The brewing process

Brewing beer toan 18th-century recipe  Objectives
The brewing process
Science happening in Bokrijk
Science is not always dry as dust
The “Paenhuys van Diepenbeek”
Scientific analysis of a historic brewing process (dating from 1750)

How things were in a ‘small’ home brewery remains a mystery to many. What we do know, however, is that the brewing process involved hard manual labour. Brewing was a genuine craft, passed down by tradition.

So brewing beer the old-fashioned way is hardly child’s play. For example, the different tanks (capacity 3 000 litres) take a minimum volume of 1 500 litres. This is shovelled over, stirred, filtered and pumped by hand. Then they set to work with mash-staffs weighing several kilos each. Perhaps this “hard labour” is the reason why the experiment was not attempted earlier. A team of 17 was finally recruited for the job in Bokrijk.

To keep a close track of the various stages of the brewing process, the brewery hands from Antwerp University spent the night in the historic village. After all, the process would take a good 72 hours start to finish. The complete process was carried out step by step: from malting and filtering through to hopping. Visitors could observe the brewing activities. So researchers from Antwerp University and ‘anorak’ home brewers could watch over the historic brewing process by day and by night.

The timetable below sets out the different phases of the brewing process. The most aromatic moment is the addition of the hops, around 16:00 hrs.

After much sweat and hard work, a fermentation is finally started in the “kuip”. A frothy layer of top yeast forms on the young beer. The beer now contains a variety of micro-organisms, each gracing the beer with its own particular taste and scent.
1 000 litres of beer will be run off into wooden barrels, 300 litres will be sent for analysis to Antwerp University. The beer will be tested in the university laboratory after a succession of fermenting and maturing periods.



That craft brewing is “no small beer” is illustrated by the following brewing moments:

4 May

07.00h: Fill and fire wort boiler to 80°C 09.00h: Prepare mash of crushed malt flour and lukewarm water.
Malt flour = grain (usually barley) steeped in water, left to germinate in the cellar, then allowed to dry out in the loft. 12.00h: Run sweetened mash from mash tun to filter vat. 13.00h: Filter mash and transfer wort extract to brewing copper. 15.00h: Boil wort to obtain a sterile liquid. 16.00h: Add hops, keep wort mixture on the boil for 6 hours. Hops give beer its typical bitter taste and improve its storage life and clarity. 22.00h Second hopping for that nice ‘beery’ flavour.
Extinguish fire, allow hopped wort mixture to cool in copper. 24.00h Pump wort over to cooling tank.

5 May

10.00h: Filter wort mixture.
Add yeast.
Allow wort to ferment 48 to 72 hours; clarify beer.

Finishing, 6, 7 and 8 May

  • Flocculation (formation of a thick layer of foam on the wort).
  • The sinks after approximately 72 hours.
  • The beer is run off into barrels and allowed to mature.



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