Because, as well as blending pre-fermentation, there was a second blending post-fermentation. In the first, 3 gyles of 1113º, 1089.2º and 1038.2º were blended to create these three worts:
After fermentation, 69 barrels of Imperial stout were mixed into the other two Stouts. With this result:
Not sure why you’d do this rather than get the quantities and OGs you want in the pre-fermentation blending.
I know from a Truman square book that Double Stout at least sometimes was vatted. I’d guess for at least 12 months.
For recipe details, see the Imperial Stout recipe I published a while back.
|1890 Truman Double Stout|
|pale malt||12.75 lb||70.83%|
|brown malt||1.75 lb||9.72%|
|black malt||1.00 lb||5.56%|
|No. 3 invert sugar||2.50 lb||13.89%|
|Fuggles 120 mins||4.00 oz|
|Fuggles 60 mins||4.00 oz|
|Hallertau 30 mins||2.00 oz|
|Goldings dry hops||0.75 oz|
|Mash at||157º F|
|Sparge at||175º F|
|Boil time||120 minutes|
|pitching temp||60º F|
|Yeast||Wyeast 1099 Whitbread Ale|