Saturday, 4 March 2017

The advantages and disadvantages of top-fermentaion

More from "Die Fabrikation obergäriger Biere in Praxis und Theorie". This time, a quick review of the good and bad points of toop-fermentation:

First the good:

"THE ADVANTAGES OF a top-fermenting brewery are:
1. Small amount of capital, because every brewery (even with a tun and kettle) can produce top-fermented beers. - Most top-fermenting breweries are of a modest size.
2. No Ice Machine - except in hot countries - is needed.
3. Beer can be shipped immediately after the end of primary fermentation and thus delivered earlier to the customer, meaning little space and few barrels are required.
4. A larger variety of beers can be produced and therefore every taste can be catered for.
5. Top-fermented beer is fresher and more digestible.
6. It can also be conserved for a long time and its quality will only improve through the process.

Top-fermented beers are produced not only in Germany, but also in almost all countries; For example, in England, Belgium, France almost 90-95% of all beers are top-fermented, in Holland 68%, etc."
"Die Fabrikation obergäriger Biere in Praxis und Theorie" by Braumeister Grenell", 1907, page 7. (My translation.)
I can remember reading how some of the first microbreweries in the USA initially wanted to bottom-ferment but changed their minds when they realised how expensive the equipment was. There's more of it and it's more complicated.

In Britain, breweries didn't usually ship their beer immediately after primary. Even Mild Ale would be in the brewery for 7-10 days. Stronger beers were stored for much longer, sometimes years.

The percentage of topfermenting beerr for Holland looks too high. The big Lager breweries - Heineken, Amstel, Oranjeboom - were well-established by 1900 and brewing on a far larger scale than the older top-fermenting breweries.

Here's the downside:

"DISADVANTAGES:
1. The fermentation is more difficult to control,
2. The beer is more easily infected, especially in the summer in breweries which do not have cool basements or water, do not use the best raw materials and usually only bother with superficial cleanliness.
3. Because, unlike bottom-fermenting beer, which usually clears itself by itself, clarification has to take place by artificial means.
4. As the yeast needs to be changed more frequently, especially when using adjuncts, it is difficult to maintain a consistent taste in the beers."
"Die Fabrikation obergäriger Biere in Praxis und Theorie" by Braumeister Grenell", 1907, pages 7-8. (My translation.)

It's pretty obvious that bottom-ermenting beer, which was kept relatively cool throughout the brewing process, wouldn;'t be as likely to get infected. And the long coool lagering let the yeast settle out naturally. Though English Stock Ales, which were stored a long time, though not as at cool a temperature as bottome-fermenting beer, also cleared spontaneously.

What exactly does he mean by changing yeast? Getting yeast from a completely fresh source? I can understand how that would change the charcter of a beer. Not sure why using adjuncts would require a more frequent change of yeast.

With six points in its favour and only four against, it looks like top-fermentation is tops.

3 comments:

Anonymous said...

Regarding changing yeast due to adjuncts: You'll read warnings in home brewing circles how digesting sugar, corn, etc. will "stress" yeast -- or sometimes it is said to cause it to mutate or go through a selection process -- that makes it a poor choice for repeated use.

Of course, there's a lot of folklore in home brewing that results from poor testing, bad theory, or weak anecdotal evidence, so I can't say whether this has any basis in reality. You've given a lot of examples of British brewers who regularly harvested their yeast from beer made with maize and sugar, so I don't know how valid this would be.

Matt Paonessa said...

There were tons of studies done in the late 80's and early 90's regarding the effects of adjuncts on yeast, mostly corn syrup. A lot of these studies seem to suggest that the use of high glucose adjuncts alters the way yeast uptakes glucose, even repressing glucose uptake for more complex sugars. The result of which was inhibited growth and fermentation as well as increased off-flavor production.

I'd have to look up the studies but I'm sure they're referenced in JIB around that time.

Ron Pattinson said...

Matt,

thanks for passing that on. I keep realising I actually know fuck all about brewing science. If I could go back forty years, I'd study biochemistry.