Category Archives: Malt

Decoction and Undermodified Malt

In a discussion I recently about decoction, the topic of under-modified malt came up. Decoction mashing is typically associated with under-modified malt, as it helps break up the not yet fully dissolved endosperm of the malt with the help of boiling parts of the mash, while at the same time, the enzymes themselves have been dissolved in the thin mash.

Maybe let’s step back a bit, and talk about malt modification. To produce malt, grains are germinated by soaking them in water and giving them time to sprout. What happens is that the grain starts growing, all kinds of enzymes are produced, and the internal structures of the hard barley grain are modified to make it softer. Protein within that grain becomes soluble, and eventually, the grain starts to grow to become a new plant. Of course, that’s not what we what, the brewer wants to have the starch and the enzymes, so these are locked in by drying the so-called green malt. In order to determine how far this modification has progressed, the ratio of soluble proteins compared to the total amount of proteins is measured. You will find this in brewing literature als SNR (soluble nitrogen ratio) or Kolbach index, and it’s a percentage. A Kolbach index of less than 35 is considered to be poorly modified or undermodified malt, 35 to about 40 is considered well-modified, 41 to 45 is very well-modified, and over 45 is considered to be over-modified.

While decoction mashing is a remedy to deal with under-modified malt, some homebrewers even turn this around and say that under-modified malt would even be necessary for a decoction mash. In my opinion, using under-modified malt is not a necessity, and a decoction mash works equally well with well-modified malt, it just is not strictly necessary. If you want to do a decoction mash, use whatever malt you prefer, and don’t worry about it.

Now, if I as a homebrewer wanted to use an under-modified malt, which one would I buy? You sometimes read rumours that the Weyermann floor-malted Bohemian malt is poorly modified, but there’s not really much substantial information around. So I went out and tried to get some more detailed specifications on the base malts of two well-known German maltings, Weyermann and Bestmalz to see whether there’s any poorly modified base malt in their portfolio.

When I went through Weyermann’s specs to get the Kolbach index, I was actually genuinely surprised: all of their base malts are well-modified, some of them even specified to be potentially over-modified. These are the ones I had a look at:

  • Barke Pilsner malt: 36-41.5
  • Barke Vienna malt: 37-44.5
  • Barke Munich malt: 38-45
  • Pilsner malt: 36-42.5
  • Vienna malt: 37-45.5
  • Munich malt type 1: 37-46
  • Munich malt type 2: 38-47
  • Pale Ale malt: 37-43
  • Bohemian Pilsner malt: 38-42

Every  single malt was well-modified. What about Bestmalz? Same thing, really:

  • Heidelberg malt: 36-43
  • Pilsner malt: 36-45
  • Vienna malt: 37-45
  • Munich malt: 36-47
  • Munich (dark) malt: up to 47
  • Pale Ale malt: 36-45

What’s noticeable is that with both maltings, the darker kilned malts (Vienna malt, Munich malt) have a tendency to be specified to be more modified than the less kilned, paler malts like Pilsner and Pale Ale malt.

So, if I really wanted to brew with a properly under-modified malt, what options do I have? Not many. There is one product though that falls well into the under-modified range: chit malt, or as it’s called in German, Spitzmalz.

Chit malt is produced by kilning green malt that has barely sprouted. There is only a tiny tip poking out from the malt, indicating that modification has not gone very far yet. Because of this, chit malt is Germany’s loop hole around the prohibition of using unmalted grains according to modern beer legislation: because it’s technically malt, it can be used, but still has many of the properties of unmalted grains. Sometimes, you will also read about the use of chit malt being recommended to compensate for over-modified malts.

And that’s how you can approximate an under-modified malt for which you need to use a decoction mash: by mixing well-modified (but not over-modified) with a relatively large portion of just chit malt. Some sources on the internet say that you can theoretically use up to 40% of chit malt, and will be able to produce a reasonably good quality wort by employing a decoction mash. Papers on the TU Munich website suggest that even a 100% chit malt mash is possible.

Specification about chit malts are a bit sparse, especially when it comes to the Kolbach index. Bestmalz describes theirs as “up to 34”, but the lower threshold is not mentioned at all, so it can be extremely under-modified at worst. Weyermann stopped producing chit malt a few years ago due to lack of demand, and recommends CaraPils as an alternative if your intention to use chit malt was a better foam stability.

Given this information, I would say the best bet for homebrewers is to mix normal base malts with chit malt in amounts of 10 to 40%. Personally, I am not super keen on actually trying it, but if you insists on doing a decoction mash using under-modified malt, go for chit malt.

What was the colour of brown beer in the 19th century?

