We humans are creatures of tradition. We revere the ancient, the history, and the old. It’s no wonder when a group of smart marketing folks start plastering buzzwords that imply an inkling of primordial origin to a food product, we enshrine them - sometimes catapulting the seemingly ordinary into fame.

A hop cone from Hallertau, Germany.

Is that necessarily a bad thing? I don’t think so! No two regions are ever the same - Chardonnay, the grape that makes for age-worthy sparkling wines in Champagne, will not grow the same as, say, in the warmer regions of the Napa Valley, where big powerful wines are oaked. When we see a Bordeaux appear on the dining table, we associate the wine to certain tastes and characteristics, because of the permitted grape varieties that make up the Bordeaux blend. 

Only a few varieties of grapes are permitted to be in Bordeaux blends. Source: Wine Folly

So who exactly are the four noble hops? The four noble hops refer to four hop varieties originating from Germany and now Czechia that have ascended to nobility, partly because brokers and hop traders crowned them as such to highlight the origin of where the hops are grown. According to hops scientist Adrian Forster, the term “noble hops” was coined roughly in the 1970s and 1980s, when what Germans called the “fine aroma hops” got translated to “noble aroma hops” and then truncated to “noble hops”. In short, there is no scientific definition that made this hops noble, but instead a (largely) general consensus amongst hop traders and brewers.

A vintage Pilsner Urquell advertisement. Source: Open Library

However, this isn’t to say that the hop varieties didn’t earn their stripes (or vines) so to speak. The four hop varieties have been carefully selected and propagated for centuries - expressing the terroir and influencing beer-brewing styles in German and Czechia. Hence, even though these four varieties can be found growing everywhere else in the world, the hops grown in their legacy hometowns command a higher price. 

So, here are the four noble hops: Hallertauer Mittelfrüher, Tettnanger (sometimes called Tettnang), Spalt (sometimes called Spalter), and Saaz. Hallertauer Mittelfrüher is the odd one out, as research suggests that Tettnanger, Spalt and Saaz share a common lineage or were at one point crossbred, hence the latter three form the Saazer group. 

Hop images from Hopsteiner.

Tripping on acids 

Before we go in depth on the characteristics of the hops, let’s first geek out a little on the chemistry of hops. 

Hops introduce two elements into the beer: bitterness and aromas. The alpha acids, found in the lupulines of the hops, contribute the bittering element to the beer. The essential oils of the hops are what contribute aromas of fruit, flowers or spice into the beer.

The lupulines are the yellowy portions of the hop cone. Sierra Nevada has a interactive infographic on the anatomy of a hop cone.

Here’s where things get a little bit technical. There are two categories of hops: bittering hops and aromatic hops. Bittering hops contain more alpha acids by dried weight (expressed as a percentage), while aromatic hops contain less alpha acids and more esssential oils. Some hops are dual-purpose hops. 

For the homebrewer, when purchasing hops online, suppliers typically indicate the alpha acid weight percentage.

A few examples of alpha acids include humulone, cohumulone and adhumulone. These acids are also responsible for some of the antimicrobial properties that preserve beer for longer as well. To extract these alpha acids, the hops need to be boiled in the wort, with longer boil times extracting more alpha acids. The high heat will cause the alpha acids to isomerise (essentially, changing the chemical molecule while retaining the same constituent atoms) into iso-alpha acids, which are then soluble in water and hence give beer its bitter flavour. 

An example of humulone isomerisation when beer brewing. Source: Bland et. al. (2015)

On a chemical level, there has been some research conducted on alpha acids, with varying levels of understanding on what each alpha acid really does (in terms of the flavours they contribute to the beer, how bitter they are, what antimicrobial and anti-cancer properties they have, etc). For the brewer, the weight percentage of alpha acids in beer helps them determine how bitter the final beer will be, which could be represented on an IBU scale (international bitterness units) to convey to consumers and beer drinkers. 

