[quote=“Brew On”]Here is a question for the brewing history aficionados.
Most bottom-fermenting breweries would have been using pure yeast strains. Big breweries would have propagated the yeast themselves using Hansen’s apparatus or something similar. Smaller breweries would have bought it. There’s a whole chapter on yeast propagation in “The American Handy Book of Brewing, Malting and Auxiliary Trades” by Wahl and Henius, published in 1902.
Ale brewers would have been less likely to use a pure yeast culture. Especially one making genuine aged Stock Ales, as you can’t get a true secondary fermentation from a pure strain. That’s one of the reasons British brewers were so slow to move over to single-strain pitching cultures. Some still haven’t even today.
In the earlier 19th century, British brewers often used yeast from other brewers. In the 1850’s William Younger used yeast from just about every brewery in Edinburgh. Except their own. Sometimes half of a brew was fermented with one brewery’s yeast and the other half with another’s.