The Rise of Yeast and an Attempt to Reclaim Ancient Egyptian Yeast
This time of year seems to bring new developments in the world of grains and bread. :Last year we learned of the discovery of 14,400 year old bread which is an incredibly important and illuminating find. This year we hear about yeast being extracted from ancient egyptian ceramics for use in bread baking…but is it the real thing?
While it is definitely a good idea(One I’ve pondered over the years from various angles) the yeast that was extracted recently is still undergoing genomic testing to see how old the yeast actually is. You see one of the difficulties in a project like this is that yeast are floating around all over the place so without genomic testing to verify you can’t assume the yeast that they captured didn’t blow/fall into the jar at a much sooner date. I guess we’ll have to wait and see.
That said, as a professional baker and baking educator for over 15 years and someone with fairly extensive experience and knowledge with brewing arts, I have studied and thought a lot about yeast. While by no means do I have all the answers I have certainly come up with some interesting questions and observations that don’t seem to be answered in the scientific literature and perhaps will be illuminating in several ways.
First of all, if you have brewed beer and baked bread you’ll notice an interesting difference. You can order “strains” or “cultivars” of beer yeast in dozens of distinctly different types that produce distinctly different outcomes of flavor and dryness in the finished product. For instance you can get ale yeast from california, belgium and england and they all produce a particular style of ale notably different in flavor. For bread yeast we have far fewer selections. There are sourdough starters which include a wide variety of microbes but most importantly yeast and lactobacillus. This must be made at home or gotten from a baker friend or bakery. The other option is commercially produced bread yeast. While it comes in several forms( fresh caked, active dry, instant) the “cultivar” is essentially the same and the results are essentially indistinguishable.(read my piece on yeast selection if you want to save a lot of time, heart ache and money in the next mailing).
At first glance this may seem odd but it has some logistical/pragmatic reasons. Beer brewing is innately isolating of strains due to the fact that the propagation medium(wort) is sterilized through the boiling process it undergoes before the yeast is added. In baking the propagation medium is not sterilized as raw wheat berries are ground into flour incorporating all the microbes on the surface of the wheat berries of which there are hundreds or thousands on each little berry. This is why when you stir flour together with water it will bubble after a few days and if fed it will be pumping with microbes by 2 weeks.
Furthermore when bread is baked the yeast stays in the bread and is killed by the baking process whereas in brewing, the yeast settle to the bottom or rise to the top and are filtered out leaving behind loads of yeast after each brew. By 1846 so many commercial bakeries were using the top fermented or “ale yeast” that when breweries began switching to lager yeast a hole formed in the market for “baking” yeast that was filled by the austrian innovators who created the vienna process by which bread baking yeast was specifically cultivated and produced to sell to bakeries. Eventually pressed cake yeast was produced and then “active dry” was created during world war II to make it more shelf stable and eventually instant yeast was created in the early 1970’s.
So in sum brewing naturally creates distinct strains of yeast that are now being maintained and expanded upon by breweries, home brewers, and commercial yeast producers that cater to all these markets whereas in baking, each new batch adds thousands of microbes that can potentially throw off the isolation and development of any given strain.
When I first realized this many years ago while I was running Wheatberry Bakery I thought if bakers back in the 1800’s were buying ale yeast from breweries to great success surely I could do the same and possibly realize the differences in flavor and dough development from different strains of ale yeast.
Using very high quality ale yeast I began experimenting but was really surprised at the results. Nothing. The yeast did not multiply. The dough did not rise.
This was discouraging and I was extremely busy with other things so I dropped the project. But it has always remained a curiosity. Had beer and bread yeast strains changed so much in the past 150 years that they were no longer compatible? Will anyone ever develop new strains of bread yeast to give bakers more choice in flavor profiles than we have currently?
I’m curious to hear your thoughts on the subject as I am sure I have some incredibly intelligent and learned readers out there. Feel free to share in the comments below!