Category Archives: Hops

When did hop alpha acid become relevant in recipe formulation?

This is one question that itched me a lot is the matter of hops and their contribution of bitterness in historic beers: when did the alpha acid content of hops become relevant in beer recipe formulation?

While the topic of bitterness in beer and the various contributing factors is a complex one to be discussed at another point, it is universally recognized that iso-alpha-acid, the isomerized form of alpha acid, is a major contributor to the overall bitterness of a beer. This isomerization happens when boiling the wort with hops. Even the quantification of bitterness in beer, often noted as IBU, International Bitterness Units, is essentially a determination of the amount of dissolved iso-alpha-acid by employing spectrophotometry.

One conclusion of the observation of the relationship between iso-alpha-acid and bitterness is that the higher the amount of alpha acid in a particular crop of hops is, the higher the contribution of bitterness will be in the resulting beer, assuming the same boil times and all. Brewers nowadays take the amount of alpha acid in hops into account when formulating beer recipes, and using formulas like Tinseth, Rager or Garetz, attempt to approximate the expected bitterness. Of course, this is very much only an approximation: lab analyses have shown that the calculated IBU can diverge quite a bit from measured IBU, in particular in amounts that are beyond the maximum solubility of iso-alpha-acid in aqueous solutions.

But what does this have to do with historic beer? Quite a lot: due to the lack of analytical methods to determine the bitterness contribution of a particular hop crop, it was essentially unknown how bitter a beer would end up with a new crop until it was brewed and taste-tested.

Depending on various factors like the weather, crops of the same hop variety grown in the same hop garden in different years can yield different amounts of alpha acid.  Chinook hops from 2016 can have e.g. 11.6 %, while the 2015 crop has 12.8 %, the 2014 crop 12.0 %, the 2013 crop 13.7 %, and so on. This aren’t just made-up numbers, I took these from the historic data of Chinook hops as provided by a German online homebrewing store.

When looking at the relative variability of the alpha acid content, you roughly get a +/- 10 % variation over the course of several years, which would also reflect the same in the overall bitterness contribution.

Now, in the context of historic beers, this variability is a lot more dramatic: early hop varieties and local land races are usually low in alpha acid. If we had the same absolute variability in alpha acid content in a land race as with Chinook in the example above, the impact on the relative variability would be much greater. Let’s look at another example: Hersbrucker Spät from 2016 with 3.2 % alpha acid, 2015 3 %, 2014 2.3 %, and 2013 a staggering 1.8 % alpha acid content. In terms of relative variability, this is more in the range of +/- 30 %.

In pretty much all historic recipes from the 18th, 19th and first half of the 20th century, hop dosage is usually specified in weight per resulting beer, for example gram per hectolitre or pounds per barrel. If I were to brew a simple Munich Lagerbier according to typical first half of the 19th century gravity and hopping rates, a variability between 1.8 and 3.2 % alpha acid makes the difference between 27 IBU on the low end and 47 IBU on the high end. That’s about the difference in bitterness between e.g. a malty brown ale (e.g. Sam Smith Nut Brown Ale allegedly has 31 IBU) and an aggressively hopped Pilsner-style beer (Schönramer Pils allegedly has 45 IBU).

I actually haven’t found much evidence how brewers used to counteract these problems, but I have two theories:

Bavarian brewers employed blending methods prior to lagering their beer: several batches of beer were fermented one after the other, but were then evenly split up between a relatively large number of lagering barrels. This was done for consistency reasons, and would have allowed the brewmaster to adjust the hopping rate of the different batches according to the outcome of the first batch or first few batches.

To a certain extent, brewers also had a relatively good understanding how hops brought preservative qualities to the beer. In some literature, e.g. Ausführliches Lehrbuch der Bayrischen Bierbrauerei mit besonderer Berücksichtigung der Dickmaischbrauerei by J.S. Schorer (published in 1863), different hopping rates and blends of hop varieties were proposed depending on how long the beer was to be lagered, and how late in the year the beer was to be served, in order to compensate for the slowly warming beer cellars (this was before modern refrigeration, when beer was still lagered in ice cellars). Some of these hop blends suggest blending hops from the latest harvest with older hops from previous years. Old hops still provide preservative qualities, but due to the degradation of the alpha acid content, don’t contribute nearly as much bitterness as younger hops. This effect is used even nowadays in Lambic brewing, where relatively large doses of aged hops are used.

