Monday, 16 February 2015

German brewing in the 1970’s - cooling

We’re gradually getting through this article. Though I’ll admit I’m already becoming distracted by other shiny things.

Cooling is a pretty dull but essential part of the brewing process. As is the removal of sludge.

“Cooling and Preparation of Wort for Fermentation
The whirlpool will separate hot break and hop sludge satisfactorily when the vessel has an adequate diameter. The ratio of height of wort in vessel to diameter should be 1:1.3-1.5. Fig. 1 shows the different types of whirlpools, presently found in German breweries. The classical type is widely distributed but it needs a lot of water to remove the sludge. A sludge-cup is frequently incorporated in order to allow sludge removal with a smaller amount of water. In order to shorten the rotation time in the whirlpool and so prevent an increase in the colour of the hot wort, some vessels contain a removing lube. With this device the amount of water needed to remove the sludge is low and has advantages when the sludge is added back to the lauter tun or mash filter.”
Journal of the Institute of Brewing, Volume 83, Issue 1, March-April 1977, page 75.

Sludge removal probably wasn’t such an issue when breweries still had the classic shallow open coolers. Precipitating out sludge was one of their main functions, along with cooling, obviously. Adding sludge back to a subsequent mash doesn’t sound a great idea. Surely all that gunk is exactly what you don’t want in your wort. Still, I guess it’s one step up from re-using ullage.

“Most breweries use whirlpool sludge for the next brew and add it to the finished mash in the mash copper, to the mash tun, or to the lauter tun after running-off the first wort. The smaller the amount of water needed to transport the sludge the smaller the danger of cooling the mash. Only a few breweries are of the opinion that re-use of the sludge diminishes the quality of the beer and so reject it although re-use saves at least 5% of the added a-acids and increases brewhouse yield.”
Journal of the Institute of Brewing, Volume 83, Issue 1, March-April 1977, page 75.

Desperately trying to use every bit of wort I thought was typical of British brewers because of the tax system. Back in the days when there was a fixed 6% wastage assumed by the taxman. If your real wastage was lower, then you got some untaxed beer. The German tax system didn’t work that way so I’m not sure why breweries would be so keen on re-using dodgy wort.

Conical fermenters. I must admit that I feel uneasy about them. In particular, really big ones. Though I have mellowed in my attitude. If only because pretty much everyone uses them, especially in North America.

“I will now discuss removal of cold break from the cooled wort in the context of the use of cylindro-conical fermentation vessels and the possibility of simplifying the process by using these vessels for both fermentation and maturation of the beer. More than 50 years after its invention, the Nathan cylindro-conical fermentation vessel has led to a new epoch in fermentation technology.”
Journal of the Institute of Brewing, Volume 83, Issue 1, March-April 1977, page 75.

Which puts their invention back in the 1920’s. But what about the Pfaudler vacuum system? Isn’t that similar? It dates from the 19th century. I can see the attraction of using a conical for both fermentation and lagering. But doesn’t lagering work better with a horizontal vessel?

This technique is new to me:

“The classical cold-pitching method whereby the cold wort stands in a vessel 1.2—1.5 m deep for 20 hours after addition of yeast and is then pumped to the fermentor is now rarely used. The flotation procedure, which involves intense aeration of wort by the use of aeration tubes, so that the cold break is transported by the air bubbles to the surface of the wort has now successfully replaced the classical pitching method, with the added advantage that yeast growth is accelerated. In this method the wort must be pumped from one vessel to another to separate it from the cold break. By using kieselguhr filtration this additional draw-off can be avoided but this is expensive and many breweries now try to transfer the cold wort immediately to a cylindro-conical fermentation vessel and separate the cold break from the unaerated wort by sedimentation. This method is not widely used in West Germany so that it is not possible at present to judge its influence on the flavour quality of bottom-fermented lager beers. The economics of this procedure would be very advantageous.”
Journal of the Institute of Brewing, Volume 83, Issue 1, March-April 1977, page 76.

I assume the purpose of sitting for 20 hours was to allow cold break to settle out. I assume that’s why the vessel was so shallow. Leaving the cold break in the primary fermenter doesn’t seem like a great idea. But I guess it saves money.

Fermentation next time.


Rod said...

" But doesn’t lagering work better with a horizontal vessel?"

The main problem with horizontal maturation vessels is that they don't CIP very well.

Barm said...

Silly brewers, trying to remove the sludge from their beer. If only they had read some fashionable beer books, they would know that sludge is flavour!

Anonymous said...

They may not lend themselves to easier cleaning, but I am convinced they work much better for lagering.

Rod said...

"I am convinced they work much better for lagering"

Could you explain your reasons for saying this? Not picking a fight, just interested why you think so.

Bob said...

I'm not the OP but due to the lower hydrostatic head of classic horizontal tanks the clarification/sedimentation of particles works better in such tanks rather than in (large) CKT.

Rod said...

Bob -
I think you mean sedimentation works quicker in horizontal tanks.
That's true, but if you're lagering for 4 - 6 weeks that doesn't really matter.