Transcript of Mise en Podcast IPM Episode: Yeasty and Ready to Party
Transcribed by Lur
[Cheery upbeat music plays softly as Neon reads the introduction]
Neon: Sugar fungus! It sounds cute, but is it? Yes, it actually is, but that destroys the narrative, so for now it is a menace. One of the most studied organisms in history, this prevalent presence has the staying power of a common cold. If left unchecked, it could devour all of the things that we love, but in reality, it just makes the things we devour all the better. Welcome to the wonderful world of yeast.
[Music swells and continues to play for a bit before fading out as Neon begins to speak]
Neon: Hi there. I’m Neon and welcome to Mise en Podcast.
I’m going to be your guide into this special deep dive into the history of yeast, the impact it’s had on humanity, how modern bakers yeast came to be, and how it affects nearly everything we do.
For those who are listening to us for the first time, welcome! I hope you enjoy this deep dive that was written for International Podcast Month 2019. If you’re listening to this on our regular feed, I’m glad to have you back. This episode is a bit of a departure from how we normally structure our episodes. My aim here is to show how important the sugar fungus has been to humanity and to give it the love it deserves. It’s really an unsung hero amongst history and civilization. I can’t resist jumping into some technical, scientific explanations, but fear not, we’ll have a break down to put things into perspective. For this episode, I reached out to numerous people to help me understand many of the more nuanced things when it comes to yeast, and without them, this episode wouldn’t be possible. I would like to give a huge thank you to Hannah Wright, without whom I would be lost in a world of chemistry that I don’t understand. Hannah was able to put me in touch with Jen Grennich, who helped me understand more about the different strains of yeast. You can find her on twitter @JenLovesBugs, which, if I’m being honest, is an amazing username. And a huge thanks to Wing McCallister for turning the jumble of words that I put on paper into an intelligible translation that normal people can understand. In addition to the wonderful help I’ve received on this episode, I pulled a lot of info from various places around the internet. I’ve included a full list of links to my resources on our site at bakecast.com. There is a link to this episode’s bibliography as well as the full show notes and transcript available there.
With that, let’s talk about Saccharomyces cerevisiae, better known as Yeast. In all fairness, when I say “yeast,” I am referring to what we all know. I use it as a catch-all to talk about the yeast we use in bread making and alcohol production. However, the word yeast is a bit of a misnomer. Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and 1,500 species are currently identified. Not all of them are used in baking! In fact, just a couple of strains give us beautifully risen bread or that bubbly glass of champagne. Yeasts have been around for a very long time, but how did they earn the baker’s admiration?
It is often postulated that man ceased their nomadic wanderings because they needed to grow crops for making bread. But it’s also suggested that the real reason to settling down was because man loves booze. To me, that one makes a lot more sense. Baking processes are amazing. They help provide a lot of the nourishment we use to survive, but at the end of the day, we are creatures who seek pleasure. And alcohol is an easy gateway to that. Nonetheless, it is agreed that yeast was more or less the catalyst that led to us establishing settlements and civilizations. For something we can’t see without a microscope, yeast has had a huge impact on our entire species!
One of my sources for this episode said the following. “For a long time, humans traveled often and foraged for food, rather than growing it. And that worked pretty well, so anthropologists have long puzzled over why people started settling in a single spot. One benefit to nesting: growing grapes and grains, and staying in a place long enough to brew beverages for weeks or months, as beer and wine require. ‘Some posit this as the reason that civilization began in villages surrounded by golden fields of barley and rows of grapevines on the hills.’”
So, we settled down and begin growing crops and brewing our own fermented drinks and making… well, not really bread, but something akin to it. We don’t have any leaven yet. Look! A new word!
For starters, let’s begin with leavening agents. These are either chemical, biological, or mechanical agents that are used to help baked goods rise. Chemical agents that are generally used are either baking soda (also known as sodium bicarbonate) or baking powder. Biological agents include baker’s yeast, preferments (like sourdough starter, poolish, or biga), beer, and even buttermilk or yogurt. Finally, mechanical leavening is provided by things like creaming butter, sugar, whipped eggs, or just egg whites.. All of these serve to add volume to baked goods.
