Danish brewing in 1960 - fermentation

Here, as promised, is more about Danish brewing in 1960. We're now as far as fermentation:

"Fermentation.— The essential feature of a lager attenuation is that sufficient residual extract is left to supply the requirements of the secondary fermentation in the lager tank; three methods of achieving this were used. With a single fairly flocculent yeast the primary attenuation was checked about 4° above the limit by cooling, thus giving a day or two less in the fermenting vessel; a typical example was an 8-day fermentation at 48-50° F. Again with a single yeast, the primary fermentation was completed and the necessary residual extract then added as krausening in the lager tank. The third method involved using two strains, powdery and flocculent, which were kept separate in the fermenting vessels, where they attenuated to different levels and were then mixed in the lager tank; the residual extract left by the flocculent yeast was sufficient for the secondary fermentation. A well-balanced pair of mutually flocculating yeasts was required for this process, but it was possible to standardize fermentation time without detriment to the secondary fermentation; this method was found in use both in a large brewery with its own propagating apparatus and in a smaller concern which relied on a commercial supply of yeast."
Journal of the Institute of Brewing, Volume 66, 1960, page 497.

Now there's something I'd never really considered: the need for extract during the lagering process. It makes sense - how else would the carbonate itself in the tank if there were no fermentation activity occurring. Much like bottle- or cask-conditioning, there are two basic methods of achieving this: stopping primary fermentation at the right point or fermenting all the way out then adding more fermentable material. The latter is safer, as you've more control. When I homebrewed, I never dared rely on having just the right amount of sugar left in the wort. I always primed bottles with sugar.

I was surprised when I compared Barclay Perkins methods with those outlined in the article, that the Danes were fermenting warmer and for a shorter time. Barclay Perkins pitched at 45º and let the temperature rise to a maximum of 49.5º F. Export and Sparkling beer took around two weeks in primary, Harp Lager 8 days.

Barclay Perkins Lager in 1962
Beer	Style	OG	FG	ABV	App. Attenuation	lbs hops/ qtr	hops oz/brl	boil time (hours)	Pitch temp	max. fermentation temp	length of fermentation (days)
Export	Export	1045.5	1007.7	5.00	83.08%	4.51	11.84	2	45.5º	49.5º	14
Harp Lager	Lager	1035.1	1008.6	3.51	75.50%	3.93	8.40	2	45º	47º	8
Sparkling Beer	Lager	1045.5	1010.0	4.70	78.02%	4.49	12.38	2	45º	49º	15
Source:
Barclay Perkins brewing record held at the London Metropolitan Archives, document number ACC/2305/08/276.

 

Barclay Perkins is a good brewery to be using for comparison. Not just because they had a specialist Lager brewhouse. When it opened in the 1920's the first head brewer was a Dane.

The method using two yeast strains seems very fiddly. Not sure I'd want to give it a try. Not when kräusening is so much simpler. Here's something about the primary fermentation vessels:

"The fermenting cellar was usually at 40-45° F. and contained open vessels of aluminium, ebon, enamelled iron or stainless steel, filling being from the bottom through a single filling and racking cock; an armoured rubber hose was often used to connect the vessel to the wort main system, which was usually of copper. Yeast was either injected into the filling main near the vessel or pumped in from the top during collection.
Journal of the Institute of Brewing, Volume 66, 1960, page 497.

I'm surprised that they still had open fermenters this late. Though in Franconia that's still the norm, at least among the smaller and medium-sized breweries.

"Both large Copenhagen breweries have recently built multi-storey fermenting blocks with totally enclosed vessels in stainless steel, insulated with 15-cm. layers of cork and mounted in concrete; the exterior is air conditioned to avoid condensation and heat variance in the F.V. Attemperation was by direct ammonia expansion into a single 4-in. pipe running round the vessel just below the beer line. By varying the boiling pressure of the ammonia the minimum temperature difference could be attained between attemperator and beer. Carbon dioxide was collected from these vessels."
Journal of the Institute of Brewing, Volume 66, 1960, page 497.

He means Carslberg and Tuborg by "Both large Copenhagen breweries". And I see they had closed fermenters. What do they have today? Well nothing because both breweries have closed. Wherever Carlsberg and Tuborg are brewed now, I'm sure it's in conical fermenters.

That's quite different from attemperators in British breweries. Those were a network of small diameter pipes. I would try to describe it in more detail, but It's easier to just show you a photo:

The CO2 being collected was presumably used to carbonate beer. Or soft drinks.

Finally something on yeast:

"One brewery was still using the original Hansen propagators the prototype of which was designed in 1883. Yeast was removed for further build-up about once a week, and the inherent soundness of the method was apparent from the fact that over 300 samples of pitching yeast could usually be obtained from the initial pure culture before deterioration took place.

Yeast washing was widely practised, a modern variation being to sieve the yeast direct from the floor of the fermenting vessel after racking, using a vibrating mesh screen to retain the scum and allow the cleansed yeast to pass through. Smaller breweries re-used the yeast about 12 times, but the larger concerns had more rigorous infection limits; they were able to detect the presence of one cell of Pediococcus in 0-5 g. of pressed yeast and re-pitched only about 6 times. It was interesting to note that Pediococcus was the infecting organism most feared by Continental brewers; lactic rods were rarely encountered."
Journal of the Institute of Brewing, Volume 66, 1960, page 497.

That's impressive still having a Hansen-style yeast propagator in use almost a century after it was designed. Though there are other bits of kit that have hung around for a long time. A Steel's masher is a good example. That was invented in 1853 and is still in use at many British breweries.

The implication is that British brewers most feared lactobacillus. I wonder why it wasn't common in Danish breweries?

Next time the real fun starts when we get to lagering.