But this still hasn’t answered the original question. So I went out and searched a bit. To cut this a bit short, I was not able to find a proper answer. I was not even able to find out when alpha acids were discovered, or when iso-alpha acid was first recognized as contributor of bitterness. But I was nevertheless able to at least find something:

An early analysis of different hop varieties regarding their alpha and beta acid contents (back then often called “alpha resin” and “beta resin”) are the two papers called “REPORTS RECEIVED FROM BREWERS ON RECENT BREWING TRIALS WITH CERTAIN NEW VARIETIES OF HOPS” by Prof. E. S. Salmon and H. H. Glasscock, M.Sc. (published 1944) and “REPORTS RECEIVED FROM BREWERS ON RECENT BREWING TRIALS WITH CERTAIN NEW VARIETIES OF HOPS; II“, by Prof. E. S. Salmon and Dr. A. H. Burgess (published 1947). These papers refer to analyses going back as far as 1932, and not just of new varieties as the titles would suggest, but also Fuggles from Worchestershire and Mid-Kent and Goldings from Mid-Kent and East-Kent. In case you’re wondering, “new” varieties discussed were hops like Brewer’s Gold, Quality Hop [sic!], Brewer’s Favourite, Bullion, Fillpocket, and Brewer’s Standby.

From what I could see from scanning the literature of that time, the analysis of different types of alpha acid was still an active research topic and the 1950’s and probably beyond that. It have not been able to find a definitive point in time where the relationship between iso-alpha-acid content and bitterness contribution was discovered or picked up as a tool to determine hop dosage sizes. So unfortunately, this question remains unanswered as of now.

Hops used in Vienna Lager

Two  years ago, I did some research to put together a recipe that was meant to closely match what a Vienna lager in the 19th century would have looked and tasted like.

About a year ago, I also discussed the state of Austrian hops and how the hop growing industry had changed over time. In that article, I mentioned that Kleinschwechater Brauerei used to own land in Michelob in Bohemia, close to Saaz, where the brewery grew barley and hops. Due to the geographical closeness, I made the point that most likely Saaz hops or a very closely related landrace would have been grown there.  But so far, I did not have any conclusive proof that Kleinschwechater (later Schwechater) Brauerei indeed brewed with Saaz hops.

That changed a bit when I visited the Schultze-Berndt library located at VLB and curated by the Gesellschaft für Geschichte des Brauwesens (society for the history of brewing technology) a few weeks. When doing some research for my English-language book on homebrewing historic beer styles, I stumbled upon a Festschrift regarding 100 years of brewing Vienna lager, aptly named “Schwechater Lager”. While not having that much content, it still had some bits and pieces that gave away some information, including the beautiful water colour illustrations.

One image in particular contained something very interesting: pictures of huge stacks of hop bales. 

These hop bales clearly show the marking “SAAZ”. Assuming that this picture accurately shows the hop storage facilities at Schwechater brewery, we now have a direct connection showing that Schwechater has been using Saaz hops. The text around it mentions that the brewery has been covering their demand using hops from Saaz, and praises Saaz as one of the best hop growing regions in the world. Unfortunately, no time frames are mentioned, so while all this information was certainly true for their brewing in the late 1930’s and early 1940’s, we cannot yet make the direct connection that Vienna lager in the 19th century must have used Saaz hops.

So let’s go a bit further, into the less colourful but more number-laden territory of raw statistics. In 1891 (that’s the earliest that I could find), Bohemia had 10317 hectares of hop growing land, producing an annual output of 77540 Zentner (1 Zentner = 50 kg in Germany, therefore 3877 tons). At that time, the total hop growing area of the Austro-Hungarian Monarchy was 14850.5 hectares (divided into the regions of Bohemia, Galicia, Styria, Upper Austria, Moravia and Carinthia), and the total annual output was 117534 Zentner (5876 tons). So for the whole of the monarchy, Bohemia produced almost 66 % of all its hops, on almost 70 % of its acreage allocated to hop growing.

