Monday, 21 March 2016

Guinness’s Park Royal Brewery in 1949 – the brew house (part nine)

We’re almost finished with the fermenting arrangements at Park Royal. Just the fascinating matter of yeast collection and processing.

We start with the yeast collection vessels:

“There are two stainless-steel enclosed cylindrical yeast collecting vessels each of 200 cu. ft. capacity, i.e. 400 cu. ft. for three skimmers holding some 1,275 barrels of beer. These collecting vessels are fitted with internal power-driven fob breakers for degassing the yeast by cutting it down as it enters the vessel. Continuous yeast collection can be carried out as one collecting vessel can be blown to the yeast presses while the other is being filled. The capacity of each pair of yeast collecting vessels is sufficient to take about 65 per cent, of the total yeast from three skimmers, as the yeast "broken down" by the fob breakers is about the same density as ordinary liquid yeast.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 285.

Presumably these two cylinders per 3-skimmer bank were being filled from the yeast troughs at the end of each skimmer.

Those fob breakers sounds dead handy. I should get myself one. How often have I thought: what I need now is a good fob breaker.

I’ve been having trouble imagining how these skimmers were arranged. This makes it clearer:

“As there are eight banks of skimmers there are 16 yeast collecting vessels in all, arranged in two aisles one on each side of the house. The vessels are equipped for pressure evacuation by air at 45 Ib. p.s.i.g., the yeast being blown to filter-cloth yeast presses. There are two blowing mains, one for "pitching," i.e. yeast used in the brewing process, and the other for surplus yeast. This ensures that a selected "pitching" crop can be isolated from collection in skimmer to pressing. The yeast-blowing mains are of tinned copper with rubber diaphragm valves and flexible rubber connections for connecting one vessel to either "pitching" or surplus yeast lines. The yeast vessels are scalded out with hot water at 190° F. after each brew.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 285.

Eight banks of skimmers, each consisting of three skimmers vertically spread across three storeys. It’s an odd arrangement. I’ve come across plenty of different cleansing systems, but never one like this. I assume that they had the same in their Dublin brewery. The photo archive on the Guinness website had a picture of one that seems to fit the description. Though only one skimmer is visible so you can’t see if it’s in a bank of three.

The presses were where the yeast was pressed to both remove wort and make the yeast more compact. Interesting to see how carefully they kept the pitching and surplus yeast apart.

More details about the presses and an intriguing mention of bottoms (stop sniggering at the back):

“The yeast presses are of the standard filter-cloth type cooled with chilled water at 45° F., there being one bank of four 9 cwt. presses for store or "pitching" yeast, this quantity being sufficient for two brews, which is necessary to maintain brewing over holiday week-ends. For the surplus yeast, there are seven 16 cwt. presses cooled with chilled water. All the above weights are of pressed yeast. The barm beer from the press is collected in welded mild-steel enclosed collecting vessels. All the bottoms from the fermenting tuns and the fermenting house vessels are collected in stainless-steel enclosed cylindrical-bottomed vessels and blown to the surplus yeast presses.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 285.

Right, so they’re collecting the barm beer from the presses and the bottoms of the fermenting tuns. But what are they doing with it? Is it being re-used or is it being discarded? Remember that Watneys collecting all this sort of crap and blended it into new brews. Did Guinness do the same? Perhaps the author is reluctant to admit it, because he’s a bit vague at this point.

The vat house next.

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