Because the lactose wasn’t added in the copper, as you might expect, but at racking time in the form of primings. Meaning it was no problem to parti-gyle it with other beers. Before the addition of lactose, the rate of attenuation of Mackeson was very similar to that of London Stout, somewhere around 70%.
For something which today would be described as a Sweet Stout, this version of Mackeson is surprisingly robustly hopped. And, even after the addition of the lactose, the rate of attenuation isn’t that low – still over 60%. Far greater than the ridiculously under-attenuated Sweet Stouts to be found at the time in Scotland. Meaning the finished beer probably tasted bitter-sweet rather than just overpoweringly sweet.
Whitbread were already brewing large quantities of Mackeson before the war. It was a beer very much in vogue and, like Bass and Guinness, was also sold in other breweries’ tied houses. A sure sign of a beer that was a cut above the norm.
|1940 Whitbread Mackeson Stout|
|pale malt||9.00 lb||70.98%|
|brown malt||1.00 lb||7.89%|
|chocolate malt||1.00 lb||7.89%|
|flaked oats||0.10 lb||0.79%|
|No. 3 invert sugar||0.50 lb||3.94%|
|caramel 1000 SRM||0.33 lb||2.60%|
|Fuggles 75 mins||1.50 oz|
|Goldings 30 mins||1.50 oz|
|Mash at||150º F|
|Sparge at||170º F|
|Boil time||75 minutes|
|pitching temp||62º F|
|Yeast||Wyeast 1099 Whitbread Ale|