Medieval bakers used to buy yeast from brewers, who were skimming way more than they needed to pitch the next brew. It seems everybody knew about yeast, but it isn't always mentioned -- maybe just taken for granted. There were of course farmhouse bakers, without access to a village brewery, making sourdough, just as there were spontaneously fermented beers. But there seems always to have been a distinction between spontaneous and cultured fermentation of both bread and beer. Harold McGee says yeast production for baking was a specialized profession in Egypt by 300 BC. And the genetic studies of late prove that today's brewer's yeasts were selected and propagated many centuries before Pasteur identified the organisms.
So coolships likewise have a dual history, I suppose. Some brewers left them exposed to inoculate the wort like Lambic brewers today. Others must have learned early on to keep the wort protected on the coolship until it was ready to receive the culture yeast. One thing I find fascinating about this is its indication of the dichotomy between the Medieval urban and countryside economies: in towns we see specialized industries linked in trade networks (the places where you find beer and bread that are not wild fermented.) This may explain why beer and bread yeasts are so genetically uniform today: the yeast was traded in hubs of commerce and would quickly spread across Europe. The countryside, where estates were self sufficient, depended on local, wild organisms.
Note also that the more important Bavarian brewing statute historically is not the Reinheitsgebot but the 1553 prohibition of Summer brewing, in response to the inability to keep beer from being infected by wild yeast in the warm months. This was rescinded only in 1850 with the advent of refrigeration and modern brewing science.
Sorry for the dissertation, I think this is fascinating.
Topic: Newest Toy (Read 3799 times)