Leaven can also refer to a specific form of preferment that is treated similarly to a sourdough starter. I’ve included a link with a list of various preferments in the shownotes. Traditionally, leaven (or levain) is held in reserve and fed daily. In this sense, it’s like a sourdough starter as bakers can always have a batch ready to use. In the US, we tend to use all of these terms interchangeably. However, for those who live in Europe, you might be cringing at my flippant use of both words. Let me share what King Arthur Flour says about this:
The words sourdough and levain tend to have the same meaning in the United States, and are often used interchangeably. This however is not the case in Europe. In Germany, the word sourdough (sauerteig) always refers to a culture of rye flour and water. In France, on the other hand, the word “levain” refers to a culture that is entirely or almost entirely made of white flour. While outwardly these two methods are different, there are a number of similarities between sourdough and levain. Most important is that each is a culture of naturally occurring yeasts and bacteria that have the capacity to both leaven and flavor bread. A German-style culture is made using all rye flour and water. A levain culture may begin with a high percentage of rye flour, or with all white flour. In any case, it eventually is maintained with all or almost all white flour. While a rye culture is always of comparatively stiff texture, a levain culture can be of either loose or stiff texture (a range of 50% hydration to 125% hydration). With either method, the principle is the same. The baker mixes a small paste or dough of flour and water, freshens it with new food and water on a consistent schedule, and develops a colony of microorganisms that ferment and multiply. In order to retain the purity of the culture, a small portion of ripe starter is taken off before the mixing of the final dough. This portion is held back, uncontaminated by yeast, salt, or other additions to the final dough, and used to begin the next batch of bread.
For us Americans, this distinction can seem a bit… nit-picky. But, I understand that these differences are important for others, and I am happy to acknowledge this difference!
All of that is to say that, while there are many reasons for people to settle down and cease their nomadic wanderings, I am of the opinion that the production of alcohol was one of the main driving forces behind that. And we have our friendly wild yeast to thank for that!
So, we’ve started to settle down and build our various civilizations. We started producing food and various types of bread. But when I say we, I am really talking about ancient cultures. Some of the earliest recorded bread production can be traced back to ancient Egypt!
Research shows that Ancient Egypt was the home of modern bread. Archaeologists digging in Egyptian ruins found grinding stones and baking chambers, as well as drawings of 4,000-year-old bakeries and breweries.
During this time, bakers were using different grains to create a variety of flavors in their breads. Wheat, which was the most common grain in Egypt, made excellent loaves.To make their breads tastier, bakers began experimenting with different ingredients. Honey, eggs, dates, seeds, and spices were added to provide a welcome and delicious variety of choices.
They would also often make their breads in different animal shapes – like birds, fish, and cows. While these breads were meant for everyday consumption, some had special significance for rituals and festivals.
Of course, that tradition continues with certain holiday animal-shaped breads. You can find a link to a page that talks about various shapes that bread can take, and the meaning or symbolism behind them, in the show notes.
Man has been making bread for thousands of years! Bread and alcohol are some of our oldest foodstuffs and they’re all centered around Saccharomyces cerevisiae.
Let’s talk about bread in Ancient Egypt for a bit as I find this absolutely fascinating! Here is something I love making and it’s been around for millennia! Not only was bread a staple of the Egyptian diet, but there is some evidence that Egyptians also produced pastries and sweets. What evidence you ask? The dentist money maker: tooth decay. However, the bread itself could have generated these ancient dental woes. It turns out that sand often made its way into the flour mixes, and Ancient Egyptians had trouble eliminating the pesky contaminant. This could lead to rapid tooth decay as well, though it’d be nice to ponder an ancient origin for all of our sweet teeth. Since I found only one source that mentions that, there is still some room for improved knowledge. Another source cites the importance of bread and beer in the production of the pyramids. They say that, contrary to popular belief, the pyramids were built by an army of workers paid daily in bread (or a measure of grain) and beer. However, I can’t find any other sources that make mention of this. But it is worth noting that workers across the Kingdom were paid in bread. Here’s something that was mentioned as well about the importance of bread in Ancient Egypt:
“The bread also held a religious importance. While exploring Mentuhotep II’s mortuary temple, archaeologists found a loaf of bread that was over 4000 years old. It was placed with other objects under the foundation of the temple in Western Thebes. The temple itself was believed to be a microcosm of the universe, and sitting in one of the four corners was a piece of Ancient Egyptian bread. This symbolizes the important value of the dietary staple.”
Well, we’ve talked about that long enough! It’s time to move on.
We can track a lot of our history through the trajectories of bread baking and beer making. Yeast was discovered long before humans had an understanding of microbiology. The process of providing leavening to bread was possibly considered a magical phenomenon, and yet, someone eventually figured out how to use a levain. Innovation never ceases, and things really took off when a good batch of wine or beer was used to provide the lift in bread for the first time. In the first century BCE, it is said that bread was made in Gaul and Iberia using beer foam, i.e. the head formed on the top of the beverage during its fermentation. In Roman times, Pliny the Elder wrote about bread dough that incorporated beer froth for lightness. The Romans themselves sometimes used a leaven made of grape juice and millet to hasten the fermentation of their breads. The juice contained yeast from the skins of the grapes. Barm, the foam that forms on beer during fermentation, was used as leaven by the Celts in Britain. With so many examples, it’s safe to say that liquid mirth would have been a primary source of yeast for many, many years. I find it fascinating that a lot of different groups from various parts of the world were figuring out these things at around the same time. I guess it goes to show that there was a real want or need for something other than hard, unleavened bread.
