Chapter 19: Fungi in Food Processing

Welcome to Last Minute Lecture.

This free chapter overview is designed to help students review and understand key concepts.

These summaries supplement not replaced the original textbook and may not be redistributed or resold.

For complete coverage, always consult the official text.

Welcome, curious minds.

Have you ever stopped to consider the silent partners behind some of your absolute favorite foods?

We're talking about invisible architects, really.

Things like your morning toast, that glass of wine, maybe even that pungent blue cheese you might have on a platter.

Today we're taking a deep dive into chapter 19 of Bryce Kendrick's The Fifth Kingdom.

It's a fantastic book if you want to get into the microbial world.

And this chapter is all about fungi in food processing.

So our mission today is basically to uncover how these microscopic maestros, these tiny little organisms, transform everyday stuff into culinary delights.

We want to make it really clear and engaging for you, our listener, without needing a single diagram.

Think of it as a bit of a shortcut to really getting the science behind what's in your pantry.

Yeah, what's truly fascinating here, and honestly often overlooked, is just how profoundly fungi shape our diet.

Even when we don't really think about it, it's so much more than just eating a mushroom from the grocery store.

It's about the fundamental, almost kind of magical changes they bring to a raw ingredient, the substrate.

They often create entirely new products that just wouldn't exist otherwise.

I mean, just consider the huge difference between,

say, a bland, unleavened cracker and a really crusty baguette, or grape juice versus a complex wine.

From the absolute basics in our meals to some really specialized gourmet treats, fungi are working away, often completely unseen.

Okay, so if we want to understand these kind chefs, where's the best place to start, for someone maybe just dipping their toes into this whole world?

Well, let's start with something pretty much universally loved and recognized.

Bread, you know, that incredible airy texture, all those bubbles that make it so satisfying.

That's not some fancy baking trick.

It's actually the ingenious work of yeast.

Ah, yeast.

And specifically, we're talking about saccharomyces cerevisia, right?

That's a bit of a mouthful, but it's the key player for that rise.

So how does this tiny thing do such a big job?

Exactly.

Saccharomyces cerevisia is the star here.

What it does is it ferments the small amounts of sugars that are naturally in the dough or sometimes added.

As it does this, it releases countless tiny bubbles of carbon dioxide gas, CO2.

Now try to picture this.

The dough is the sticky elastic network, right?

Almost like a stretchy sponge.

These little gas bubbles get trapped inside that network and that causes the dough to slowly inflate, become light and puffy.

That whole process is what we call leavening.

Without that yeast action, French bread would be more like a matzo, you know, flat and dense.

That's a great way to picture it.

Okay, so the same little yeast, saccharomyces, it's also the genius behind all alcoholic drinks.

At its core, it's taking sugar, turning it into alcohol and carbon dioxide.

Simple idea, but I guess the biology is more complex.

Like you mentioned, it involves a sophisticated biological dance, lots of enzymes.

Over 20?

That's right.

The basic equation is simple.

Sugar becomes alcohol and CO2.

But biologically, yeah, it's a complex pathway.

22 enzymes, other intermediate steps.

It's a quite intricate cellular machinery at work.

Right.

Now, a common question we probably get is, if bread uses the same yeast, how come it doesn't have alcohol in it?

Ah, yeah, that's a fair question.

And the answer is actually pretty straightforward.

The alcohol that is produced during the bread fermentation simply evaporates away during the baking process because of the heat.

So yeah, no need to worry.

Your morning toast isn't going to get you tipsy.

This whole transformation process, by the way, it's ancient, goes back thousands of years.

Okay, so we've seen yeast turning dough into fluffy bread.

Super versatile.

But what happens when we apply that same fermentation magic, that same saccharomyces action to things like grains or fruit juice, specifically grape juice, that's where we get into the whole chemical symphony of wine and the really complex world of beer.

Let's talk beer first.

Beer production is fascinating.

It usually starts with malting barley.

What malting does is activate the barley's own natural enzymes called amylases.

These enzymes then break down the starches in the grain into simpler sugars.

And those sugars are perfect food for the yeast.

Then specific yeast come into play.

For instance,

saccharomyces, Carlsbergensis, yeah, another long name, but that's the yeast that typically gives bloggers their crisp, clean finish.

