hour follows. Wort is then run off, a Vorlauf if you will, with the express purpose to get rid of any grains underneath the false bottom. This wort is brought to a boil, and put back, to bring the temperature of the mash to about 84 °C. It is also emphasized that the grains must not be disturbed. Then a small portion of the wort drawn before is brought to a boil together with the hops, and the hops are taken out after 45 minutes. In total, the wort seems to get drawn off in batches and boiled, with the hops getting reused. A sparge is done, and the runnings are boiled with the hops from the previous boils.

Fermentation is done at 20 to 22 °C, so obviously top-fermenting. Maturation then happens in ice-cooled vaults for four to six weeks, and is served directly out of that cold environment. Yep, ice-cold beer.

Anyway, what we can see here is that the Munich style of mashing is a triple decoction, while Prague employed a double decoction.

Vienna

The crushed malt is doughed in with cold water, and mashed for two to four hours. Then cold wort is drawn off, and is brought to a boil together with liquor, boiling for 45 minutes. The froth on the top is skimmed off. It is then put back onto the malt, with a resulting temperature of 40 °C. Now this seems quite odd to me, as it would mean that a lot of the enzymes in the wort would be denatured quite early on.

Then something truly odd is done: wort is drawn off, and pumped back onto the mash. This is done for over an hour. A certain amount is kept in the copper, and again brought to a boil, but as soon as it starts boiling, it is added back to the rest of the mash, to increase temperature to 57 °C. Then more wort is drawn into the copper, again brought to a boil, boiled for 30 minutes, then put back into the mash. This is now left for 30 minutes at 72 °C. And then more wort is drawn off, again brought to a boil of 45 minutes, put back into the wort, and left for another hour at 82 °C.

Then wort is drawn off once more, and hops are added. When all the wort has been drawn off, the grains are loosened, and water of 56 °C is sprinkled onto it. The wort is boiled for 75 minutes, and some of it is put into the cooler. Then the second runnings are drawn into the copper, and boiled for another 90 minutes.

Then the wort is cooled to about 30 °C, and yeast is added. That’s a crazy pitching temperature. Fermentation is vigorous, and the young beer that is thrown out during the fermentation is collected and fermented in a separate vessel. This sound vaguely like the idea of a Burton Union, although with a separate vessel instead of recirculation. Shortly after fermentation has finished and the yeast has settled, casks of the young beer are sent out to the publicans. This all happens within 3 days.

So, in total, quite a strange process. Kinda like a decoction, except only thin decoctions are drawn. I wonder what prevented this from resulting in a Blausud, as well.

Berlin

This gets interesting now. Berliner Weisse. “The Art of Brewing” describes it as a beer made from 5 parts of wheat malt and 1 part of barley malt. That’s quite different from the 2:1 or 1:1 recipes that are listed in other old publications. “Vollständige Braukunde” mentions 20 parts of barley malt, 10 parts of wheat malt, and 2 parts of oat malt.

The finely ground malt is doughed in, and hot liquor is added to bring the temperature up 52 °C. This is left for an hour. Then wort is drawn off, and boiled with hops for 15 minutes. A thin decoction is drawn to interrupt the boil, and when this has reached 93 °C, it is put back into the mash, and left for 30 minutes, with a resulting temperature of 67 °C. Then another thin decoction is drawn, heated up to 96 °C, then both the mash and the decoction are put into the “tap-tun”, what sounds like a lautering vessel with a false bottom which is covered with straw (some sources say straw used in lautering was previously boiled in water). The resulting temperature in this tun is 75 °C. The wort is then drawn off, very slowly, though, and hot liquor is used for sparging. The overall lauter and sparge takes 7 hours, to produce a very clear wort. The wort is then put into the fermenting vessel, where yeast is added. Fermentation quickly begins, and the beer gets already shipped out to the publicans at this early stage.

In “Art of Brewing”, the author mentions that brewers thus have no yeast, and must buy it back from the publicans. To keep their yeast strains reasonably clean, they preferably buy from publicans that deal with other breweries than their own. The publicans also take care of bottling and storing the beer until it’s drinkable, which is usually after 14 days.

In total, this is quite the interesting process, as it does a kind of decoction, with the hop boil during the mash, and no further boil. Berliner Weisse is often described as a no-boil recipe, and people often ask themselves how the hops are added to it if there is no boil: directly during the mash. This way, the amount of isomerization of the alpha acids is easily to control, which is usually not the case if you added hops to a thicker mash that would undergo several decoctions.