As I look around the internet at the history of both alcohol, beer specifically, and bread, I find it interesting that there are also records regarding the agricultural revolution, or the transition from nomadic hunting to permanent farming communities. Humans began to cultivate grains, and when these grains fermented, the seeds of brewing were sown. The earliest records date back to 4000BCE when the Sumer people in Mesopotamia fermented bread to create a “divine drink”. So beer was made with bread! It’s almost like I planned this topic unification. This helps explain why the same sugar fungus was used to brew the booze we love and make the bread we munch!
And this trend continued for some time! By the time the colonists made their way to the New World, the yeast organism had been identified and the brewing industry had begun. A byproduct of beer making was brewer’s yeast that could be used as a starter for bread. The yeast floated in the top of the beer and was skimmed off and put into stone bottles. Bakers could buy their yeast from a local brewery or make a ”brew” at home. Unfortunately, brewer’s yeast had one drawback; it frequently had a bitter taste that was imparted to the bread.
Besides brewer’s yeast, homemakers in the 19th century used specially brewed ferments to make yeast. The basis for most of these ferments was a mash of grain, flour, or boiled potatoes. Hops were often included to prevent sourness. Over time, the strong connection between brewers and bakers waned due to the implementation of new practices.
Here’s what Wikipedia says about this divergence:
In the 19th century, bread bakers obtained their yeast from beer brewers, and this led to sweet-fermented breads such as the Imperial “Kaisersemmel” roll, which in general lacked the sourness created by the acidification typical of Lactobacillus. However, beer brewers slowly switched from top-fermenting (S. cerevisiae) to bottom-fermenting (S. pastorianus) yeast and this created a shortage of yeast for making bread, so the Vienna Process was developed in 1846. While the innovation is often popularly credited for using steam in baking ovens, leading to a different crust characteristic, it is notable for including procedures for high milling of grains, cracking them incrementally instead of mashing them with one pass; as well as better processes for growing and harvesting top-fermenting yeasts, known as press-yeast.
Another source offers this explanation along with a more specific reasoning as to why the divergence happened.
“Although the process of brewing beer and baking bread began to evolve separately after Ancient Egypt, the industries remained mutualistic up until quite recently. Bakers could produce sourdough bread from wild fermentation (containing a mix of bacteria and wild yeast), or obtain relatively pure yeast from brewers. As brewing technology improved during the industrial revolution, it became possible to make bread that wasn’t sour because pure cultures of Saccharomyces cerevisiae could be obtained. In the 1800s, commercial bakeries got most of their yeast from breweries. However, as lagers replaced ales in popularity, bakers were forced to find new sources of yeast because lager yeast, Saccharomyces pastorianus, works much slower than ale yeasts and doesn’t produce good bread. This lead to the development of bread yeast as we know them today.”
And finally, I offer this from a third source:
“In the 19th century, bread bakers obtained their yeast from beer brewers from which they made sweet-fermented breads. This process, known as the Dutch process (because Dutch distillers were the first to begin selling yeast commercially), spread to Germany and yeast was sold as cream.”
That’s kind of a lot to take in, so let’s break things down a bit. Most of this seems pretty straightforward. For a long time, the left over ferment from making beer was used to help give bread its rise. As time went on, we were able to figure out what strain of yeast was working its magic, and we worked to isolate that strain. When lagers became more popular, the type of yeast that was used was changed. Bakers were left without their primary suppliers, so they needed to find another source of the yeast that’s good for baking. This is where that Vienna Process comes into play. Once again, our friend Wikipedia yields a technical definition.
“Vienna yeast was propagated utilizing a mash of malted corn, barley, and rye. Horsford did not assert hops were used in the production of press yeast. After pitching a small amount of yeast into the cooled wort, and introducing some air, the propagated yeast floated to the surface. This yeast was collected with some care by skimming. Cool, distilled water was used to wash and settle the yeast a sufficient number of times until only the yeast remained. It was then drained and compressed with the aid of a hydraulic press. Press-yeast was one forerunner to the modern, commercially available baker’s yeast.”
OK, basically, Austrian chemists developed a system for mass-producing yeast. The yeast was sown in vats containing fermenting brew. When it rose to the top, the yeast was removed and washed, and some of the water was removed. It was then formed into ready-to-use cakes.