4 Pines Brewing Company, for instance, indicates their IBU to be 15 units on their Pacific Ale.

 On a similar vein, there are also beta acids (lupulone, adlupulone, colupulone, and prelupulone) in hops - the less well understood sibling of alpha acids. They do not contribute as much bitterness to beers as their alpha sibling right form the get go (look up this published paper on how it compares to alpha acids in terms of intensity) -  however, as a beer ages, the alpha acids break down and lose their bitterness while beta acids oxidise in the beer and become bitter. 

How alpha acids and beta acids differ. Source: Schindler et. al. 2019

For the aspiring brewer, beta acids are not usually explicitly labelled when buying hops, but  a quick search on the weight percentage of beta acids could be important to consider if a beer is to be aged or kept for a long while. Similarly, brewers could also look out for the alpha acid to beta acid ratio: a close 1:1 ratio may make a beer overtly bitter at the start but help with long term storing, whereas a 2:1 ratio could give a certain profile of bitterness and flavour that is more desirable in the beer.

Hallertau Tradition, a hybrid of two hop varieties, has quite a close 1:1 ratio of alpha and beta acids. Source: BSG Craft Brewing. 

To wrap up this discussion on alpha and beta acids in beer, there has been some discussion on how humulone and cohumulone affects the bitterness of the beer. Both being alpha acids, it has been said that humulone has a “softer”, rounder bitterness, while cohumulone gives a “sharper, more unpleasant” bitter sensation in the beer. Much of hops and beer research have painted cohumulone as the bane of beer bittering, and hop geneticists have strived to produce hops with low cohumulone concentrations. I’m no beer brewer, neither am I an organic chemist nor a hop expert - but here’s an experiment done by a brewer to tease out the differences. 

Brülosophy's experiment on humulone and cohumulone yielded quite some insights - testing the commonly-held ideas of what bitterness is desirable in a beer.

Essential oils and where to find them

Now, moving on to essential oils - here is where hops varieties get much of their personality from. The essential oils of hops give beer a whole diversity of flavours and aromas - from fruity and floral (e.g. contributed by alcohols, esters, sulphur-containing compounds), spicy, woody and herbal aromas (sesquiterpenes, oxygenated sesquiterpenoids), to “green” vegetal ones (aldehydes).

A few examples of essential oils found in hops. Hydrocarbon oils are less soluble in water than oxygen containing oils. Souce: Pats Pints

In a broad sweep, aromatic hops contain more of these essential oil, and scientists are discovering a broader spectrum of these essential oils with more research (turns out, the study of essential oil in hops is dizzyingly difficult, with around 1,000 volatile compounds currently being discovered). While the variety of the hop does play a part in determining what essential oils and hence flavours are extracted into the beer, climate, terroir and a whole host of other factors in relation to where and how it is grown will affect the essential oil concentration and variety as well. 

As a general rule of thumb, the essential oils in these hops are delicate and prone to being lost if it is boiled for long periods of time in the wort, hence, are added slightly later in the beer production process. Here’s the counterintuitive segment of this article: dry hopping and wet hopping. Contrary to what their names suggest, no, they are not opposite processes of each other - instead, they refer to the state of the hops when it is used in the beer making process… sorta. Dry hopping refers to adding dried hops, usually in pellet form, into the wort after it has boiled. This ensures that not too much additional bitterness is introduced into the beer, while the hops can still perfume and add flavour to the beer. 

 Dry hopping in a fermentation tank. Source: Sierra Nevada

Wet hopping refers to adding freshly harvested hop cones into the beer - be it before, during, or after boiling the wort. While it is logistically more challenging to wet hop beer as freshly picked hops, without drying, can lose its freshness and expire quickly, some brewers choose to do so to impart a “greener” taste to the final brew. Additionally, when hops are dried into pellets, some of its essential oils could be lost due to oxidation and heating. 

Wet hopping.

What makes the noble, noble?

Long, jargon preamble aside, what makes the noble hops, well, noble? As we mentioned earlier, the four noble hops refer to hops that have been traditionally used in German and Czechia (and by extension, to other European countries as well). These hops tend to have a low alpha acid percentage, meaning that they do not infuse the brew with too much bitterness. This leads to the classical pilsner and lager styles of beer that the world loves so much. 