When working on my upcoming e-book about historic beers, one particular aspect of recreating historic beers crept through my mind: how similar or different are modern malts compared to malts that were produced 100 to 200 years ago?

The biggest improvements in malting technologies, in particular kilning, happened in Continental Europe within the last 200 years: while smoke kilns used to be widespread, Bavarian breweries started adopting modern, smoke-free kilns about 200 years ago, and in the 1830’s, Gabriel Sedlmayr and Anton Dreher brought back more knowledge about how to produce pale malts from the UK back to Continental Europe. The 1840’s were the beginning of pale lager beers which eventually became the world-wide standard for mass beer production around the world.

But one particular aspect kept bugging me: what did the colour of brown beers use to be like 100, 200 years ago? Here, by brown beer, I mean all beer made from kilned malt. The romantic notion is of course a deep brown beer, made from a highly dried malt, almost bordering on porter. But how can we get closer to the truth? It’s not like we can just look up photos of beers back then. Or can we…?

Well, not photos, but there’s a similar source: let’s take a closer look at art of that time. If we assume that painters who focused on a certain realism in their paintings took care of getting their colours right, then we can expect a realistic and reasonably consistent portrayal of the colours of brown beer. So let’s go through a few examples.

This first example is from a painting depicting a Bavarian pub scene in 1855. One man holds a glass of reddish-brown beer with an off-white head. It’s not clear whether the glass on the table also contains beer, but if it is, looks slightly paler due to the smaller size of the glass.This example shows a Stammtisch scene from 1872 with the waitress handing the customer a glass of dark brown, almost black beer, with a distinctly white head.This picture from 1877 again shows a bright, reddish-brown beer, almost bordering on a dark amber. …and the same goes for these examples from 1885, 1888 and 1912.  Noticeable in all three is a kind of glow, coming from a bright beer served in glassware, which, in my opinion looks mouthwatering. I would happily want to try one of these beers! The last two examples are slightly different: both from 1916, they show Austrian-Hungarian soldiers being served beer. The beer has an amber to golden colour, and is distinctly paler than in the other pictures that I showed here. Both are from brewery ads (the top one from the Hungarian Dreher brewery, the bottom one from Hütteldorfer brewery, Vienna), and mostly reflect the ongoing change in beer fashion at that time, while the previous examples are mostly from pictures painted by artists situated in Bavaria, where brown beer remained fashionable for longer than in most other places.

When we compare modern dark beers (in particular Bavarian ones) with those from 100 to 150 years ago, visually it seems like there is not really a difference. If anything, I’d say that the old beers in these examples may even have been a tad paler than the modern varieties.

Now what conclusions can we take from that, in particular for recreating historic beers? Well, the number one takeaway for me is that brown beers back then were mostly the same colour as today, which means that if I wanted to recreate an old beer recipe from that era, I could assume within reason that the colour of dark (Munich) malt nowadays is the same or very similar to how it used to be 100, 150 years ago. For historicity’s sake, the beer would also need to be as bright as on the pictures above: no haze in these beers. And finally, but that’s more of a minor detail: look at the drinking vessels at that time. While the Steinkrug (earthenware mug) is classically associated with historic beer of previous centuries, the art in the 19th century suggests that glassware must have been quite common for beer to be served in. And of course, a lot of the beer mugs have metal lids on them.

So, if you think about rebrewing some historic Bavarian brown beer, don’t worry about the malt, just use Munich malt as a dark base malt,  and make the beer bright and haze-free, and you’ll be fine.

“Chemistry In The Beer” – The Reinheitsgebot And Unmalted Grains

In a previous article in which I discussed the original source of the Reinheitsgebot, or purity law, I argued that the mention of barley instead of malt is of significance. Any use of unmalted grains is of course rejected by proponents of the purity law, and also the modern beer legislation, the Vorläufiges Biergesetz, codifies malted barley as the only allowed grain for bottom-fermented beer, and malt from any grains for top-fermented beer. In Germany, it is at the moment not allowed to brew beer that contains unmalted grains, adjuncts, or “Rohfrucht” as they’re called in German.

Already back in the 1960’s, the Reinheitsgebot proponents were fiercely against any change in German beer legislation and any attempts in harmonizing German legislation with EC legislation. The great fear was “chemistry” and “chemicals”. First there was the fear of hop extract, then there was the general fear of chemicals, culminating with the infamous Franz Josef Strauß warning about “chemistry in the beer”.

Even today, reinheitsgebot.de insists that the use of unmalted grains requires artificial enzymes (see answer to question 2) to convert its starches into fermentable sugars. Nothing is further from the truth. To explain why, I need to talk about why barley is malted in the first place.