There was a lot going on in a somewhat short time frame. Here’s a bit of a timeline on things. Tebbenhof was the first who, in 1825, found a way to make yeast into cube cakes by way of extracting moisture. In 1867, Reiminghaus used the filter press which allowed for improved industrial manufacture of baker’s yeast. The resulting Vienna Process spread throughout the French market, and this method of making yeast cakes is still used today throughout Europe. Charles Fleischmann brought method of making yeast to United States. He was trained as a young boy in a distillery, and he learned that yeast is a by-product of distilling.
For keen listeners, I just said a name that is very prevalent in today’s bread making society. Fleischmann. But, before we get into the innovations Mr. Fleischmann brought to the world, we need to talk about another rather famous individual who played a large part in yeast as we know it today. Louis Pasteur.
Louis Pasteur helped us understand how yeast worked in beer and wine. Here’s an excerpt talking about his research.
“Our modern understanding of the fermentation process comes from the work of the French chemist Louis Pasteur. Pasteur was the first to demonstrate experimentally that fermented beverages result from the action of living yeast transforming glucose into ethanol. Moreover, Pasteur demonstrated that only microorganisms are capable of converting sugars into alcohol from grape juice, and that the process occurs in the absence of oxygen. He concluded that fermentation is a vital process, and he defined it as respiration without air.”
Pasteur performed careful experiments and demonstrated that the end products of alcoholic fermentation are more numerous and complex than those initially reported. Along with alcohol and carbon dioxide, there were also significant amounts of glycerin, succinic acid, and amylic alcohol (some of these molecules were optical isomers — a characteristic of many important molecules required for life). These observations suggested that fermentation was an organic process. To confirm his hypothesis, Pasteur reproduced fermentation under experimental conditions, and his results showed that fermentation and yeast multiplication occur in parallel. He realized that fermentation is a consequence of the yeast multiplication, and the yeast have to be alive for alcohol to be produced. Pasteur published his seminal results in a preliminary paper in 1857 and in a final version in 1860.”
In 1856, a man named Bigo sought Pasteur’s help because he was having problems at his distillery, which produced alcohol from sugar beetroot fermentation. The contents of his fermentation containers were embittered, and instead of alcohol, he was obtaining a substance similar to sour milk. Pasteur analyzed the chemical contents of the sour substance and found that it contained a substantial amount of lactic acid instead of alcohol. When he compared the sediments from different containers under the microscope, he noticed that large amounts of yeast were visible in samples from the containers in which alcoholic fermentation had occurred. In contrast, in the polluted containers, the ones containing lactic acid, he observed “much smaller cells than the yeast.” Pasteur’s finding showed that there was another fermentation process at play. Alcoholic fermentation occurs by the action of yeast; lactic acid fermentation, by the action of bacteria.
Oh man. Now we’ve got lactic acid fermentation in the mix? Good news! I’m going to briefly describe it and what it’s used for, and then we’re going to move back to our sugary friends. Lactic acid fermentation as described by Wikipedia:
“Lactic acid fermentation is used in many areas of the world to produce foods that cannot be produced through other methods. The most commercially important genus of lactic acid-fermenting bacteria is Lactobacillus, though other bacteria and even yeast are sometimes used. Two of the most common applications of lactic acid fermentation are in the production of yogurt and sauerkraut.”
Now that we’ve got that out of the way, let’s talk about how Louis’s findings apply to baking.. Louis’s experiments proved (hehe… it’s a yeasty pun!) that yeast is a living organism that is responsible for fermentation. To put it into some simpler terms, yeast feeds on the starches in flour, producing carbon dioxide, which expands the gluten proteins in the flour. The gluten proteins cause the dough (of which flour is a main ingredient) to expand and rise.
We’ve now got an idea of how yeast does its thing, so let’s turn back to our timeline and pick things up six years after Pasteur’s discovery.
[Upbeat old timey polka music fades in and plays for a bit before fading to background music as Neon continues to talk]
Neon: In 1863, an immigrant named Charles Fleischmann went back to Austria to search for a good-quality baker’s yeast. He returned to America with the yeast cells in a test tube that he had placed in his vest pocket. In 1868, Fleischmann’s® Yeast was founded. The company began selling compressed yeast wrapped in tin foil, and the modern baking era was born.
[Music fades out completely]
Neon: With the onset of World War II, the U.S. government sought a dehydrated yeast that could be used to make bread on the battlefield. In 1943, Fleischmann`s company produced the first active dry yeast. After the war, dry yeast was introduced to the retail market and is now the form of yeast most commonly used for home baking.