Summary

In this article, I tried to summarize descriptions of different brewing techniques in German and Austrian cities at that time, in particular Munich, Augsburg, Prague, Vienna, and Berlin. It is interesting to see how the approaches completely differ, in particular the amount of decoctions that are drawn, what kind of decoctions are drawn, what is boiled for how long and in what order, and what temperatures are kept. With today’s knowledge and understanding of brewing and the microbiology behind it, it is fascinating to see what would be considered good practice nowadays, and what wouldn’t. The Munich triple decoction is a well-researched and well-documented method, as is the Prague double decoction. You would find descriptions of these in most modern brewing literature. The other methods, not so much. There, we find temperatures that would extract more tannins, or early thin decoctions that would denature lots of crucial enzymes early on in the brewing process. I seriously wonder how these brews went fine, and whether they produced Blausude.

An English Barleywine Recipe

About two years ago, my then girlfriend and I brewed our first Christmas beer. It was an oatmeal milk stout which, in retrospect, had just too many components and was a bit confused, but still drinkable. Right after finishing that, we had another great idea: why not brew a big beer that takes some time for aging, and serve that as Christmas beer in a year’s time? So the obvious style for us was English barleywine. I put together a recipe, we brewed it (and had a very chaotic brew day with too many stuck sparges and very low efficiency), bottled it, and after a year, it came out really nice. We kept a few bottles, and yesterday, we brought some of them to the Christmas beer tasting of the Berlin Homebrewing group.

This beer, now two years old, was well-received, and so I’m documenting the recipe for others to brew it and have the patience of a year or longer to actually get a great beer.

Grist:

  • 83 % Pale Ale Malt
  • 17 % CaraRed

Hops:

  • 2.5 g/l Target @ 90 min
  • 3 g/l East Kent Goldings @ 10 min

Two hour mash at 62 °C, then a 90 minute boil. Nottingham Ale yeast. OG was 22 °P, FG was 3.5 °P. 9.6% ABV. 65 IBU (calculated).

In my notes, I forgot to write down the alpha acid content of the hops that I used. In the end, it doesn’t really matter much, because the hop bitterness almost totally fades, and there is just some very muted, round bitterness there that accentuates the overall maltiness. Because of that, I’m not sure whether anything but a bittering addition really makes sense in the end.

After fermentation, we bottled the beer without any priming whatsoever, and no fresh yeast. It still took up some carbonation, which probably comes from tiny amounts of fermentable sugar left after the main fermentation, which was eventually, and very slowly eaten up by the yeast. After that, we sampled the beer at 3 months, 6 months, and 9 months age. Only at 9 months age, it started to taste nice, but really only reached its full potential after 12 months of bottle maturation. An additional 12 months added even more complexity, and that makes me very happy about this beer and the recipe.

A List of Yeast Banks and Producers for Homebrewers

Nowadays, homebrewers can choose from lots of different yeast strains from various producers and yeast banks. As a reference, I’m putting together all those that I know of and that explicitly cater towards homebrewers. I’m not including commercial or scientific yeast banks because they often do not sell their yeast in homebrewing quantitites for homebrewing prices. Also, if you know of any other places or companies that produce yeast for homebrewers, please let me know in the comments, and I’ll add them to the list.

Liquid yeasts:

Dry yeasts:

Update 2015-11-25:
Another dry yeast supplier I found: Brauwerkstatt

Update 2015-12-25:
Escarpment Labs has recently started making their yeasts available to homebrewers in Canada.

Update 2017-11-02:
Brewlab sells slants of a great variety of British yeast strains for GBP 6.00 per slant plus GBP 5.50 shipping within Europe (GBP 2.50 within the UK).

DMS and Boil Time

After writing about the sources of DMS in beer a few days ago, I stumbled upon another quite interesting paper from 1978 that discusses the influence of boil time on the amount of DMS in beer, titled “Control of the Dimethylsulphide Content of Beer by Regulation of the Copper Boil”.

In this paper, the authors put together two different lager malt blends. LMB 1 was designed in such a way that it was kilned at 65 °C, so that it would only contain inactive DMS precursor (see the previous article about active and inactive DMS precursors). LMB 2 on the other hand for kilned at 70 °C and later at 90 °C, so that it would contain substantional amounts of active DMS precursor. With both malt blends, worts of OG 1.037 (9.25 °P) were produced using a single-step infusion mash at 65 °C. The worts were boiled for different times (from 15 minutes up to 2 hours). Each of the worts were split, and fermented with different yeast strains, NCYC 240 and NCYC 1324. The two different yeast strains differ in the amount of DMS they produce: NCYC 240 produces a high amount, while NCYC 1324 produces a low amount.

