Some Bio On Dr. Leopold Nathan

Dr. Nathan’s Enduring Contributions to Beer Quality

We do know, or now we know, rather more about Dr. Leopold Nathan than before. The noted English brewing scientist, Lloyd Hind, wrote the obituary for Nathan in a 1938 Institute of the Journal of Brewing.

Nathan was not Swiss, or not initially, he was German, born in Berlin 73 years earlier. Interestingly, Hind doesn’t describe his education but notes that The University of Munich conferred a doctorate on Nathan in light of his achievements. This suggests to me Nathan was self-taught, or did not have an advanced technical education before starting his career, but I can’t be sure.

Hind notes that Nathan was acclaimed both for brewing and scientific discoveries. This is another way to say he excelled in both the theory and practical side of  brewing.

Hind describes his many achievements, which included collecting and purifying CO2 derived from fermenting beer, but his key discovery was the “rapid” production of lager. I explained yesterday that this was enabled by his revolutionary, narrow, cone-tipped fermenter, in which precise temperature adjustments allowed yeast to collect in the cone and be easily removed, leaving a mostly clear beer in the column.

This system was adopted in Australia between the wars with great success and in part explains the fervid beer culture – pre-eminently a lager culture – which obtains in down under. Something similar happened in New Zealand, but interestingly, the rival system of continuous fermentation was the success story there.

archery-and-targetWhat took months to achieve earlier via a slow cold conditioning was now achieved in a couple of weeks or so. That is how most beer is made to this day including top-fermented beers although storage time will vary depending on type. Nathan’s achievements were revolutionary and this clearly was seen by Lloyd Hind in ’38 albeit it would take conservative English breweries another generation to twig to the significance of what Nathan urged.

For a modern explanation of the huge influence Nathan has had, see D.E. Briggs et al.’s discussion in Brewing: Science and Practice, here.

In an article Nathan wrote in the same journal in 1930, he makes the interesting point that bottle-conditioned English ale is essentially a form of lagering. He says both involve saturating the beer with CO2 through a slow re-fermentation and take a considerable time. The main difference, he noted, was that in the case of ale, the temperature of storage is different (warmer). He says or implies that the same problems attending long lagering afflicted bottle-conditioned beer and his fermentation system would assist to make both types of beer better.

I think Nathan was only partly right in his analogy of bottle-fermented ale to lager. He saw that in both cases yeast finally settled and the beer clarified, but he seemed unaware of the flavour differences resulting from top and bottom yeasts, or if he was aware, considered them unimportant, or comparatively so.

In the case of lager, he refers to the famous Pilsner Urquell and says it was sent out unfiltered to the country districts and was very variable in quality. He meant that airborne or other contamination could spoil the beer. Some time ago, I indicated that American lager brewers albeit without benefit of the Nathan system were shortening lagering as early as c. 1870 because beer aged 7 months or so could go tart. When well-aged lager was brought back on the ground of selling the real McCoy, the drinkers rejected it.

Nathan’s innovation was not just his fermenter, but also rendering the wort sterile before entering the vessel, and he insisted on pure culture yeast. Indeed Nathan had studied under Emil Hansen after a varied career involving distilling, wine-making, and the processing of fruit juice. And so, wort transferred into into his cone-tipped fermenter was heated to ensure absence of microflora which could damage the beer later.

This explains something that has long puzzled me. Worthington White Shield, the great English bottle-conditioned beer, for many years at least was pasteurized before bottling and re-seeded with a different yeast. I always wondered why you would pasteurize a beer intended to be unfiltered at time of serving. The reason is now evident and derives from directly from Nathan’s work.

Whether wort for lager or ale is still sterilized (pasteurized is a more accurate word) before entering Nathan fermenters I cannot say – readers might opine if they know. Maybe large breweries do it and small breweries don’t. If I am not mistaken, Sierra Nevada Pale Ale is pasteurized before bottling and re-seeded with a different yeast, but it is a fairly large operation today.

One can see Nathan’s overriding concern was consistency. It’s the same kind of reasoning which led to Guinness abandoning natural conditioning of beer, whether in cask or (finally) bottle.

Was quality affected by all these changes? Chopping 4-6 month aging to a few weeks or less; pasteurizing the wort before fermenting; re-seeding it with another yeast; collecting and re-introducing to the beer an air-purged CO2.

It’s hard to say. The very best of that country Urquell was probably great, the very worst was probably undrinkable. Something in the middle might have been deemed rather a good thing if the taste was uniform and predictable. There is discussion in the 1930 article of jungbuket – the green and sulphury tastes of new lager from light-coloured malt. However, Nathan had an answer: injecting purified CO2 into the beer would “wash out” the green tastes – or so it was claimed.

Much blonde lager today has a sulphury note, but people accept it as part of the lager palate. Maybe when the Schaefers in New York brought back 7-month-beer after a period of much shorter storage, the jungbuket  (young bouquet) all leached out, particularly in a time when beer was stored in wood vessels (the porosity factor). But if the beer was half-sour, a palate devoid of burnt match smell was cold comfort, um literally.

As always, these things are a trade-off. Small-scale plants can avoid these processes on the basis their stocks are sold and consumed quickly. The odd time a craft drinker gets a bad brew, he accepts it as part of the game. In the earlier days of craft brewing, bad beer was not uncommon though. Decades later, my perception is overall quality has much improved. People have learned to do things better, and brewing technology and process control in particular at a smaller scale have improved considerably.

The logic of taking some risk is quite inapplicable to a mass-marketed brand which must remain the same every time no matter the conditions of storage and service. It is very rare to encounter a (technically) deficient brew from large brewhouses. In sampling beer since before the craft era, I’ve almost never encountered it. If the beer is obviously “off” it is due to over-age or mishandling at some level of distribution. Today with more rapid transit and increased consciousness of beer quality, this almost never happens.

Note re draft: image was sourced here and is believed in public domain. All copyright which may reside therein belongs solely to the owner or authorized licensee. Used for educational and historical purposes. All feedback welcomed.





5 thoughts on “Some Bio On Dr. Leopold Nathan”

  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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