The process is malting means that barley kernels are soaked in water. This starts the germination process, the barley basically starts the growth process. This produces enzymes that can convert starch into simple sugars, cell walls in the grain and proteins start to break down, the whole grain is being modified. If the maltster lets this process continue, whole plants would start to grow, and nothing would be left of the grain. That’s why after a few days, the so-called green malt is dried and kilned. Kilning at lower temperatures gets you a paler malt in colour, while kilning at higher temperatures gets you darker malts. The kilning process also destroys some of the enzymes. But brewers need these enzymes to later convert the malt’s starches into simple sugars during mashing. So it is the maltster’s job to produce malt that still contains enough enzymes.

The amount of enzymes in a certain amount of malt decides what amount of starches can actually be converted. This is called diastatic power. Paler malts usually have a higher diastatic power, while darker malts often have a lower diastatic power. Dark malt, like dark Munich malt (used to make dark-brown lagers, the classic Munich style of beer), has just enough diastatic power to convert itself, but not more. A lot of specialty malts, like caramel malts, dark kilned malts, and roasted malts have no diastatic power at all. They always require a certain share of enzymatic base malts to convert their starches.

Diastatic power for malts is specified in either Windisch-Kolbach units (°WK) or degree Lintner (°L). Conversion between the two is easy: °WK = (°L * 3.5) – 16. Usually, about 105-125 °WK (~ 35-40 °L) are necessary in a grist to fully convert all starches. Base malts can range from 140 °L (Pilsner malt) down to 40 °L (Munich malt) in diastatic power. A chart with typical values can for example be found here.

So, in order to brew with unmalted grains, there are two things that you need to make sure: first, you need enough enzymes by adding enzymatic malt into your grist, and second, you need to make sure that the enzymes can reach the starches. Some adjuncts thus need to be cooked or otherwise treated with heat to make the starch accessible. Flaked barley can be boiled, corn can be made into flakes (like cornflakes, except your breakfast cereal is fortified with a whole lot of other things that you may not want in your mash), oats can simply be rolled, while wheat can be torrified.

Calculating how much malt you need is easily. Suppose you have a base malt with 110 °L diastatic power. In total, you need 40 °L in your grist. That means you need at least 100*40/110 = 36.36 % of base malt in your grist, the rest can be unmalted grains. The lower your diastatic power, the higher your share of base malt, and with 40 °L Munich malt, you need 100*40/40 = 100% base malt.

So why is an all-malt grist still promoted? Because of historic reasons. Brewers back in the day could have easily worked with unmalted grains, and probably also did. But back then, even the malt wasn’t quite the sure thing as it is now: maltsters several hundred years ago didn’t have the ability to finely control, measure and evaluate their malt production. Historically, malts were often relatively dark (because it’s hard to finely control kilning temperatures), undermodified (i.e. some of inner structures weren’t properly broken down), and low in enzymes. These types of malt are hard to work with, unless you employ certain techniques. Decoction mashing, as practiced by German brewers for centuries, is one way of making the most out of malts that were badly modified and low in enzymes. In the 19th century, one of the big achievements of continental brewing was to learn how to produce pale kilned malts, but the decoction mashing tradition remained.

British brewers on the other hand, who had known how to produce pale malts for much longer, have traditionally employed a mashing regime which is nowadays often called a single-step infusion mash. The grist is infused in water and rested at a certain temperature. Because the malt is better modified, and relatively rich in enzymes, it can easily convert all the starches without requiring decoctions to make it more accessible. The same technique is employed by most homebrewers nowadays due to the high quality of malt, as well as commercial brewers that try to avoid energy-intense decoction mashes. Adjunct brewing is a well-researched topic in brewing science, and even German scientific brewing literature contains plenty about it.

So, from a purely technological point of view, there is no argument against the use of unmalted grains when producing wort. With some care, adjuncts can be easily used without requiring any artificial enzymes or other “chemistry”. Brewers can also benefit from a wider range of base materials, as unmalted grains often impart slightly different qualities in the beer compared to their malted equivalents. It is not bad per se, nor is it artificial. Rejecting unmalted grains is dogmatism, in my opinion, as it provides and ensures no quality in the beer, but instead just arbitrarily restricts brewing and thus variety.

In the end, the prohibition of unmalted grains in German beer is also an insult to German malting. German maltsters produce a wide range of all kinds of base malts and speciality malts, exactly matching very strict specifications in colour, kernel modification, friability, protein content, diastatic power, and a whole lot of other properties. At the same time, German legislation specifically disallows German brewers to build upon some aspects of this high quality work. And the proponents of the Reinheitsgebot even support that, even though it makes no sense other than to bring up that bogeyman that is “chemistry in the beer”.

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.