Lager and Pilsner.

Remember how we talked about beta acids oxidising over time? An interesting trait of the four noble hops is that they have a close 1:1 ratio between alpha acids and beta acids. Some beer and hop researchers theorise that the noble hops played a huge role in lagering - lager meaning “storage” in German. Back in the days, hops were added to beer to improve shelf life - but lager beers were stored and left to ferment in cool caves before drinking. Due to the somewhat higher beta acid component of beers it could have kept beers fresher and bitter for a longer time. 

While this could be an oversimplification of the beer styles in Europe, the beers in Belgium, Germany, Czechia and the surrounding countries tend to have a floral, bitter and spicy hop profile in their beers, as compared to more modern IPA contemporaries that feature a juicer, fruitier profile. It is important to note too that terroir really matters - these varieties of hops are now grown all over the world, but just like how Champagne grapes are prized because they are from Champagne, the hops and where they’re grown will influence the acids, essential oils and ultimately value of the stuff. 

A Bohemian hop harvest in 1898. Source: Amstein

Now, let’s dive into each and every member of this hoppy quartet. 

[Do take note that there are varying figures for the alpha and beta acid content of the listed hops. I took the alpha acid figures from Untappd’s article, and the beta acid figures from Hoplists’ articles.] 

Hallertauer Mittelfrüher

Let’s start with the odd one out of the list first. Hallertauer Mittelfrüher does not share the same common ancestor or genetic lineage as the other three hops. The origins of this variety is largely unknown - only that this variety was found in the wild and then subsequently cultivated by the locals living in the area (also known as a “landrace”). 

Source: Hopsteiner

While the variety is grown throughout Germany, the Hallertauer Mittelfrüher refers to the Mittelfrüher variety grown in Hallertau, Bavaria, Germany. Hallertau, the largest continuous hop planting area in the world, has been known to cultivate hops since 768 AD and today produces 80% of Germany’s hops. 

Map of Hallertau. Source: Wikipedia

Most brewers and hop breeders characterise the Hallertauer Mittelfrüher for having a spicy, floral and earth aromas. Currently, The Hallertauer Mittelfrüher is in decline due to its susceptibility to verticillium wilt and low yields, and a few breeders have been producing crossbred offspring to improve the resilience of this variety.

The Hefe Weissbier from Weihenstephaner is a beer that uses the Hallertau Mittelfrüher, according to Silly Sir Brewing Co.

Origin: Hallertau, Germany 

Use: Aroma 

Alpha Acid: 3.5 - 5.5%

Beta Acid: 3.5% - 4.5%

Aroma Notes: Spicy, floral, earthy 

Beer Styles: Lagers, Pilsners, Belgian ales, European ales

Tettnanger

Source: Hopsteiner

Tettnanger gets its name from Tettnang, a town at the South of Germany that resides close to Lake Constance (or Bodensee) and the Swiss border. The environment near the lake makes it a suitable place to grow Tettnanger, growing up to 5% of Germany’s total hop production. This variety is popular overseas - mainly due to its hardy nature and resilience against diseases. Be warned though - much of the hops on sale are actually Tettnanger crossed with Fuggle, an English hop variety. Hence, some hop suppliers differentiate by indicating Tettnanger Tettnang instead. This hops is also widely grown in Hallertau as well. 

Source: Wikipedia

Many have compared the characteristics to be quite similar to Saaz and Spalt, further down in the list. However, the hops have been known to be more balanced and subtle in its floral, herbal and mild spicy aromas, hence it has found use in both as a bittering hop and as an aromatic hop. 

The Rothaus brewery uses a blend of hops from Hallertau and Tettnang.

Origin: Tettnang, Germany

Type: Dual purpose (aroma and bittering) 

Alpha Acid: 2.5 - 5.5%

Beta Acid: 2.8 - 5.3%

Aroma Notes: Herbal, floral, mild spice 

Beer Styles: Pilsners, lagers, ales, triples, saisons, wheat beers

Spalt

Image Source: Hopsteiner

This hops, unsurprisingly, gained its name from where it is grown: Spalt, Germany. The town of Spalt is renowned for producing beer and hops since the 14th century. In 1538, the town of Spalt was the first to receive the German Seal of Hop Quality: where an area is known to produce high quality hops from its terroir. The seal not only recognises the area which the hops are grown at, but also the particular variety as well. Nevertheless, there could have been some crossbreeding between Saaz hops and Splat hops.