You find it in lots of those cold carbonated European styles.

Then for ales, you often use saccharomyces cerevisiae, the same species as bread yeast, but different strains.

And these give you a much wider spectrum of flavors.

Think earthy British bitters, fruity IPAs.

It's actually incredible how just tweaking the yeast strain, the fermentation conditions like temperature can produce such wildly different beers from similar starting points.

That's a really great point about control and tweaking things.

Okay, so from beer, let's pivot to wine.

Wine often feels like this blend of tradition and art, right?

But how much of making a truly great wine is still down to chance like it used to be?

And how much has science really taken over?

That's a fantastic question, because winemaking really does sit at that crossroads of art and science.

For thousands of years, winemakers basically just crushed grapes, making this liquid called must, and then they just hoped for the best, relying on the wild yeasts naturally present on the grape skins to do the fermentation.

It was definitely a bit of a gamble.

But this reliance on luck, it was completely changed back in 1866.

Louis Pasteur published this classic paper, etudes sur l 'hiver.

He showed that specific yeast strains were responsible for good wine, and that other microbes, bad ones, caused spoilage.

That discovery essentially put winemaking on a proper scientific footing.

It allowed for much greater consistency and, frankly, better quality control.

Right.

So Pasteur was a total game changer there.

But beyond just the yeast, what else really makes a great wine?

Kendrick's book highlights five key factors.

What's maybe one that might surprise people or one that's often underestimated?

Well, things like the grape species, you know, vitus vinifera varieties like Pinot Noir, Cabernet Sauvignon, Chardonnay, those are obviously critical.

And climate, of course, getting that balance of warmth for sugar and coolness for acidity.

But the terroir, the soil, that's often underestimated.

Picture the finest burgundies, right?

They often grow in soils that look pretty poor, maybe stony, with limestone rocks.

It isn't really about fertility in the usual sense.

It's about excellent drainage that forces the vine roots to grow really deep, searching for water and nutrients.

And as they do, they absorb unique minerals from those deeper soil layers, which contribute these subtle complex nuances to the wine's final flavor.

It's almost like the earth itself is, I don't know, whispering secrets into the grapes.

The very ground influences the taste that much.

What about the actual winemaking process now?

Beyond pasture, figuring out the right yeast was key.

Right.

That's factor four, the yeast itself and how it's managed.

Historically, it was potluck with wild yeasts, hoping Saccharomyces cerevisia var ellipsoideus dominated.

But today, most winemakers play it safer.

They often suppress those unpredictable wild yeasts, usually using a bit of sulfur dioxide.

Then they add pure cultures of highly selected specific wine yeast strains.

They know exactly what characteristics those strains will bring, and they often keep the fermentation relatively cool.

Doing that boosts the production of these tiny aromatic compounds, things like esters.

These compounds are largely responsible for the wine's specific bouquet, its aroma profile.

So this scientific precision lets them reliably create those wonderful flavors we expect from fine wines.

Okay.

And the fifth factor, age and storage.

That seems to bring us back towards the art side of things again, right?

Patient.

Absolutely.

Some wines, like maybe a light Beaujolais, are made to be drunk, young and fresh.

But then you have something like a big Cabernet Sauvignon.

It contains this complex mix of chemicals, tannins, acids that really needs years to mature properly.

Often that involves aging in oak casks first.

The oak imparts tannins, which give the wine structure or firmness.

And then it needs several more years just resting in the bottle for all those flavors to blend, mellow and smooth out.

It needs time to reach its peak.

It really is a patient craft.

Definitely.

And beyond these sort of standard table wines, there are some truly unique wine creations out there too, again involving fungi or specific conditions.

Oh, absolutely.

There's a whole fascinating world of specialized wines.

You have fortified wines like Port and Sherry.

They're different because brandy is added during the process.

This boosts the alcohol content way up, usually to around 20 % compared to maybe 10, 14 % for regular table wine.

Sometimes that brandy is added before all the natural grape sugars have fermented, which stops the yeast and leaves you with those wonderfully rich sweet dessert wine styles.

Right, like a sweet port.

And then there's this amazing thing called noble rot.

Sounds like a contradiction.

