Inside the Dorchester Brewery (part three)

Here's another series of posts I'd forgotten to continue. I really don't know what's happening to me.

We're moving on from the mashing stage to the coppers. I'll have something to say about the equpment there later.

"We next bent our steps to the copper stage, situated in a portion of the boiler-house, where there are two large coppers, heated by steam, and from whence we had a fine view of the engines and great steam boilers. Following the process, we next proceeded to the cooling house, situated on the left side of the brewhouse, and adjoining the hop stores. It is 104 feet in length, and contains four open coolers, commanding one another, all resting on iron columns and joists of massive construction ; also two vertical refrigerators, of the most modern pattern, cooling at the rate of sixty barrels per hour. This is a very cool place, even in the summer time, as the walls are louvred on all sides, and a box louvre fixed along the centre of the roof.
"Noted Breweries of Great Britain and Ireland, vol III", by Alfred Barnard, 1890, pages 136-137.

The cooler is a stupidly simple piece of equipment. Yet it's use has come to be almost totally misunderstood. A cooler is a large, extremely shallow, square vessel. It was located high up in the building in a room with louvred windows to allow the floww of air over the wort. Its primary function was to cool wort, but it also helped clear the wort of debris. Being very shallow, anything suspended in the wort would quickly fall to the bottom, forming "cooler sludge".

If I tell you the German name of this piece of equipment, you'll probably guess what the modern misunderstanding of it is. The German word is Kühlschiff, often incorrectly translated into English as coolship. The real English word is cooler. For some reason, people havbe got it into their heads that coolers are connected with the brewing of sponrtaneously fermented beer. Some even that think they are fermentation vessels. They aren't. They're just a way of cooling wort.

Let's make this very clear: every brewery in Britain had a cooler. They didn't start disappearing until well into the 20th century. Even after the development of paraflow coolers like the Morten's refrigerator and artificial refrigeration, breweries continued to use coolers. Nothing to do with spontaneous fermentation.

Eldridge Pope's fermenting room in the 1890's.

"After cooling, next follows fermentation, which is conducted in a separate building.

There are several methods or systems of attenuation, such as the London, Burton, Yorkshire and Edinburgh systems, all of which lead to one result. At the Dorchester Brewery, that known as the skimming system, as practised in London and elsewhere, is the one adopted, or rather that has been in use since the brewery was founded.

We were charmed with the lightness and cleanliness of the tun room, its white walls and ventilating windows. This lofty room, measuring some 80 feet square, contains sixteen fermenting rounds, with a total capacity of nearly 2,000 barrels. Three of them, recently manufactured and erected by Wilson, of Frome, which hold about 160 barrels each, are of English oak, and well worthy of admiration. On the floor, between each pair of vessels, are ten shallow but capacious yeast-backs, constructed of slate, for receiving the yeast from the "fermenting rounds" which is skimmed from the top of the beer to an outlet on the side of each vessel. All the "rounds" have attemperators, either fixed or movable, for cooling the beer during the process of fermentation. Here, on this level, overlooking the tun room, is the brewer's office and laboratory, most pleasantly situated, with a bay window having a full command of the yard. Both are most completely fitted up and furnished; and the latter contains many scientific instruments, including Mr. Crouch's useful brewers' microscope. Here we found the head brewer, and his able assistant, busy testing yeast for the day's pitching. The former stated that a change of yeast has not occurred for two years, as the present sample retains its working
purity."
"Noted Breweries of Great Britain and Ireland, vol III", by Alfred Barnard, 1890, Page 137-138.

The skimming system was one of the methods of cleansing, rather than fermentation per se. Like Burton unions, the dropping system or pontos, it was basically a method of removing yeast from the wort. Whereas the latter three all required extra vessels, skimming was performed in the fermenter. Yeast was removed from the the wort by skimming it from the top, often using a parachute - a cone which  floated on the top of the surface. Yeast was pushed into it by a plank moved across the surface of the wort. In this case, it sounds like there was no parachute but something attached to the side of the fermenter. The skimmings were moved to slate yeast backs, where presumably any wort skimmed off with the yeast was recovered.

The yeast backs were arranged between the fermenting vessels in an arrangement like this:

the circles are the round fermenters, the rectangles the yeast backs.


