Monday, 22 December 2014

German brewing in 1966 – water

I bet you thought I’d forgotten about this series, based on an article by Narziss in the Journal of the Institute of Brewing. And you’d be perfectly right. I had.

I blame all the travelling I’ve been doing. I only remembered when pulling new material into “Decoction!”. The series came to an abrupt end with a promise of details of brewhouse operations.  Looking through past posts I realised that it wasn’t the only unfinished series. I’ll be aiming to fix that over the next month.

The title of the article section refers to the brewhouse, but it kicks off with a discussion of water. Surely that belongs to ingredients rather than brewhouse operations?

Brewhouse and Brewhouse Work
Liquor preparation.—The various types of beer require different liquors. Pilsener beers require a very soft water, and dark beers a medium hard to hard carbonate water. In between these two there are uncountable different types of water, dependent partially upon availability and partially on the working habits of the individual breweries.

Frequently, excessively hard waters are treated. In the case of some magnesium hardness, saturated calcium water is used, Recently, ion exchangers have been used employing a weak acid cation exchanger which removes part of calcium and magnesium hardness.”
Journal of the Institute of Brewing, Volume 72, Issue 1, January-February 1966, page 18.

That Pilsen has very soft water is well known.  And Munich, originally famous for its Dark Lagers, has water high in carbonates. No surprises there.

Here’s a British take on different brewing waters:

"Historically, different regions became famous for particular types of beer and in part these beer types were defined by the waters available for brewing (Table 3.1). Thus Pilsen, famous for very pale and delicate lagers has, like Melbourne, very soft water. Burton-on-Trent, with its extremely hard water, rich in calcium sulphate, is famous for its pale ales while Munich is well-known for its dark lagers, and Dublin (which has similar soft water) for its stouts."
"Brewing: science and practice", by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens, 2004, page 53.

And here’s the table that goes with it:

Analyses of some waters from famous brewing centres, (expressed as mg/l).
Parameter Pilsen Burton-on-Trent München (Munich) Dortmund London Wien (Vienna) Melbourne
Total dry solids  51 -  1226 536 273 984 320 984 25
Calcium (Ca2+)  7.1 352 268 109 80 237 90 163 1.3
Magnesium (Mg2+)  3.4 24 62 21 19 26 4 68 0.8
Bicarbonate (HCO3-)  14 320 -  171 -  174 -  243 -
Carbonate (CO32-)  -  -  141 -  164 -  123 -  3.6
Sulphate (SO42-)  4.8 820 638 7.9 5 318 58 216 0.9
Nitrate (NO3-)  tr.  18 31 53 3 46 3 tr.  0.2
Chloride (Cl-)  5 16 36 36 1 53 18 39 6.5
Sodium (Na+)  -  -  30 -  1 -  24 -  4.5
tr. ˆ Traces.
- ˆ Not given.
"Brewing: science and practice", by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens, 2004, page 56.

I’m amazed that Melbourne water manages to be a good bit softer than that of Pilsen. No wonder Victoria Bitter tastes so damn good.

Back to Narziss and water treatment:

“Water which has only limited amounts of non-carbonate hardness can be extensively softened. The carbonic acid freed must be removed by rinsing and subsequent addition of calcium. By varying the intensity of the rinsing, and introducing greater or lesser quantities of calcium-rich water, it is possible to achieve the desired hardness. By addition of slaked lime, pure calcium hardness is introduced into the water. For lightly hopped beers one desires a minimum of residual carbonate hardness of 3-5° otherwise it is feared that the beers may taste rather empty and characterless. For the building of new plants the use of weak acid exchangers is preferred, despite the increase in capital outlay and running costs. The exchange units are smaller and lighter and servicing is simpler, in spite of the need for special measures to de-activate the acidic regeneration waste water.”
Journal of the Institute of Brewing, Volume 72, Issue 1, January-February 1966, page 18.

Not sure I understand how adding calcium softens water. Surely it would harden it? And what the hell is a weak acid exchanger? Never heard of that before.

Now handling more difficult hardness:

“For waters with heavy non-carbonate hardness the so-called strong acid exchange unit is usually chosen. In this case all cations are exchanged, resulting in a water with free mineral acids. Neutralization is with lime water, and as a result the prepared liquor contains only the calcium salts of mineral acids. On the other hand, if nitrates are present in greater quantities than 40 mg. per litre in the brewing liquor then objections from the health authorities can be expected. In this case it is usual for the non-carbonate hardness to be removed by means of anion exchangers, or with water of low chloride content, by means of a chloride exchanger, which will transform the salts of the other mineral acids into chlorides. In practice, it is found necessary to improve the de-salted waters by means of an active carbon filter, in order to give greater plant security. Beers brewed from largely soft liquors are finer but also less full bodied. These characteristics can be compensated by a slight increase in hop dosage and also by the use of malts kilned off at high temperatures. Treatment with up to 15 g. per hl. of gypsum or calcium chloride is frequently used. This is equivalent to 5° of German hardness. Greater quantities are not used, as the effect on beer flavour may be detrimental.
Journal of the Institute of Brewing, Volume 72, Issue 1, January-February 1966, page 18.

I think I understand a few bits of that.

The stuff about very soft water intrigues me, and a perceived lack of body. Particular with regard to Pilsner Urquell. The extra hop dosage I can see there, but I’m sure it doesn’t use malt kilned at a higher temperature.

Adding gypsum is what’s called Burtonisation in Britain, though 15 g. per hl. is quite a small amount. Before WW II the water treatment for Barclay Perkins Pale Ales included the addition of 3.25 oz. of gypsum per barrel – the equivalent of 57 g. per hl.*

I’ll let Briggs explain why nitrates are bad:

"Nitrate levels, which vary widely, are a cause of concern as water sources are increasingly contaminated by nitrate from leached agricultural fertilizers. The fear is that during the preparation of the beer or in the consumer the nitrate may be reduced to nitrite (also limited, Table 3.2) and this, in turn, may give rise to carcinogens."
"Brewing: science and practice", by Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens, 2004, page 54.

Doesn’t sound very nice, does it?

Next time we really will get to actual brewing.

* Barclay Perkins brewing record held at the London Metropolitan Archives, document number ACC/2305/01/612.


marquis said...

Calcium bicarbonate (Ca(HCO3)2)is soluble in water , calcium carbonate (CaCO3) is not.
Judicious additions of slaked lime (calcium hydroxide,Ca(OH)2) converts this bicarbonate into carbonate at the same time being itself converted into carbonate. So it all drops to the bottom.
Ca(HCO3)2 + Ca(OH)2 → 2CaCO3 + 2H2O

Dan Klingman said...

I believe the weak acid exchanger is explained in contrast to the strong acid exchanger in the next paragraph. The weak acid exchange won't strip all the cations out of the water, leaving some residual hardness. I know strong acid exchangers can use hydrochloric acid for regeneration and thus requires neutralizing the effluent before disposal.