for us, like bread and beer. I mean the yeasties themselves. They taste good. Boil a packet

of dry yeast in a little bit of water to kill the yeast, maybe put in a little pinch of

salt, and taste the resulting broth. You know what that tastes like? It tastes like mushroom

stock, which I suppose should not have surprised me as much as it did, considering that mushrooms

and yeast are the same basic thing.

They're both edible funguses, and so they taste a lot alike. They both taste meaty.

As we have discussed in previous videos, the fungal kingdom is arguably a lot closer to

the animal kingdom than it is to the plant kingdom. And fungi have a lot of the same

kinds of things in their bodies as we animals do, such as the amino acids that taste umami-y.

We need to eat protein to live, and protein sources that are good for us are likely to

contain glutamic acids and some related organic compounds. And therefore we are evolved to

find those compounds very, very tasty. That's umami. That's the savory, meaty sensation

we get on our tongue. And yeast have a lot of it.

Again, maybe you already knew this, but I was completely floored by the taste of a boiled

packet of bread yeast. That is good soup. And now I understand why so many processed

foods have yeast extract on the ingredients. Check out the ingredients on nearly any dried

soup product — Cup Noodles, or this one, this Lipton noodle soup. Look on the back

and you will see yeast listed on the ingredients. Or more specifically, a yeast extract that

has been juiced out of the yeast. That's it right there — yeast extract that I juiced

out myself. I'll show you how I did that in just a minute. Boil that yeast juice down

and mix it with some reduced vegetable broth, and you'd basically have Marmite, this gooey

brown stuff the Brits like to spread on toast. The Aussies have a similar condiment they

love called Vegemite.

And if you taste this stuff, it tastes a lot like that reduced yeast extract, because that

is in there. It also tastes like celery and some of the other vegetables that they put

in here — basically concentrated vegetable stock is in here as well. There's also a third

distinct and very strong taste in here, and that is the taste of beer. Indeed, the story

of yeast extract begins with beer. When you brew beer, there is a ton of leftover yeast

— way more yeast than you would ever need to brew your next batch. And probably even

more than the bakery down the street would need to rise their bread. Historically, spent

brewer's yeast was regarded as a waste product.

Then came Marmite, a company founded in 1902 in the English beer-brewing Mecca of Burton-on-Trent.

According to the company's own history of themselves, the founders based their concept

on research done by the German food scientist Justus von Liebig. Liebig is also the guy

whose work led to the dubious chef wisdom that searing meat seals in the juices, which

it doesn't. In his own lifetime, Liebig was much more famous for inventing a liquid meat

extract that he said could replace a solid food diet, which it couldn't. But it did taste

really good. And Liebig's product eventually became the English stock cube maker, OXO.

Liebig also did work on yeast and sometime in the 19th century, he is purported to have

done basically what I did here in my kitchen.

I took a whole jar of active dry bread yeast from the grocery store and I dumped that into

water. Liebig used some spent yeast from a brewer, which probably would've come to him

already suspended in some amount of water. In his experiments, Liebig heated this solution

to a balmy temperature that activated enzymes within the yeast cells. I don't know what

exact temperature he used, but in 2007 these Turkish researchers determined that the optimal

temperature for making yeast extract is 50ºC, 122ºF. So that's what I used. Unfortunately

for me though, 50ºC is kind of just below the minimum temperature that you can reliably

hold in a domestic oven or on a gas stovetop. You're probably going to get a temperature

a little higher than that. And at that point, you risk denaturing the enzymes in the yeast

that we need for this process. So — electric heating pad.

It took me a while to find the right setting and the right way to wrap this around the

bowl to get my target temperature. And even when I did, the temperature suddenly shot

up when my dried yeast woke up and they started metabolizing the energy stores in their little

unicellular bodies. That is their body heat, thermogenesis. I had to rip the heating pad

off so that my solution did not overheat, but then the yeast calmed down after a while,

because I didn't give them any food to eat in that water. So they just kind of stopped

metabolizing, my temperature plummeted. So I had to put the heating pad back on. And

when I did that, I was not able to get the temperature up high enough. This just wasn't

hot enough. I was only able to hold my bowl at like 35ºC for a day. And basically nothing

happened. This is not yeast extract. It's just warm yeast in warm water. It tastes okay,

but not super strong.

And you generally don't want to eat very, very much live yeast. Speaking of microorganisms

in the gut, the sponsor of today's video is Ombre Lab. Let me thank them for a sec. The

science on gut health is really still emerging, but basically every researcher I talk to about

nutrition is very excited about what we're learning. About how the particular mixture

of bacteria living in our digestive systems affects our metabolism, our mood, basically

everything about our health and how we feel. A foolproof test kit from Ombre Lab offers

you a look inside your own microbiome. You collect a tiny sample at home, you send it

in and here are my results.

Based on the limited, but really promising research that we have so far Ombre is able

to make recommendations as to how I might boost beneficial organisms in my gut. And

they're able to tell me what these buggies might be able to do for me. Looks like I could

use more Roseburia. There's mouth studies showing that one as helping with weight loss

and inflammatory diseases. Based on your results, Ombre will give you diet recommendations.

And if you want, they'll offer you custom probiotics you could take to encourage good

bacteria. Use my link in the description and you'll get 30 bucks off your test kit. $30

off at tryombre.com/adam. That's in the description. Thank you Ombre Lab.

