Tetley cask Bitter specifications (part six)

Phew.! We're at the last page of the Tetley's Bitter specifications. And it includes some of the best stuff. As you'll see in a moment. 

Well, straight away, really. As it's the very first detail line in the  first table. You might have noticed in the last post that two yeast strains were mentioned in the "Additions before collection" table. The way it's listed is slightly ambiguous. It could mean that these were alternative yeast strains and you could use either one or the other. This table makes clear that wasn't the case.

Because from the percentages listed that both strains were pitched together, in different amounts. This comes as quite a surprise. I didn't think any Big Six breweries were pitching more than one strain of yeast.

AB7 and AB9 are obviously Allied Breweries designations for the strains. Do they still exist? Is either of them still used to ferment Tetley's Bitter? I wouldn't like to guess.

14. PITCHING
a)Yeast strain	(AB7: 55 - 65%) Chain Former
	(AB9: 35 - 45%)
b) Slurry Composition/Yeast Viability	1:1, Yeast :Water. w/w / 5%
c) Pitching rate (lb/brl pressed)	0.625
d) Temperature (°F) (°C)	63/64 (17.2 - 17.8)
e) A fresh batch of culture yeast is grown up every 3 weeks.
Source:
Tetley Beer and Malt Specifications, 1985, beer page 4.

The pitching temperature is given as 63º F to 64º F. And what was it back in 1945? 64º F. Exactly the same.

15. FERMENTATION
a) Max. temperature (°F) (°C)	73°F (22.5°C)
b) Skim gravity/time from pitching	44 hrs.
c) Temp. & PG on emptying FV	55 +- 3°F (12.8°C)
	Target 1007.0 - 1008.0
d) Time in FV	5 days.
Source:
Tetley Beer and Malt Specifications, 1985, beer page 4.

The maximum temperature was a couple of degrees higher than in 1945, when it was 71º F, Not a huge difference. While the length of fermentation was, at seven days, two longer back just after the end of the war.

It's fascinating how much of the process had been mostly unchanged for forty years.