Name: Why yeast extract is in tons of foods (and why it's delicious)
Uploaded: 2024-05-03T15:44:21.000Z
Duration: 12 min 37 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Yeast tastes good. And no, I'm not talking about all the wonderful foods that yeast ferment

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

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

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,

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

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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

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

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