Rot leading to something noble.

It absolutely does sound like one, but it's real.

It's caused by a very specific mold, a type of filamentous fungus called Botrytis senaria.

In French, they call it purateur noble.

In German, edelfeuille.

What happens is in certain years with the right weather conditions, usually misty mornings and sunny afternoons, grapes are deliberately left on the vines way past ripeness.

This Botrytis mold starts to grow on them.

It actually punctures the grape skins, making tiny holes.

Then as the sun comes out, water evaporates from the grapes through these holes, but the sugars get left behind and become incredibly concentrated.

The mold also consumes some acid and adds its own unique flavors.

Imagine these sort of shriveled moldy looking grapes, almost like fuzzy raisins.

They have to be picked very carefully, often one by one, right at the perfect stage.

This intense concentration creates these absolutely exquisite sweet wines, think Sotown from France, German Trockenbierenausles and Hungarian Toquet.

They have this amazing velvety texture, intense sweetness, but it's balanced by acidity, so it's not cloying.

Just incredible stuff.

What a process.

Wow.

And then there's also ice wine or ice vine.

Similar idea of leaving grapes out.

Yes, similar idea of extreme conditions, but different mechanism.

Again, grapes are left on the vine long past the normal harvest, but this time they wait until winter, until the grapes literally freeze solid on the vine, like little icy marbles.

They have to be picked quickly, usually in the dead of night or very early morning while they're still frozen solid and then pressed immediately.

The water crystals stay behind in the press as ice, but a tiny amount of incredibly concentrated sugary juice is squeezed out.

This makes a very rich, intensely sweet wine, again with balancing acidity.

Ontario Ice Wine, especially from the Vidal grape variety, is now considered some of the best in the world.

Really remarkable.

It's just amazing how much fungi influence these liquids we drink, and you're saying this hidden hand that stretches even further into spirits, the hard liqueurs.

That's right.

Think about whiskies.

They all start with yeast fermentation of grains.

Bourbon, for example, typically uses fermented corn mash.

Scotch uses fermented barley, often malted barley.

Rye whisky uses, well, fermented rye.

That initial fermented liquid, kind of like a basic beer, is then distilled.

Distillation concentrates the alcohol, usually up to around 40 % or so, and then things like aging add character.

For Scotch, the smoke from peat fires used to dry the malted barley, and then years aging in oat casks contribute hugely to its distinctive smoky, woody flavor profile.

And Kendrick even mentions a really unusual example, chicha del yauliao from Chile.

Apparently, the indigenous Iraqi people ferment these unusual, fleshy, almost mushroom -like structures of fruiting bodies, technically called ascomata of a fungus called Cetaria heriote.

These fungal bodies themselves contain quite a bit of fermentable carbohydrate, and apparently the natural yeast present in the fungus just get to work and ferment it.

Wow, fermenting the fungus itself.

Okay, moving on from all these incredible liquid creations, let's talk about something solid and utterly delectable for many.

Now, there are hundreds, maybe thousands of cheeses out there, but Kendrick points out that only a select few are actually processed by fungi.

But boy, are those few iconic.

We thought about two main types here, right?

Soft -ripened and the blue cheeses.

Exactly, and what's so fascinating is how very specific fungal species create such dramatically different textures and flavors.

Let's take the soft -ripened cheeses first.

Think Kemembert, think Brie.

These are ripened by molds like penicillium kememberti or penicillium caseolum.

These molds grow on the outside of the cheese, forming that characteristic dense white sort of velvety skin or rind.

Technically, it's a mycelial mat.

Now, the key thing is these molds release enzymes, extracellular proteases that slowly diffuse inward from the rind towards the center, and these enzymes break down the milk proteins, the casein.

They basically digest the cheese from the outside in.

So if you imagine cutting into a perfectly ripe Brie, you see that interior is wonderfully viscous, soft, almost fluid.

It might gently ooze out.

That's the magic of those fungal enzymes, creating that incredibly smooth, soft, almost buttery consistency.

Making me hungry.

And then, of course, the really vibrant pungent blue cheeses.

How do they get those striking blue -green veins and that very distinctive flavor?

Ah, yes, the blues, roquefort, stilton, gorgonzola.

