Tuesday, 24 February 2015

Cask beer in the 1950’s – secondary fermentation

I’m continuing my look at the handling of cask beer in the 1950’s. There are a few surprises.

Secondary fermentation is extremely important for cask beer. It’s where it gets its carbonation. But appears much more complicated than I imagined.

Secondary Fermentations
There are two kinds of secondary fermentation. One is a healthy one, due to me breaking down of the sugars passed on from the primary fermentation by healthy yeast. The other is the result of wild yeast. If the beer was not encouraged to develop a certain amount of movement in the cask, it would provide a very dead and insipid drink. It is the condition, mostly derived from fermentation while in the cask, which imparts that sting and sharpness on the palate. Together with a satisfactory flavour, these points are those most appreciated in beer. Even with running ales some attempt should be made to encourage a movement, by priming with a solution consisting mainly of fermentable sugars. Some malto-dextrin, is, however, necessary to carry on the development of condition. The casks should be rolled as frequently as possible before being sent out, provided that violent condition is not set up. Once beer, of whatever gravity, is saturated with its naturally developed gases, it can stand variations of temperature with comparative impunity. Here again, as in many instances with beer, the seasons have to be carefully considered. It would be dangerous to send a cask out in the broiling sun of summer if it was already charged with gas to the limit of its pressure resistance. Its head would probably be blown out during transit, or the staves would bulge and crack, thus losing much beer. Great difficulty would, of course, be experienced in getting the beer quiet and in saleable condition, when it reached the public-house cellar. On the other hand, if the beer has attained its full condition, it could, during the winter, be placed in the open and exposed to many degrees of frost without harm, provided that the temperature of the cellar in which it is subsequently placed is higher than that of the temperature prevailing outside. The temperature should not, however, be too unreasonably high.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, pages 243 - 244.

This is an interesting redefinition of secondary fermentation. Fifty years earlier, by definition secondary fermentation wasn’t the result of normal yeast. It was the result of Brettanomyces, which you can argue is wild. Back then what’s been described would have been called an extended primary fermentation. Of course, Brettanomyces is very different from just any old yeast or bacteria.

Do you really need malto-dextrin for conditioning. Is the idea that it would be consumed slowly by the yeast rather than in a full-blast fermentation?

Does carbonated beer really handle temperature changes better?I’ve no idea. Leaving the beer outside in the winter reminds me of the piles of Bass Pale Ale stacked up outside the brewery in the 19th century. Was that being protected by carbonation? Or was it just as touch as old boots?

Now some good stuff about Stock Ales:

“Stock ales are brewed with the object of a certain amount of malto-dextrin being carried forward into the casks. The malto-dextrin has to be broken down gradually by the few remaining healthy yeast cells which should also be present. It is therefore necessary to encourage a slow fermentation in order to achieve the object. Sometimes the fermentation will develop spontaneously. As soon as it is noted a porous peg should be inserted in the cask in order to ease the pressure of gas. Immediately the pressure has slackened a hard peg must be substituted or the beer may flatten to a degree from which it might never recover. Generally, one fret in the brewery cellar is sufficient for ordinary beer, but for extra strong ales which are stored for many months, two or even three frets in the cask may be necessary. If any difficulty is experienced in bringing them into action, a vigorous rolling coupled with a slight rise in cellar temperature, and if necessary the addition of a small amount of priming, will generally have the desired effect. The use of priming at this stage is not advised with confidence, since it might well result in rousing wild yeast to action, with troublesome turbidity as a result. It cannot be too strongly emphasized that the correct manipulation of both hard and porous pegs has a very great effect on all cask fermentations.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, page 244.

So I was right about the malto-dextrin. It was providing slow food for the yeast. (You can tell I hadn’t properly read this before I started writing.)

By ‘fret’ he means an active fermentation. Interesting that a beer stored for longer could have several. And how much active attention the beer demanded, like beer in a pub cellar. All that fiddling with spiles sounds labour-intensive.

Here’s another subtle dig at the cellarmanship of publicans:

“One other point is important in connection with secondary fermentations. Brewers should always endeavour to arrange them to take place in a brewery or store cellar, rather than in that of a public house. Very few licensees know how to manage a cask fermentation. Some are even alarmed at it, and at once imagine that the beer is defective. We have heard of many cases when beer fermenting in casks has been returned to the brewery without even waiting to see the result of the cask movement.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, page 244.

I’m amazed a brewery would even consider letting maturation take place in the pub. Though I’m surprised Stock Ale is even mentioned. I thought it was pretty much dead by then, with the exception of a few survivors like Russian Stout.

Priming next time.


Tandleman said...

"I’m amazed a brewery would even consider letting maturation take place in the pub."

No room in most breweries to do it there, though some these days do hold it in the brewery where possible to stop green beer being served as soon as it drops bright.

Most beers are primed for secondary in the brewery. Some with unfermented wort, some with bespoke commercial primings, some with white sugar etc.

Some are conditioned in tanks then casked with sufficient live yeast to be seen as real ale. It varies enormously as I imagine it always has done.

As for these strange practices suggested, "Once beer, of whatever gravity, is saturated with its naturally developed gases, it can stand variations of temperature with comparative impunity" Well, yes. Until you open it. A beer will start to lose condition as soon as it is vented.

Gary Gillman said...

I always thought that malto-dextrin cannot be broken down by ordinary or "healthy" yeast. The answer may be that in his era, the strains used by brewers were multiform, with some wild influence resulting from the the local (non-sterile) environment. In our era of pure cultures of one strain (generally), this is why brett is dosed into e.g. Orval.


Bitter_Bob said...

It was my understanding that Maltodextrin is nonfermentable by yeast. As a homebrewer, I've used it to add mouthfeel to a beer that attenuates lower than desired.

Even according to wiki- it is unfermentable. http://en.wikipedia.org/wiki/Maltodextrin

From the reading it seemed that MaltoDext was added in addition to the sugar for this same reason-
"...by priming with a solution consisting mainly of fermentable sugars. Some malto-dextrin, is, however, necessary to carry on the development of condition."

StringersBeer said...

Just the other day a (new) customer asked us "is it tank conditioned?" "No", we said. "Oh", they said, "How long will it take?" We explained that we didn't send beer out until it was, you know, ready, after spending time in our (cask) conditioning room. And we wouldn't typically prime. But you're right @Tanders, there's some brewers don't consider that their job. Job's half done, if you ask me, but they seem to charge full price.

Joe Walts said...

My take on the comment about carbonated beer handling temperature swings better is that the yeast need to operate in a fairly narrow temperature range to make the CO2 in the first place. Once the CO2 is made, the effects of temperature on fermentation won't matter.

Oblivious said...

Brewing yeast general have issue with anything above Maltotriose, which is a maltodextrin . It just depends on how hydrolysed the maltodextrin is, a lot of di and tri would make it fermentable able, polymers would not