Monday, 15 November 2010

Natural vs. force carbonation

The Journal of the Institute of Brewers. What handy books they are. I'm delighted to have a few in my digital library.

Given all the enthusiasm for keg at the moment, it's time to hear the views of brewing experts on the topic of forced carbonation. Experts from about 100 tears ago. Long dead all of them, so no chance of them arguing back.

Whitbread Family Ale: you remember me mentioning that recently. That was one of the bottled Light Bitters discussed in this article.It's a type of beer which, in the form of Light Ale, live on today.

"During the last decade, a steadily increasing demand for light gravity, brilliant, sparkling beer in bottle has sprung up, and various methods of treating beer, both in cask and bottle, have been practised to meet such a demand. We propose to bring before you the details of a system of bottling which has been most successful in practice, and which we hold to be superior to all other systems at present in use.

. . . . . . . .

The ordinary process of bottling is so well known to every one here, that it is hardly necessary for us to state that all beer intended for bottling should be made from first-class materials, should be preferably brewed during the winter months, be well matured in cask, and only bottled when brilliant, and after the ordinary secondary cask-fermentation has taken place.

There can be no doubt but that such beers, brewed and bottled under most favourable conditions, present to the palate a peculiar pungent flavour and an invigorating freshness which is greatly esteemed amongst connoisseurs; but there is one drawback to all such beer, they must inevitably be accompanied by a deposit, and which in many bottled beers is more or less heavy. It was to obviate this effect that the carbonating system was first introduced, and although such a system was much decried at first, and described by one writer as " an aerated draught beer in bottle," the bulk of the carbonic acid gas being merely dissolved in the liquid, which on reducing the pressure
immediately came out of solution; and the writer goes on to explain why a glass of "natural" bottled beer will, as a rule, retain its gas and remain drinkable when exposed to the air for a much longer time than a glass of carbonated beer.

In all probability there was a good deal of truth in these remarks when the carbonating system was first introduced and for some years afterwards; but we think when you have tasted the various samples of beer which are before you, bottled on the carbonating system that we are now about to explain in detail, you will find that it is now possible to produce a carbonated beer in bottle in every respect equal to that produced on the old plan.

In order to successfully produce a first-class carbonated beer in bottle several points have to be observed. Amongst others, the beer must be specially brewed for this purpose, the object being to obtain a finished beer possessing as little fermentable matter as possible and a very low attenuation. The following analyses will perhaps show the differences, to a certain extent, between a carbonated beer on the system we suggest and light bitter beers bottled in the ordinary way where condition is brought about by after-fermentation in bottle.

Analyses of Bottled Beers.
Column I. Carbonated Light Bitter Beer.
Columns II and III. Two well-known brands of Non-carbonated Light Bitter Beer.

Original gravity 1044 1048.7 1045.3
Specific attenuation 1006.4 1009.8 1011.4
Absolute alcohol per cent, by weight 4.15 4.15 3.75
Proof spirit per cent, by -volume 9.1 9.1 8.2
Polarisation (200 mm.) tube 7 7.6 9
Matter fermented per cent 71.17 65.74 61.97
Maltose unfermented per cent 7.16 7.98 9.17
Dextrin unfermented per cent 11.1 10.86 13.72
Passive matter 10.57 15.42 15.14

"Journal of the Federated Institutes of Brewing, vol VIII, 1902", pages 297-299

So there you have it. The carbonation in a naturally-conditioned beer is different to that of a force-carbonated one. I'll be happy to discuss the topic, as long as you don't use the argument CO2 is CO2.


Gary Gillman said...

It's a very interesting question. One difference I've noted is that naturally-conditioned beer seems to result in smaller bubbles than artificially carbonated beers. Can it be just a question of the relative volumes of CO2 in each? Possibly, since if you pour hard to reduce the CO2 in a fizzy beer, the bubbles seem to get smaller (and the result much like real ale from the carbonation standpoint).

The main difference for me in such treatment is that real beer including bottle-conditioned beer has a particular savor, which this author has noted. Even filtered, unpasteurised beer, kegged afer conditioning at the brewery, doesn't taste the same. Theoretically it should. One can view a keg of such beer as a sort of advance glass or extension of it, but in practice the result is usually quite different to real ale, or so is my experience.

Probably the time factor is all important here: the longer it is off the lees the less real ale character it will retain. Temperature too plays a role. Craft keg beer is almost always served colder than real beer although why I am not quite sure.


Barm said...

"as little fermentable matter as possible and a very low attenuation"

Aren't these two qualities mutually contradictory?

Ed said...

Excellent find Ron, that'll muddy the water further!

Ron Pattinson said...

Gary, I've heard that about naturally-conditioned beer, too. And about properly lagered beer. Finer bubbles.

Wonder if there's any truth in it?

Ron Pattinson said...

Barm, I think they mean attenuation to a low OG. Otherwise, it makes no sense. And, in my posts on Whitbread bottled beers in 1872, that the FG's were low.