I believe that you can also see the end of a yeast back behind the fermenter in the foreground in the illustration taken from Barnard. The hatch on the left of the fermenter is presumably connected with skimming off the yeast.

The presence of a laboratory and the use of a mircoscope to check the yeast is a sign that the Dorchester Brewery was modern and well-equipped. Microscopes first came into use in breweries in the 1870's. Whitbread bought theirs immediately after Pasteur had visited the brewery in 1871 and used a microscope to highlight problems with their yeast.

Just the vat-house to go then we'll be onto descriptions of Eldridge Pope's beers themselves.

The three systems of fermentation 1880-1914

More laugh a minute stuff from "Principles & Practice of Brewing" by Walter J. Sykes & Arthur R. Ling, published in 1907. I wonder if I still have any readers left?

It's not surprising that the more labour-intensive methods described below have disappeared. Even the most sophisticated method of cleansing, Burton unions, is pretty fiddly.




The cleansing system
Probably having its origins in domestic brewing, this was the oldest method of fermentation. Originally, trade casks, that is the casks in which the beer was sent out to customers, were used for cleansing. After about 48 hours in the fermenting tun, the process of separating out the yeast began and the wort was transferred to trade casks. A few breweries still used this old-fashioned method in the early 20th century.

By the late 1800's, it was more usual to use large casks - butts, puncheons or pontos, each holding several barrels - for cleansing. These were known as "loose pieces" because, unlike the more sophisticated Burton Union method of cleansing, the barrels were not permanently fixed to a frame, but could be removed for cleaning. Yeast was pitched at 56º to 60º F and after 36 to 40 hours, when the temperature had risen to about 70º F and the gravity reduced by half, the wort was transferred to the cleansing casks. Splitting the wort into smaller volumes helped to keep down the temperature. If the temperature in the fermenting room was 45º to 50º F, the wort in the casks could get no warmer than 70º F.

In the summer, it was possible that the wort could become too hot so, as a precaution, it was moved to the cleansing casks earlier in the fermentaion, when it was cooler. Burton Unions were fitted with attemperators, so this was not necessary.

Some beer was expelled along with the yeast and it was important to top up the cleansing casks with clear wort. If they were not keep totally full, yeast would fall back into the beer and defeat the object of the operation. In some arrangements, such as Burton unions, topping up occurred automatically. In other cases, it was performed by hand, usually at intervals of around 3 hours.

As far as I am aware, the unions at Marston in Burton are the only remaining example of this form of fermentation.


The skimming system
This began exactly the same as the cleansing method. When the skimming point was reached, the wort was left in the fermenting tun but thoroughly roused. The yeast head was skimmed off every 6 hours. Temperature was controlled by means of attemperators. These were switched on when the temperature of the wort had reached 59º F and so regulated as to allow the wort to rise 1º F every 6 hours. The flow of water through the attemperators was increased when the wort hit 65º or 66º F to stop the wort warming any more. When the fermentation was nearly finished, the the water flow in the attemperators was increased even more to cool the wort down to 60º F.

Skimming stopped when it was estimated there was just enough yeast left to throw up one more head. This was checked by moving aside the head to look at the wort. If it was black and clear, it was ready and no more skimming was needed. If it was brown and opaque, it still contained too much yeast.


The dropping system
This was a variation on the skimming system developed by William Garton. When the wort had almost reached the skimming point, it was let down from the fermenting tun to a shallow settling square. The process of "dropping" both aerated and roused the wort. Much of the sediment was left behind in the fermenting tun.

Once in the settling square, the wort was skimmed and its temperature controlled by attemperators as in the skimming system.

Fullers were using the dropping system in 1910. They usually dropped the wort after just 12 to 18 hours in the fermenting tun. This is the record of a typical fermentation:


The temperatures match pretty much exactly those given by Sykes and Ling in their description of the skimming system.

Most London breweries employed either the cleansing system or skimming system. I am unaware of any brewery that still uses the cleansing system. There is at least one brewery (Refresh for the Brakspears beers) that continues to use the dropping system.


The stone square system
This method, as its alternate name "Yorkshire square" implies, was common in the north of England. It produced beers that were full-bodied and with a high CO2 content. A special type of slow-acting yeast, which needed a great deal of rousing, was used.

