Leopold Nathan – Unsung Hero of Modern Brewing

Over 100 years, many changes have occurred in beer and brewing. Two great innovations, with their roots in the early 1900s, have not changed. One is the development of pure yeast culture, which I discussed recently.

Its father is the Danish chemist Dr. Emil Hansen. He developed a reliable method to isolate a single strain of yeast from the mixed types that had evolved empirically in breweries and distilleries. This assisted production of beer with better control in every phase of the fermentation process and with a predictable, acceptable flavour.


The other great innovation, rarely mentioned in consumer brewing literature, was the invention of closed fermentation by Dr. Leopold Nathan, a Swiss chemist. He designed the cylindrical fermenter with the conical base, equipment seen in any scale of modern brewing, from brewpub to mega-plant.

He patented the system in the U.S. before WW I and slowly it was adopted on the Continent and finally in the English-speaking world. Australia was a notable cradle for the application of the Nathan Fermentation System, via Peter Hay who founded the Richmond Brewery. (His Wikipedia entry is very informative). Early British experiments with the system, initially felt suitable only for lager production, occurred in the interwar years.

After World War II, British breweries started to adopt the system in earnest, as explained by D.R. Maule of Whitbread R&D 31 years ago in this absorbing article from the Journal of the Institute of Brewing, “A Century of Fermenter Design”.

Maule’s first page is a great snapshot of where British beer fermentation started from. A multiplicity of systems was in use at the end of the 1800s, evolved empirically and often regionally. There was Yorkshire stone square, skimming systems, dropping systems, Burton Unions (linked open casks to vent excess  yeast), etc. Today, craft brewing almost exclusively uses Nathan closed fermentation. Some small brewers still use open fermentation, a few small German brewers do, but generally closed systems have taken over, even in traditional Belgian brewing.

Continuous fermentation is the other main modern method, a complex system of linked tanks which operate for many months until shut for cleaning and maintenance. This method makes them suitable for breweries producing one beer or one main brand, e.g., Guinness. The Nathan cylindro-conical system is much more prevalent.

Nathan’s invention permitted lager (initially) to be fermented and conditioned in a couple of weeks or less vs. three or four months under the older system. The fact of closed fermentation meant the beer was beyond the predation of airborne organisms. CO2 was not lost to the atmosphere as in open tanks, but could be vented in a controlled way, “washed” of its green flavours, and re-introduced to the beer. The use of temperature with maximum control including cold crashing, which the enclosed environment favoured, permitted clarification months ahead of the usual schedule.

Maule explained that the system gained traction in the U.K. particularly when cleaning-in-place was perfected for Nathan fermentation.

Nathan’s basic design, as shown in the reproduction in Maule’s article, continues virtually unchanged today. One new element is the unitank variation, where the beer fully conditions in the fermenter vs. use of a separate brite tank as it’s called. Unitanks are often useful for brewpubs, but breweries which filter the beer generally use the separate brite tank, also for more storage capacity and to free up fermenter capacity.

Who was Dr. Leopold Nathan? I know very little, online searches came up empty. He was a Swiss national, active from about 1900 into the 1930s, but after that, a blank.

He is a hero of modern brewing, attested by the longevity and reach of his system – both ale/porter and lager, at any scale of production.

To the names Pasteur, Hansen, Fritz Maytag, Ken Grossman, Jim Koch, Jack McAuliffe, CAMRA, Michael Jackson, we must add that of Leopold Nathan as an avatar of modern brewing culture.

The image above was sourced from the site of this Chinese food processing equipment manufacturer. All intellectual property therein or thereto belongs to the lawful owner or authorized users. Believed available for educational and cultural purposes. All feedback welcomed.




2 thoughts on “Leopold Nathan – Unsung Hero of Modern Brewing

  1. I’ve also discovered that he was born on July 30, 1864, in Württemberg, according to a document I found online entitled “Aus Meinem Leben” (or “From My Life”) about Nathan, but it’s in German. I’ll be in Belgium next week, with a few Germans, so I’ll see if I can ask one of them to read it over for me and possibly translate at least some of it. At least now I have some time before a birthday post can be done. Thanks for bringing him to my attention. Cheers, J

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