These guys are ripened by a different mold, penicillium roquefortia.

During the cheese making process, they actually add bread crumbs that have been inoculated with p -roquefortia spores directly into the milk curd.

So the fungus is mixed throughout the cheese from the start.

Then, as the cheese ages, the mold grows within it.

Cheesemakers often punch holes into the cheese wheels partway through aging.

This allows air, oxygen to penetrate deeper into the cheese, which helps the penicillium grow even better, as it needs some oxygen, though it tolerates low levels.

Those characteristic blue -green veins, you see, they're literally dense patches of fungal growth, packed with millions upon millions of pigmented spores called knidia.

But this mold doesn't just change the look, it transforms the profile entirely.

P -roquefortia has enzymes that break down fats, oxidizing the fatty acids into compounds called methylketones.

One specific one, 2 -heptanone, is largely responsible for that really penetrating smell and the unique sharp, pungent flavor that people tend to either love or, well, maybe learn to love.

And importantly, Kendrick notes that while this mold can produce a mycotoxin called PR toxin under certain lab conditions, thankfully it doesn't seem to do so during the making process itself.

So these cheeses are perfectly safe and delicious.

That's good to know.

Okay, so we've covered a lot of the western world's greatest hits, if you will, for fungus -processed foods.

Bread, beer, wine, cheese.

But if we kind of shift our gaze eastward, we find this whole other universe of culinary innovation, where fungi have been absolutely central for millennia.

Is there a sort of core difference in how fungi are used in traditional eastern foods compared to the western examples we just talked about?

That's a really insightful question.

I think one key difference is that while western fermentation often focuses heavily on yeasts for alcohol or leavening and maybe molds for surface ripening, like in cheese, many traditional Asian foods rely extensively on filamentous molds, especially aspergillus species, specifically for pre -digestion and profound flavor transformation of plant -based protein sources, particularly soybeans.

The complexity of some of these processes is just astounding.

They've really mastered using molds to unlock nutrients and create umami.

Let's look at a couple of key examples.

Fantastic.

Where should we begin with these staple ingredients?

Well, we absolutely have to start with shoyu.

That's what we generally know as soy sauce.

It's so fundamental.

In Japanese cuisine, Kendrick mentions annual consumption is nearly 15 liters per person.

That's huge.

And the process is incredibly intricate.

It's not simple.

Basically, you have cooked soybeans mixed with roasted crushed wheat.

This mixture is inoculated with a specific mold, aspergillus or razee.

It's spread out on trays and incubated for maybe 18 days or so, allowing the mold to grow all through it.

This moldy mixture is called koji.

Then this koji is mixed with a strong salt brine, which stops the aspergillus but allows other microbes to work.

It's inoculated with a specific salt -tolerant yeast and lactobacillus bacteria.

This whole mash then ferments slowly in large vats for several months.

And finally, it's pressed, pasteurized, and matured for up to two years sometimes.

It's this incredibly long, complex, multi -stage microbial succession that creates that deep, savory umami flavor.

Truly a chemical masterpiece.

Wow.

Two years for soy sauce.

That is some serious dedication to flavor development.

Oh.

Okay.

What's another really important staple with a similar kind of fungal story?

Miso is probably second only to shoyu in importance in Japan.

It's that thick, savory paste, often used in soups and marinades.

It's also typically made from soybeans, sometimes mixed with rice or barley.

And again, aspergillus or aizai is the star player, used to make the initial koji, usually on steamed rice in this case.

This rice koji is then mixed with steamed mashed soybeans, salt, and usually another specific yeast, saccharomyces russi, which is also salt -tolerant.

This mixture is then packed tightly and left to ferment and ripen for weeks, months, or even years, depending on the type of miso.

Miso soup is, as you probably know, a daily staple for many in Japan.

It's nutritious, flavorful, a testament to the power of fungal fermentation.

Absolutely.

And beyond these, you know, well -known sauces and pastes, what about a food where the fungus really transforms into a notoriously difficult ingredient, making it easier to eat?

That brings us perfectly to tempeh.

It's often called Indonesian soybean cheese, though it's different from dairy cheese.

Tempeh is a brilliant example of using fungi to solve a nutritional problem.