A small amount of yeast, just 1 to 1.5 pounds per barrel, was pitched at a temperature of 58º to 59º F. The yeast was mixed with a little wort in the upper chamber, thoroughly roused and then let down into the main chamber through the "organ pipe". The wort was then left undisturbed for 36 hours during which time the temperature rose to 62º F. For the next 12 hours, the wort was roused every two hours. Yeast rose through the central manhole and settled in the upper chamber.

The next stage was pumping. Wort was pumped into the upper chamber and mixed with the yeast that had settled there. The valve in the organ pipe was then opened to allow the wort and yeast mixture to run back into the main chamber. This process was repeated every two hours, starting with 15 strokes of the pump. On each subsequent repetition, the number of strokes was increased by 10. The wort was kept cool by the attemperating "jacket" formed bt the double walls of the square. Pumping ceased when the wort was within 1 or 1.5º of its finishing gravity.

After pumping was over, the yeast which rose into the upper chamber was removed any four hours. Any beer which had risen with the yeast was let back down into the main chamber through the "organ pipe". When all the yeast had been removed, the temperature of the beer was gradually reduced to 60º F. The manhole was then closed and the beer left to settle for 48 hours before being racked.

Yorkshire squares are the only one of the three fermentation systems still in widespread use. Breweries using them include Sam Smith's and Tetley's.

Fermentation 1880-1914

I'm still using "Principles & Practice of Brewing" by Walter J. Sykes & Arthur R. Ling, published in 1907 as my source. There's so much goodness in that book that I've had to split fermentation into two parts. Part two will be tomorrow.

Today we'll just be looking at the basics.

In case you're wondering, I've now got 75,000 words of the book done. Which is about half way. At 10,000 words a week, with a following wind I should have the bulk of it polished off by the end of the year. Then I just need to add the stupid jokes.




Fermentation
The amount of yeast for pitching was calculated based on the volume of wort to be fermented and its gravity, stronger beers requiring more. For a wort with a gravity of 1050 - 1055º, 1.5 - 2 lbs per barrel of yeast was needed; for a wort of 1066º, 2.5 to 3.5 lbs; and for worts over 1066º 3 to 4 lbs.

In 1910, according to their brewing logs, Fullers used much smaller quantities of yeast than those just quoted:

AK 0,65 lbs yeast per barrel
Brown Stout 0,94
Porter 0,44
PA 0,67
X 0,74

The yeast used had mostly been harvested from X, though in one case "Mann's Yeast" is specified.

Yeast was either added directly to the wort or first mixed with a quantity of wort at between 65 and 75º F to form a starter. The latter method was a better way of ensuring that a vigorous fermentation started as quickly as possible.

Weaker beers - those with an gravity in the range 1050 to 1055º - were pitched at 58-60º F and ideally not allowed to heat up past 66º F, 70º F at an absolute maximum. Temperatures any higher were too likely to lead to an infection. Strong beers were pitched a couple of degrees cooler and, protected by their higher alcohol content, could be allowed to rise to a maximum of 75º F.

The Fuller's logs from 1910 confirm these pitching and fermentation temperatures. All the worts were pitched at either 59 or 60º F and the maximum temperature reached during fermentation between 66 and 69º F.

If a fermentation were not vigorous enough and the yeast head discoloured, the solution was to "dress" the wort. The old method was to mix 1 lb of wheat flour and 4 ounces of salt per barrel into the wort and then rouse it thoroughly. When the problem was caused by too many unfermentable carbohydrates in the wort, this "dressing" could be effective. The diastase in the malt acted on the carbohydrates, making them more fermentable. The new method was to use just malt flour, without any salt.

The appearance of the head when through a series phases during fermentation:

- after 2-3 hours, bubbles of CO2 began to appear
- after 4-6 hours, a head formed around the edges of the vessel and gradually covered the whole surface
- as the head thickened, it entered the "cauliflower" stage
- next was the "rocky head" stage, when it reached a height of three or four feet
- after about 48 hours the had began to collapse and the "yeasty head" stage began, also known as the "skimming point" as this was when skimming began. It was also when yeast was harvested.

The appearance of the "yeasty head" was an indication that it was time to start cleansing or skimming, if either of these systems of fermentation were being used. The gravity had by now dropped to between a third and a half of the starting gravity.

There were three systems of fermentation:

- the cleansing system
- the skimming system
- Yorkshire squares


But you'll have to wait until tomorrow for a detailed explanation of the fermenting systems.