This trend of Bohemia being the dominant hop grower within the monarchy continued in the years after as late as 1918, and Bohemia’s dominance even grew larger as other hop growing areas declined further: in 1913, Bohemia’s hop output was 73.8 % of the monarchy’s total output, with 75.8 % of the total hop acreage, while in 1914 it was a staggering 87.7 % (85.2 % of the total hop acreage). The stark increase in share in 1914 is due to a complete failure in Galicia for that year, most likely due to World War 1 and Austria-Hungary losing the Battle of Galicia.

So, just by looking at the pure numbers, we can deduce that there was a very high likelihood that most breweries bought their hops from Saaz. Again, this is not definite proof, but it points even more towards the direction that hops from Saaz were used by Schwechater brewery, and possibly most other breweries at that time, especially since Saaz hops were the highest priced ones in Germany and Austria at that time.

On a side note, the hop production of Bohemia at that time up as late as the late 1930’s was so strong that Germany’s annexation of the Sudetenland in 1938 pretty much doubled Nazi Germany’s acreage and overall amount of hops produced.

The Demise Of Upper Austrian Hop-Growing

In a previous article, I discussed the history and current state of the hop-growing industry in Austria. Recent finds in the Upper Austrian state library allow me to expand on this topic, in particular on hop agriculture in Upper Austria, in particular in Mühlviertel.

Hop-growing has a great industry in Upper Austria. The earliest mention of hop-growing dates back to 1206, and there’s always been hop-growing all over the country, but especially so in the Mühlviertel, the northern-most part of Upper Austria, and the Innviertel, the western-most part which used to belong to Bavaria until 1779 and was heavily influenced through the hop-growing industry there. Even though Austria was always overshadowed by the much larger hop-growing regions in Bavaria and Bohemia, Upper Austrian growers managed to produce good quality that at least was able to satisfy local demand, and export to a certain extent. One source mentions during the time of the American Civil War, hop exports from the US to England essentially ceased, which allowed some Upper Austrian hop growers to enter the English market at least temporarily.

But the dominance of Bavaria and Bohemia got bigger and bigger, while the crop areas in the Mühlviertel kept shrinking quite massively: while in 1927, there were still 307 ha of hops being grown, it was a measly 32 ha in 1936. Attempts to counter this in the 1920’s failed due to lack of funding, and also due to difficulties to compete with Bavarian and Bohemian hop products.

In the previous article, I mentioned that in 1939, the remaining hop gardens were ordered to be uprooted by Berlin. Without context, it may seem nonsensical to just get rid of a local agricultural industry, but there’s actually a geopolitical reason behind it.

After the “Anschluss” of Austria, the Upper Austrian hop-growing industry actually hoped to be able to revive and increase the acreage of hops with the help of the German beer industry. But in October 1938, the Sudetenland, the then mostly German-speaking areas of Czechoslovakia, were annexed by Nazi Germany after the Munich Agreement. Since this included the hop-growing regions of Saaz/Žatec and Auscha/Úštěk, Germany suddenly had an absolute over-abundance of high-quality hops for its beer brewing industry.

This was the demise of hop-growing in Mühlviertel: with the vast majority of European hop-growing regions under German control, it made at that point no sense to further invest into the Mühlviertel, and so it was decided to end hop-growing altogether there.

In some ways, the Munich Agreement was the demise of Upper Austrian hops. With it, the land races of that area were lost. Only after World War 2, hops were reintroduced, but this time, English and later German varieties. Nowadays, Malling, Styrian Golding, Aurora, Perle, Tradition, Spalter Select and Saphir are being grown there.

The State of Austrian Hops

DoldenEspecially when discussing historic Austrian beers, obviously Austrian hops, or to some extent, Cisleithanian hops, are often discussed. A lot has happened in terms of hops over the last 100 years in Cisleithania (the Austrian part of the Austrian-Hungarian empire after 1867), and I’d like to give a bit of an overview about it.