Source: Minnesota's Free Country

Spalt, also known as Spalter, should not be confused with Spalter Select, a 1993 variety that crossbred Spalt with Hallertau Mittelfrüher. The aromas of Splat are known to be woody and peppery alongside ripe banana. Splat has been used quite extensively in altbier by German brewers, an old German style of beer originating from Düsseldorf that is usually copper in colour and sports fruity aromas.

Chances are, the altbiers from Düsseldorf contains Spalt hops.

Origin: Spalt, Germany

Type: Aroma

Alpha Acid: 2.5 - 5.5%

Beta Acid: 3.0% - 5.0%

Aroma Notes: Woody, peppery, banana

Beer Styles: Lager, pilsner, bock, kölsch, altbier

Saaz

Image Source: Hopsteiner

Now, this hops didn’t originate from Germany. Instead, it originates from Czechia (Czech Republic), from the Czechian town of Žatec (Saaz in German). This variety of hops has been around since the 8th and 9th century, where in the town of Žatec, the conditions to grow the hops are exceptionally superb. The hops were of such value that when Charles IV, who inherited the kingdom of Bohemia in 1346, made the export of this hop variety outside of Bohemia punishable by death. Nevertheless, this variety has since spread and been cultivated outside of its original lands. 

Image Source: Brew Engine

Saaz is incredibly popular for its low alpha acid percentage, making it ideal for adding a very subtle bitterness to the hops while perfuming it with aromas. The Saaz variety is only officially registered in 1952, where it has underwent cloning trials to improve its resistance to mildew and wilt. Saaz is also widely known to impart its mildly characteristic floral, herbal and spicy taste to beers, and is most notably known for its use in Stella Artois. Some specific aromatic notes include  tarragon and lavender.

Pilsner Urquell, from Czechia, also uses Saaz hops.

Country of Origin: Czech Republic

Type: Aroma

Alpha Acid: 2.5 - 4.5%

Beta Acid: 4.0% - 6.0%

Aroma Notes: Mildly floral, herbal, spicy, sweet

Best Beer Styles: Bohemian-style lager, pilsner

Somewhat noble hops..? 

Of course, for a list that, at least from a scientific point of view, seems rather arbitrary, there has been debate on what should and should not be on the list. Most of the general consensus settled around these four, but there are some hop growers and brewers who claim that the list should be extended. 

After all, the royalty has its fair share of troubles. Not only is available land for growing these hops diminishing, climate change, disease and usually low yields has left hop growers seeking for alternatives. Many of these nearly-noble hops do share similar characteristics - aromatic, low alpha acid and a near 1:1 ratio of alpha and beta acids. Also, some of these varieties have had their fair share of time and use on the Europe continent as well, hence the argument. 

Here’s a non-exhaustive list of almost noble hops: 

• Fuggles: The quintessential English hop variety was discovered in a hop yard belonging to George Stace in Kent county. The hop was named after Richard Fuggle of Benchley.
  
  
• East Kent Golding: Another hop that originated from the UK, its origin story is somewhat similar to Fuggles. The original variety was found in someone’s hop garden in East Kent. No one really knows whom the hop is named after.
  
  
• Hallertau Hersbrucker: Also originating from Hallertau, Germany, this hardier hop is often used to replace the Hallertau Mittelfrüher.
  
  
• Strisselspalt: A hop originating from supposedly Strasbourg, Alsace, this hop has the most acreage and largest production in France. 

We’ve barely scratched the surface of this hoppy world - these hops are only four of the many thousands that are available in the market. Next time you pick up a kölsch, lager or pilsner, keep your tastebuds alert and see if you’re able to pick up some nobility in your brew - that’s a few hundred years of history in the making! 

@vernoncelli