Friday, 26 December 2014

German brewing in 1966 – mashing

Finally, after many, many months, we’ve got to the brewhouse.  Thank you for your patience.

We kick off with a description of the mashing process:

“The brewing process.—This is identified by the mashing method. Normally a decoction method with two mashes is used and only in rare cases is the infusion system applied. Pilsener beers have a thin mash (4-6 hl. main mash per 100 kg.); the mashing temperature (56-62° C.) requires smaller part-mashes. In many cases the pale colour of the wort will be obtained when husks are not boiled with the mash. Subsequently the husks are added to the mash before lautering takes place. By these means reductions in tannin values of approximately 10-15%, and in husk bitter substances of approximately 8-10% can be achieved. Stronger beers are mashed more intensively by lowering the mashing temperatures; alternatively, larger part-mashes may be boiled for a longer period, or a concentrated mash (less than 4 hl. per 100 kg.) can be used. Dark beers are still usually prepared with the 3-decoction method, mainly in order to obtain the required flavour. As a result the brewing period is lengthened (12-15 hr.).”
Journal of the Institute of Brewing, Volume 72, Issue 1, January-February 1966, page 19.

I’ve read before about special care being taken in the mashing of Pilsener to make sure that the colour remained very pale. Keeping the husks out of the decoctions is quite extreme and presumably required some special manipulation of the grist after grinding. Obviously, you’d want the husks there at the lauter phase to help filter the wort.

You may remember from other articles that the classic Pilsener decoction method is Hoch-Kurz, where the mash in is at the relatively high temperature of 62° C. Again the idea is to prevent as much as possible any darkening of the wort.

I’m sure that infusion mashing has become much more common in the intervening years, at least amongst industrial brewers. For the simple reason that it’s cheaper and quicker than decoction mashing. For very pale beers like Pilsener it also means you don’t have to worry about any darkening of the wort during decoctions.

They were a bit obsessed with continuous fermentation in the 1960’s and 1970’s. Does anyone still practice it? I seem to remember there being some small problem with the flavour of the finished beer: it tasted crap.

“The variations between the mashing methods are probably the reason why continuous brewing methods have not been examined in greater detail. Czechoslovakian authors and a unit of the Ziemann firm, which was displayed at the Dortmund Exhibition, are, however, tackling these problems.”
Journal of the Institute of Brewing, Volume 72, Issue 1, January-February 1966, page 19.

This sounds very much like the process described as traditional decoction mashing by Griggs:

“In traditional continental European decoction mashing a thin mash (3.5-5 hl liquor/ 100 kg. grist; 3.26-4.66 imp. brl/Qr.) is made from undermodified malt that is comparatively finely ground. The thin mash is necessary to permit it to be stirred and pumped between mashing vessels. In this, and the other mashing systems to be considered, the mash conversion processes are carried out in vessels that are separate from the devices (lauter tuns or mash filters) in which the wort is separated from the residual spent grains. Because the mash is stirred and portions of it are pumped between vessels air is not entrained and the solids do not float. When portions of the mash are boiled the starch is gelatinized and becomes susceptible to enzymic attack, residual cellular structures are disrupted, proteins are denatured and precipitated, enzymes are inactivated, chemical processes are accelerated, flavour substances (not necessarily desirable) appear in the wort and the wort darkens. Unwanted substances such as pentosans and B-glucans are extracted. Boiling portions of the mash is expensive because it involves the consumption of energy. The successive temperatures, which occur in the `main, mixed mash', allow key enzymes to act at or near their optimal temperatures. In decoction mashing the grist is mashed into the mash-mixing vessel, which has a stirrer and may have heat-exchanging surfaces to allow the temperature of the contents to be increased. At intervals aliquots of the mash are withdrawn to the decoction vessel where they are heated, rapidly or slowly as the programme requires, with or without `rests' at particular temperatures, to boiling. After a period of boiling the hot material is pumped back into, and is mixed with, the main mash raising its temperature at a predetermined rate to a pre-chosen value. Before a decoction is carried out the stirrer in the mash-mixing vessel may be turned off and the mash allowed to settle. Then part of the settled `thick mash' is pumped to the decoction vessel.”
"Brewing: science and practice", by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens, 2004, page 90.

Not that Briggs specifies a slightly less thin mash than Narziss: 3.5-5 hl liquor/ 100 kg. Grist as opposed to 4-6 hl. This is much thinner than a British-style infusion mash, which is typically 1.6-3.2 hl liquor/100 kg grist*.

“With conventional brewing units one attempts to carry out the lautering as quickly and as evenly as possible, in such a manner that the time interval from one brew to another is between 3 and 4.5 hr. using a five-vessel brewhouse. Improvement in lautering by steaming of the malt before grinding, or by wet grinding, can be obtained.

The new Steinecker lautering tun uses wet grinding and works with a grist depth of 60 cm. This unit combines speedy filtration with optimum sparging conditions, and with it one can reach 7 or 8 brews per day; with steam grinding it is also possible to reach 7 brews per day, and at the same time, as a result of the improved grinding of the hardest portions of the grist, reduced mashing times can also be obtained. The extreme is provided by the half-continuous wort unit of Reiter, which reduces mash times to 1 hr. (with one decoction mash) as a result of using a very high percentage of meal in the grist. As the lautering process only requires 1 hour, including sparging, all of which is achieved by the use of a vacuum drum filter, it is possible to cast one brew every hour, provided three coppers are available. With the exception of this particular working unit, other units, such as the brewing column or the erection of vessels on one level behind a wall, still employ well-known brewing methods. Nevertheless, attempts are being made to automate parts of the brewing process: this can already be observed in the mechanization of the mash filter. In particular, the use of plastic cloth has simplified the methods.”
Journal of the Institute of Brewing, Volume 72, Issue 1, January-February 1966, page 19.

Speeding up the brewing process is another obvious way to save money. Cutting down the mashing time to just one hour seems pretty extreme. But it means a brewery could rattle through the brews. 7 or 8 a day is very good going.

Next time it’s boiling and cooling.

*"Brewing: science and practice", by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens, 2004, page 90.


Ed said...

Continuous fermentation only became established in New Zealand, where it's still used on a large scale.

Barm said...

Augustiner are known to mash husks and flour separately to get the very pale colour of their beer. This text suggests it was once a common practice.