But anyway, yeah, I could not get enough heat to squeeze the juice out of my yeast. So I

went out and I bought a much bigger heating pad. I tied it snug around the bowl with a

cute little scarf and there, a perfect 50ºC. I held it there for 24 hours, which the aforementioned

Turkish researchers found as the optimal time to achieve what Justus von Liebig achieved

before me, and that is yeast autolysis. It's funny — we just talked about autolysis last

week when we were talking about gluten proteins in flour. Autolysis basically means cellular

self-destruction. At this temperature in water, enzymes within the yeast cells break down

their own cell walls, causing their little yeasty guts to spill out into the solution

and further reactions break down their proteins into more of the tasty umami-y amino acids

and such that we like to eat.

That semi-clear liquid is the lysate — the extracted cellular guts dissolved in water.

I should have just siphoned it off the top because my filter here did not do such a great

job of removing the solids that had settled on the bottom. Those solids are what's left

of the yeast cell walls. That's what's in the slurry there: cell wall debris. It's often

filtered out with a centrifuge at yeast extract factories. I suppose it dilutes the flavor

of the extract, but I will say it actually makes kind of a nice thickener. Here's some

homemade yeast extract that I did not filter at all. I boiled it down. I put in some onion

powder and some celery seeds to mimic the vegetable flavors they add to Marmite. And

that's honestly some good vegan gravy right there. The cell wall debris gives it a really

creamy texture.

I will say that creamy texture could be due in part to an additive that they put in grocery

store bread yeast like this. It's called sorbitan monostearate. It's an emulsifier. They put

it in there to keep the yeast from getting too dry when they're in storage. And also

it helps the yeast to rehydrate inside the dough. Seems possible to me that this additive

is forming a water-and-oil emulsion here in this solution with the lipids naturally present

in the yeast. And that might be contributing to that creamy texture. And it also might

be making my extract harder to filter. I basically have yeasty mayonnaise gumming up the works.

But for what it's worth, I also did a test with an organic yeast packet that does not

have any emulsifier inside it. And when I boiled that down to a paste, it still had

a somewhat creamy texture. So, who knows?

All I know is, according to the story, Justus von Liebig filtered the solids out of his

lysate, he boiled it down to a glaze and he was struck by how closely the taste of that

resembled a reduced animal stock. That's basically vegan demi-glacé. Quite tasty. So based on

Liebig's experiments, these folks built a factory in Burton-on-Trent, and they tried

to work out a process for converting cheap, ubiquitous spent brewers yeast into a food

fit for human consumption. One problem they ran into is that brewers yeast is covered

in bitter residues from the hops. You have to de-bitter the yeast. And even after they

do, Marmite is still a little bitter. I'm told most people who eat this on toast do

a very thin layer, and then they cut it with some butter. I do think that's quite tasty,

but it does still very much taste like beer.

Whereas the extract that I made from bread yeast does not. Nor does this so-called nutritional

yeast taste like beer. Not at all. This company says they grow their own yeast in a molasses

solution rather than getting it from brewers, so there's no hops residue, there's no grain

residues. But it's not a yeast extract. It's whole yeast, baked until they die and they

form little flakes that you can use as a seasoning. It's quite tasty, but not nearly as strong

as the extract — because of all of the cell wall debris that's still in there, I assume.

I had hoped to be able to give you a practical recipe for homemade yeast extract. There are

a lot of ones on the internet and they all have big problems in my opinion, and I did

not do any better. One problem is that this bottle of yeast is $6 and you want to see

how much extract I was able to get out of it? This much. That's what I got. Not very

cost-effective. I also do worry about the sorbitan monostearate content in here, the

emulsifier. Every food safety agency on earth considers that stuff perfectly safe in the

amounts that you would eat if you were using a little dry yeast to bake a whole loaf of

bread. I have no idea how much of it you would end up eating in a concentrated yeast extract.

And I have no idea if that amount would be safe. No idea.

I figured I could remedy both of these problems by simply growing my own yeast at home from

one little starter packet. I put one little packet into about a gallon of sugar water,

and I watched it bubble for a few days before I realized that I'm basically making rum here.

This is now a terrible-tasting alcoholic beverage that you could distill into rum. The thing

about making alcoholic beverages, it's actually kind of tricky to do well. You could get all

kinds of contaminants in here. This had a pretty funky smell. And the bread yeast seemed

to shut down long before they'd fermented all of the expensive sugar I gave them. There's

not that many yeasties in there, and I was totally unable to filter them out of my stanky

bathtub hooch. Maybe you can figure out a good way to grow yeast at home for extract.

Or maybe you could get it from a friend who home-brews. The problem is then you would

have to de-bitter it. And apparently, the processes that they use for de-bittering yeast

at the factory are pretty industrial, pretty intense, not easy to replicate at home.

So maybe just buy yeast extract instead. Here in the States, I get Marmite at the grocery

store, Publix, which has a British import section, #NotAnAd. This is the same import

section that has these OXO cubes that are nearly solid yeast extract. There's no animal

product at all in these. People originally considered yeast extract to be an adulterant

in stock cubes — a cheap imitation of real meat. But I think this stuff is great in its

own right and I'm not even a vegan. If you are a vegan, definitely check out yeast extract.

It's rich in the B vitamins that can be tough to get if you don't eat any animal products.

Indeed, researchers like this American chemist in 1916 came to understand the necessity of

B vitamins in part through their experiments with yeast. They fed pigeons a diet of only

plain white rice and the birds got really weak and wobbly. Same thing happens to humans.

We call the resulting disease beriberi. The researchers gave those pigeons white rice

fortified with yeast extract and the pigeons got better, because B vitamins. Yeast — one

of humanity's best friends.