That’s right. The packets (and jars) you see of Active Dry Yeast on the shelves of your local grocery store are a fairly recent invention. For as long as yeast has been around in the wild, it’s only been within the past 80 years that things have taken off with regards to use and availability. Personally, I love that this tiny fungus has done so much for us. And we’re at the point where we have different options of yeast available for us. I’m not going to go into detail about the yeast used in the production of alcohol, as we’ve mostly been talking about baking. That doesn’t mean it’s not important, but I don’t have the time to go into all of the varieties out there.
Let’s talk about what you can find on the shelves for the home baker.
First, we have cream yeast. It’s the closest form to the yeast of the 19th century. Basically, it’s a suspension of yeast cells in liquid, taken from the growth medium. Cream yeast is used in industrial bakeries with professional dispensing and mixing equipment, and it is rarely used in small bakeries or by home cooks.
From there, we’ve got compressed yeast. Compressed yeast is made from cream yeast after most of the liquid is drained. This is made for both industrial and home use.
Active dry yeast is probably the variety you’re most familiar with. It’s those coarse, oblong granules of yeast, which have live yeast cells encapsulated in a thick jacket of dry, dead cells. It must first be rehydrated before use. Stored at room temperature it can last for a year. Frozen, it can last 10 years or more.
Instant yeast is another familiar one. It looks like active dry yeast, but the granules are smaller in diameter. It also lasts for a much shorter time. It doesn’t have to be rehydrated before use. Both active dry and instant yeasts are used primarily at home. The small bakery I work in uses both, so they have some commercial applications too.
Finally, we have rapid-rise yeast. This is a type of dried yeast that is of similar granular size, and can be dissolved faster in dough. It produces more carbon dioxide than other yeast types which causes the dough to rise much faster when compared to other varieties. Rapid-rise yeast is often used in bread machines.
What a journey this has been! For me, I’ve enjoyed learning so much more about yeast than I even realized. Since this ended up being quite a deep dive, let’s end with a short recap!
In summary, yeasts are great for making bread, beer, and wine because they are good at harvesting energy from sugar without oxygen, through a process called fermentation. In addition to energy, fermentation produces two by-products: carbon dioxide, which produces the lift in leavened bread and the bubbles in beer; and ethanol, which adds interesting properties to wine and beer, but evaporates in the bread oven. The process is essentially the same for all three foods: fermentation by friendly microbes and a form of controlled spoilage. During fermentation, the yeast also produce many enticing flavors not originally found in wheat, barley, or grapes, as anyone can attest who’s been intoxicated by the smell of fresh yeast bread, or appreciated how a glass of fine wine differs from a grape.
So there you have it. Yeasts are a huge group of (usually) single-celled, fungi that (usually) reproduce by budding. They’re not all closely related, and some of them moonlight as filamentous fungi, which we didn’t talk about at all, but it sounds cool. Some are good at turning sugar into ethanol, a few of which we have domesticated. For all their hard work, we often reward yeasts with death in a fiery oven, or with drowning in their own poisonous waste. But without them and their revolutionary food products, it’s safe to say that the history of cooking — and history, period — would be a radically different tale.
And that’s it, folks! I would like to thank you all for joining us on this fun dive into the history of yeast and how it’s helped change our world. If you’d like to listen to more shows or see what we’re about, check us out at bakecast.com. Happy baking everyone!
Lur: This International Podcast Month episode of Mise en Podcast was written, edited, and produced by Neon. You can find her on twitter, @NeonGreenTiger. Script editing was by Wing McCallister. You can find him on twitter @DrWingMC. Art is drawn by Dan Stewart. Find him on Twitter @BlueDustbunny. Transcription services provided by Lur.
Music is Cheery Monday by Kevin MacLeod from incomptech.com and used under the Creative Commons Attribution License.
Special thanks to Amanda McLoughlin, Hannah Wright, Jen Greenwich, and the International Podcast Month team.
For all other information, including episode transcripts, links, and show notes, please visit our website at bakecast.com. You can also find us on twitter @MiseEnPodcast, or write to us at firstname.lastname@example.org. Hungry for more episodes? You can find us on RadioPublic, Spotify, iTunes, Google Play, or your favorite podcasting app.
Want to help support us financially? Check out bakecast.com/support. There, you can find a variety of methods including a Patreon with various tiers and rewards. If monetary support is not your thing, please tell your friends about us. And please remember to leave a rating and review on iTunes. These help motivate Neon and give her many emotions. Plus, they help others find the show!
As for me, I’m Lur. And I’m a foaming mass of microorganisms in an evening gown.