Historically, hops were grown only in certain regions of Cisleithania. The largest of these areas were the Saaz (which now belongs to the Czech Republic), the Mühlviertel (part of Upper Austria), the Waldviertel which lies in Lower Austria and is adjacent to the Mühlviertel, and Lower Styria, which now mostly belongs to Slovenia. In the nowadays Austrian part of Lower Styria, only in Leutschach there is still a hop-growing industry.

Each of these areas had their respective land races of hops. A land race is simply a variety of hops that was growing locally and was eventually domesticated, and they’ve traditionally been named after the respective local regions. Hence Hallertauer, Hersbrucker, Spalter, Tettnanger, Saazer, and so on.

Wait, why do only Saaz hops appear in that list of land races, but none from the Mühlviertel or Lower Styria? Because, as far as I was able to find out, Saaz hops are the only land race left of all the local hop varieties that were grown in Austria in the 19th century.

The first “victim” were the hops in Styria. The main hop variety for quite some time now is Styrian Golding resp. Savinjski Golding, which was introduced to Styria only relatively recently. The book “For The Love Of Hops” by Stan Hieronymus (p.167) claims this was in the 1930’s after Slovenian hop fields were destroyed by a disease and that the replacement was Fuggles misidentified as Goldings. slovenianhops.si claims that Styrian Goldings is a descendant of Fuggles and that it was introduced in the early 19th century. This seems highly unlikely, as Fuggles was isolated, categorized and named only in the 1860’s/70’s. But what seems to be secured is that the local land race in Styria was not resistant to a hop disease (some say powdery mildew), while the imported Styrian Goldings were, and thus completely overtook the local industry.

What I keep reading, most of the time without any source, is that Styrian Goldings was Anton Dreher’s favourite hop variety. This is total bollocks, as Anton Dreher died in 1863, before Fuggles was even released to the public. Also his son, Anton Dreher the younger, died in 1921, before Styrian Goldings started to be grown.

Hop growing in the Mühlviertel goes back several hundred years, with the first historic mention in 1206. The peak of hop production was in 1880. But in 1939, the hop industry came to a stand still, as Berlin ordered all hop farmers in Mühlviertel to destroy their plants. The hop industry was dead in the Mühlviertel until after World War 2. The “reforestation” of hops was initially done with English hops. That’s how the Malling hop variety made it to Austria, where it is still grown to this day. Later, Styrian Golding and Aurora were added, as well as Perle, Hersbrucker, Spalter Select, Saphir, and Tradition. The original land races don’t exist anymore, and aren’t grown commercially anymore. The same also goes for the Waldviertel, as it is geographically adjacent to the Mühlviertel, and both regions hop marketing and sales efforts have been combined since the early 1950’s.

That leaves the Saaz hops. Unlike the two previous regions, the local land race of hops was never destroyed by hop diseases or ordered to be removed. Due to its rather unique aromatic qualities and the widespread use in Czech beers, Saazer hops are still widely grown and have soared in popularity world-wide. It’s the only Cisleithanian hop land race left that is still commercially available to brewers, and in my opinion, the only good choice for historic Austrian beers.

This may seem counterintuitive at first, as you wouldn’t immediately associate Czech hops with Austrian beer, but there’s a very direct connection between Saazer hops and Austrian beer: Anton Dreher and the Kleinschwechater Brauerei. This brewer, well-known for the invention of the Vienna lager, a very early and (for that time) pale continental lager beer, used to own land in Michelob near Saaz, where he’d grow hops and barley to stay independent from the then relatively volatile market. It is safe to assume that the hop variety grown there is the local land race, and that he’d use the self-grown hops in his own beers. A year ago, when I tried to retrace the history of Vienna lager and the appropriate ingredients, I used Saazer hops as well, and their spiciness worked quite nicely in combination with the Vienna malt. Even a modern Austrian commercial recreation of that historic beer, Ottakringer’s “Wiener Original”, uses Saaz hops.

In any case, it would nevertheless be very interesting to learn whether any of these older land race hops have somehow survived in the seed bank somewhere around the world. If they do, then reviving them, like the historic English Farnham White Bine hop variety, would certainly be possible.