What was noticeable in the results from the different boil times alone is that there a strong correlation of boil time with decreased amounts of DMS and DMS precursor in the worts. Consistently, LMB 1 had lower amounts of DMS and DMS precursor compared to LMB 2.

When the authors looked at DMS levels after fermentation, the results were quite clear, as well: a longer boil not only brings down the amount of DMS and DMS precursor in the wort, it also consistently reduces the amount of DMS in the resulting beer.

Influence of Boil Time on DMS Levels in Wort and Beer

The paper concludes that the DMS content in beer can be controlled almost impossible from other influencing factors through the right boil length and temperature. There is one exception though: if the DMS comes from another source than DMS precursor, a longer boil doesn’t reduce besides the normal evaporation.

Just like I hypothesized in my previous article, I will mention this again: I think that the literature is quite clear in that the wort boil has a large influence on DMS levels in beer, just like the specific metabolism of the yeast strain has a large influence, and that in the Brülosophy exbeeriment, the experimenters were just “lucky” in getting the right malt with only low levels of DMS and active DMS precursors, and a yeast strain with only low DMS production.

Sources of DMS in Beer

Quite often, when I run into an issue or a question related to homebrewing that is not answered in the usual homebrewing literature or forums, I turn towards scientific literature. One great example is the Journal of the Institute of Brewing, which makes its issues freely available, with literally more than a hundred years of back issues available.

When earlier today, Brülosophy posted lab results about their DMS exbeeriment, their closing statement irritated me a bit:

But, it’s just as possible our understanding of the relationship between DMS and boil length is simply lacking, that our access to modern technology, higher quality ingredients, and better knowledge about brewing processes has reduced the likelihood of problems brewers of yore had to worry about.

That sentence really made it sound like brewing science is only in its infancy. But that’s definitely not the case. Modern brewing science is lots and lots of organic chemistry, microbiology, and even genetics nowadays, so it would be hardly believable that we knew very little about DMS. I vaguely remember seeing an article about DMS on the mentioned journal, so I dug it up, and first posted a link to it in the comment section of that Brülosophy article. But then I thought, why not write about it? Because the paper itself is great.

So, the interesting that I took out of that article is that there are actually two types of DMS precursor. The paper distinguishes them as “active” and “inactive”. Both have different properties, and come from different sources.

“Inactive” DMS precursor is coming directly from the green malt. If you were to product wort from green malt, the precursor would be decomposed, and the wort would end up with large amounts of DMS, and still a certain amount of DMS precursor. During fermentation, parts of the DMS would dissipate through the gases being given off, while the DMS precursor would be metabolized by the yeast. The yeast wouldn’t make DMS out of it, though, hence why that precursor is called “inactive”.

“Active” DMS precursor is the type of precursor that is created out the inactive precursor during the kilning process. After wort production, there would only be a small amount of DMS in the wort, but still a relevant amount of “active” DMS precursor. During fermentation, that DMS precursor is metabolized by the yeast, which makes DMS out of it. Hence the “active”.

This has some interesting consequences. If the kilning can be done in such a way that no “active” precursor is found in the wort, the yeast will not produce any more DMS during fermentation, and the total amount of DMS in the beer is limited by the amount of DMS in the wort right before pitching. It can even be assumed that some of that DMS will be lost during fermentation. The authors suggest that the amounts of DMS formation during wort production need to be controlled, though. In their experience, it is easier to control DMS levels in beer if it’s derived from DMS precursor in the wort, as the final DMS level can be controlled by using a suitable yeast that keeps DMS production low.

And I think the last bit is the crucial point in the Brülosophy exbeeriment: it’s not that a 30 minute boil vs a 60 minute boil doesn’t have any impact for DMS levels, it’s just that both the specific qualities of the malt and the specific metabolism of the employed yeast do matter, and can have a large impact. My guess is: in the exbeeriment, exactly the “right” malt was used (Bestmalz Pilsner malt, apparently), combined with a yeast strain that only produces low levels of DMS (WLP029, a Kölsch yeast strain). And that perfect combination gave a result that made a 30 minute boil indistinguishable from a 60 minute boil in terms of DMS levels. That said, I would really like to see the same experiment done with a different malt (maybe a less modified floor-malted Bohemian Pilsner malt?) and a yeast strain known for greater DMS level, like a lager yeast. W34/70 comes to mind, for example.

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