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What’s the best fermentation system? Who hasn’t asked themselves that while soaking in the bath or bobbing along to work on the bus, some grey winters day?

You’re in luck, because Kieninger is going to tell us. Or at least give us his opinion. He worked at Weihenstephan, so he must be right, musn’t he?

“Table XII also shows the most simple and effective method for the fermentation and maturation of lager beers of high quality in the light of modern knowledge. Primary fermentation is carried out in closed vessels, so that it is possible to collect the carbon dioxide and any required temperature may be applied. After reduction of diacetyl the green beer is cooled by plate coolers to a temperature of 0°C and after remaining at this temperature for 2-3 weeks for stabilization it is carbonated and filtered. The only analytical controls required are diacetyl and carbon dioxide and the carbon dioxide content may be controlled by in-line instrumentation.”
Journal of the Institute of Brewing, Volume 83, Issue 1, March-April 1977, page 76.
Lager in just 28 days. I’m not sure he’s convinced me about that. I’m sure it’s a cost-efficient way of brewing. But what about the flavour of the beer? That doesn’t get a look in. Notice that it’s not even taken into consideration.

The best Lagers I’ve had I mostly knew were open-fermented, lagered for months rather than weeks and were naturally carbonated.

I’m going to repeat that table, because it’s a while since the last post in this series:

TABLE XII. Comparison of Fermentation and Maturation Systems.
Method Primary fermentation Transfer Lagering
Classical 7 days at 9°C Beer with 3-5% residual extract cooled to 4°C 35-50 days with temperature reducing from 3° to 0°C
Using Kräusen 7 days at 9º-10°C Beer with 2% residual extract cooled to 4°C. 10-12% Krausen with 8% residual extract added 14-28 days with temperature reducing from 4° to 0°C
Under pressure at high temperature (Champagne Wheat Beer) 3 days at 16°C or 4 days at 14°C under pressure Beer with 2% residual extract 2.0 bar pressure cooled to 0°C 7-14 days stabilization at 0°C
Modern development 7 days at 12-14°C with CO2 collection Attenuated beer carbonated and cooled to 0°C 14-21 days stabilisation at 0°C and final carbonation

This next bit is interesting, even though it slightly baffles me:

[INDENT]“Fig. 2 illustrates the relationship between the time necessary to reduce diacetyl content to a value of 0.1 mg/litre and maturation temperature. At a temperature of 30°C, 48 hours are sufficient to reduce the diacetyl content to