Soybeans are nutritious, but they can be hard to digest, and some people find the flavor bland.

Tempeh production tackles this head -on.

Cooked, de -hulled soybeans are inoculated with a different fungus, Rhizopus oligosperus.

This fungus has incredibly fast -growing mycelium, those are the fine fungal threads.

Within about a day at warm temperatures, the mycelium grows throughout the cooked beans, binding them together into a firm cake.

Crucially, as it grows, Rhizopus pumps out extracellular proteases, those protein -digesting enzymes again.

These enzymes break down some of the complex soybean proteins, making them much more digestible.

The fungus also produces some vitamins and contributes a pleasant, nutty, slightly mushroomy flavor, especially when the tempeh cake is sliced and fried.

So it's not just fermentation for flavor, it's a significant nutritional upgrade, making soybeans more accessible and tasty.

There are other similar products, too, like Sufu in China, using Actinomacore, or Entrem from Peanut Waste using Neurospora.

That's a perfect example of fungi acting as, like, tiny biological processors.

So bringing this all together, what does this really mean for us?

Especially thinking about, you know, students trying to grasp this chapter.

I think the big takeaway is realizing that fungi aren't just ingredients in these foods.

They are active, transformative agents,

biological catalysts, if you like.

They break down complex molecules, starches, proteins, fats.

They create entirely new flavor and aroma compounds.

They change textures dramatically.

And, as we saw with tempeh, they can even make food significantly more digestible and nutritious.

So for you, the student listening, it's about thinking beyond just the surface of what you eat.

It's appreciating the intricate, often invisible, biological processes driven by these amazing fungi, processes that shape so much of our food culture, many of which we're actually only just beginning to fully understand and harness scientifically.

Absolutely.

It really drives home that from the simple rise of your morning coast to the incredible complexity in a glass of fine wine, or the sharp tang of blue cheese, or the deep savory notes in soy sauce, fungi are truly indispensable.

They're working behind the scenes in our global food landscape.

So just to quickly recap the big points we hit, we saw yeasts, mainly Saccharomyces cerevisiae, as these unseen workhorses.

They leaven our bread, making it light and airy.

And they ferment sugars into alcohol, giving us everything from crisp beers and complex wines right through to the base for distilled spirits.

Then there are specialized fungi, like Botrytis cinaria, the famous noble rot, creating unique, intensely sweet dessert wines by concentrating grape sugars under very specific, almost magical environmental conditions.

We also looked at molds, particularly penicillium species.

They gift us those distinct textures and pungent, delicious flavors we find in soft, ripened cheeses like Brie and Camembert, with their gooey centers, and of course the iconic blue cheeses with their striking veins and sharp taste.

And finally, we touched on that huge diversity of mostly filamentous fungi, like Aspergillus auricii and Rhizopus oligosperus.

These are the hidden architects behind a vast range of traditional eastern fermented foods, fundamentally changing ingredients like soybeans into staples such as soy sauce, miso, and the highly digestible tempeh.

Yeah, this deep dive really does highlight how much of our culinary world, our flavors and textures, is shaped by organisms we often just overlook, or maybe even instinctively distrust because they're molds or yeasts.

We just take them for granted.

And this really raises an important, maybe provocative thought for the future.

We've honestly barely scratched the surface of systematically using fungi to, say, pre -digest and add flavor to nutritious, but perhaps currently indigestible or just plain tasteless food sources.

I mean, imagine the possibilities.

Think about new foods, new flavors, maybe even more sustainable protein sources that fungi could help unlock for us in the future, especially as our global population grows and our resources perhaps become more strained.

There's huge potential there.

That's a fantastic point to end on.

It's crystal clear that these microscopic helpers are far more than just incidental ingredients.

They are truly active dynamic partners in creating the foods we enjoy every day, and they'll undoubtedly continue to shape our culinary future.

Thank you so much for joining us on this fascinating deep dive into the hidden world of fungi and food processing based on chapter 19 of Kendrick the Fifth Kingdom.

We really hope this has given you a newfound appreciation for the microbial magic happening on your plate or in your glass.

Keep exploring, keep asking questions, and definitely keep your curiosity live.

From the entire Last Minute Lecture team, thank you for listening.