Chad Yakobson said...


Great topic.. I await the 100+ comments that will follow.

My first question is were all three of those beers the exact same beer brewed and taken from the exact same wort stream, primary fermented with the same yeasts under the exact same conditions with the only differences in their final carbonation technique?
As I suspect they are not then the results are not scientific and do not prove much. This would not surprise me as the article is from the early 1900's. When it comes to the UK and "proving" that their beer is "better" (a war has been brewing between Britain, Belgium and Germany for hundreds of years) they have often over look many hard facts in order to feel a certain satisfaction of superiority. Cask conditioning has been their bread and butter as well as a few other techniques. As I did study my Masters of Brewing and Distilling in Edinburgh, Scotland I too have poured through the IOB journals and had a good laugh at some of the articles that have been published, and it is also the reason in Uni they didn't not want us using brewing article much older then the 70's as they even admit its a load of ballocks compared to what has since been proven.

to be continued...

Chad Yakobson said...

The hard scientific truth is CO2 is CO2.. the topic is not over CO2 is over the technique which is used to get the final volume of CO2 into the final product. There are obvious changes between a CO2 force carbed beer and one that has a secondary fermentation from yeast. The changes in flavor come from creating a secondary fermentation in the bottle and the secondary compounds released or consumed. The flavor changes have to do with higher alcohols being formed due to growth and possible secondary esters which are synthesized or consumed. Every yeast is different, as well as every brewer is different. Some beers fare better and some worse. While a beer that is force carbonated is in no way less superior or lacking anything. In fact an easy argument can be made for why it is a superior product produce to a flavor the brewer intended to have. A brewer can easily accomplish everything he is looking for in a bottle conditioned beer while still using force carbonation. Some brewers may prefer the secondary conditioned beer saying it gives a certain quality they can't find a way to achieve without it.

Chad Yakobson said...

As for your previous article it is not true that all German beer is force carbed. The german technique is to naturally carbonate in the fermenter by capping off the tank with around 1 *P left. By doing this the beer force carbs in the tank and is continually transfered under top pressure to retain the "natural" carbonation. This is the greatest technique (In my opinion) as it leaves the beer tasting the way the brewer intended without creating various flavors from the yeast that is not controlled buy the brewer therefore a loss in control of the product at the final stage of production. Bottle conditioned beers will develop autolysis flavors and leave sediment, at the bottom of the bottle. If poured off the yeast bite changes the flavor and is often not very tasty.

As a brewer trained in the UK, brewing in the US with an in-depth knowledge of German brewing techniques as well... There is a great argument for both sides of the fence.. The obvious answer should be whatever the consumer thinks he/she prefers... as taste and interpretation is open to the drinker. If they prefer one then they are the one thats right. A brewer will have his own dogma as that is what brewing is really about to all of us, and drinkers either buy into it or not. At the end of the day the only thing that is important is the quality of the beer and the satisfaction it gives the consumer buying that product. Which ever technique is used it must satisfy the consumer and give them the greatest 10 minutes of satisfaction, while they consume that beer. If that comes from a sour/wild beer which aged for 2 years in oak barrels but was unfiltered and forced carbed to 2.6 vols to retain the flavor the brewer wanted during his/her blending then so be it. It still has all the yeasts present (doesn't get much more natural then that..) and the wild yeast and bacterias are free to carry out further slow fermentation/carbonation taking that carb level higher and giving a degree of secondary carbonation in the bottle... Now it's not so black and white as there is both techniques occurring.. But all that is important is that the that beer tastes amazing and is enjoyed to the fullest!

Chad Yakobson said...

As a final note.. I'm pretty sure that the article you have posted is actually referring to the use of Brettanomyces (while they wouldn't have yet known) as that was also a long held reason for not using single yeast strains in Britain. To quote "There can be no doubt but that such beers, brewed and bottled under most favourable conditions, present to the palate a peculiar pungent flavour and an invigorating freshness which is greatly esteemed amongst connoisseurs" this is almost the same line Clausen used when presenting research to the IOB in 1904 stating that the characteristic flavors associated with Brittish beer could not be achieved through single strains. He had isolated strains which did create the Brittish flavor. He went on to call them Brettanomyces. And with that I must agree that Brettanomyces yeasts used in secondary does produce some of the finest beers found anywhere! An Orval anyone?


Gary Gillman said...

I thought the pungent quality might have been yeast bite plus co-products (higher alcohols and others as mentioned in the comments above), but if brettanomyces did not characterize running beers, how could it get into bottle-conditioned ones i.e., at a time when they would not have filtered and re-seeded with another yeast? The only way I could see is if some wooden vat beer was blended with mild beer before bottling. But would pale ale - a classic bottle-conditioned type - have been treated like that?

I wonder if Orval, which I understand is inoculated with brett yeast for part of its conditioning, was attempting to resemble the character of a long-aged barrel beer.


Graham Wheeler said...

There is the answer then, in a nutshell. Easy enit