So how do you get from sourdoughs, starters and barms to packaged yeast…and what’s the difference anyway? Both good questions, the answers to which, pleasantly enough, start with beer.
Brewing, as many of you already know, is an extremely ancient art. It dates back at least as far as the Egyptians (likely much further, though they’re the ones with the written records). Like bread making, brewing depends on the action of yeast (fermentation), only instead of a mostly dry medium, the yeast work in a liquid medium. The upshot of this is the yeast “breathe” less, produce less carbon dioxide, but much more alcohol (to the delight of all concerned). Essentially beer is made by mashing malted (sprouted) grain and leaving it to soak. The soaking encourages the grain’s enzymes to break down the starch (just as in bread) and convert it into simple sugars. Strained, the resulting sweet liquid is known as “wort”. The next step is boiling the wort with hops to deactivate the enzymes and remove any rank flavors (that’s what hops are mostly for). The resulting brew is then left to ferment into beer.
This can take many days, over which time the beer is usually skimmed of the yeasty foam (barm) that collects on the top. The reason, because like a bread starter, lots of other microbes are present in it, notably lactic acid bacteria, which give the beer an unpleasant acidic tang if they aren’t removed. The main by-products of the beer-making process are therefore dense cultures of fermenting microbes, which when added to bread dough result in a terrific rise. Thus throughout recorded history, wherever you find beer, you find bread.
So then people went to breweries to get their yeast in the old days? Depending on the society and the time period in which they lived, yes. However most people who drank beer in the pre-industrial ages simply made their own (or perhaps lived and worked on an estate on which the landlord’s kitchen brewed its own…plus made its own wine, baked its own bread, butchered its own meat…you get the idea). Back-country peasants generally did without luxuries like beer, and hence ate very dense breads leavened by the sourdough method alone.
So you see that in many respects beer and bread went hand-in-hand. But then how do we get from goopy beer barms to cake and/or dried yeast? For that we need to look to the historical epicenter of all that was good and noble in the baking and pastry arts: the Austro-Hungarian Empire and its capital, Vienna. For it was there (or thereabouts) that chemists first isolated yeast (you mean it’s a microbe???) and turned it into the compressed cakes that were so popular from the mid-1800’s all the way up until roughly World War II. That’s when Fleischmann’s Yeast, a company founded by two Austrian brothers in Cinncinnati in 1868, invented active dry yeast so soldiers could enjoy a little taste of home in the field.
The 1980’s witnessed the next great advancement in the world of commercial yeast with the invention of “instant” yeast. Invented by the Dutch (no slouches themselves at fermenting yeast), it can be added directly to bread doughs without having to “prove” it in warm water first. It therefore provides all the ease-of-use of fresh cake yeast (still favored by most professional bakeries) with the store-ability of active dry.