David Olson
speaker
61 appearances
9 recordings
1 series
first heard Nov 2024
last heard Jun 2025
David Olson’s voice in public audio — every appearance, attributed to the second.
Trend
recordings per month · last 12 monthsNo recordings in the last 12 months.Older appearances are listed below; set an alert to hear about the next one.
Appearances
They are high up in the troposphere, you know, floating on moats of dust. There are microbes that have been found in like gold mines in South Africa. And they're probably also on the food itself, whether that's flour, whether that's a cabbage on any given food.
They are there as a minority population with a lot of other bacteria, soil bacteria, microbes, you know, microbes that might be found in feces or manure from the actual field itself.
And it's your job to suppress those microbes immediately by using things like oxygen or an absence of oxygen, more specifically, or salt to make sure that they are tamped down and you give center stage to those lactic acid bacteria.
They will start to... release enzymes into their environment that will break up the carbohydrates in the plant cells themselves and allow them to digest these sugars. Carbohydrates and starch and lots of plant fibers are just stitched together chains of simple sugar molecules like glucose. And so...
In the great tree of life, lots of organisms have devised enzymes that snip those daisy chains into their constituent molecules.
Then they can grab an easily handable portion of chemical energy in the form of sugar, eat it, and through the process of fermentation, which going back to the textbook microbiology definition, is the metabolism in the absence of oxygen of a sugar molecule into either ethanol or lactic acid.
Yeah. And then when it harvests the chemical energy, energy for its own purposes, what's left over is lact gas.
That's the byproduct. That's like microbial poop, basically.
The good thing is that humans... seem to like the flavor of lactic acid. And even when a food source gets pretty acidic, and we're talking about below 4.5 on the pH scale, like we find it pretty palatable and it's something that we enjoy eating. So they're in the Venn diagram of foods that microbes like and foods that humans like. There's a lot of overlap there.
And when they get the party down in our food supply, we seem to like what they do. And so this is, in every way, shape, and form, a symbiotic relationship.
And how is it the same? It is, it is... It is different, but it is the same. We're going to go back down the phylogenetic tree of life to the origin of eukaryotes. So there's filamentous fungi floating in the ocean. And then... One of these multicellular organisms was like, I'm going to revert back to being a unicellular, just me and my kids floating as little dots in the sea, microbes.
It's kind of like whales going back into the ocean. Wow. Fungi evolved from single-celled organisms and yeast, nothing truly devolves, but yeast went back from being multicellular organisms to adopting a single-celled lifestyle once again. Wow. Which is interesting.
Yeast are cool critters. They are eukaryotes like us, which means they have a cell nucleus. There are thousands of varieties. And all yeast really means is single-celled fungi. So we think of yeast as like, oh, yeast is the thing that is in bread. But there are like thousands and thousands of varieties of yeast. So many different types and clades. And so they do a lot of the same things.
If we're baking sourdough bread, They use the action of some of those same lact gas bacteria that we just talked about. They'll take sugar and they will produce ethanol, yes, but they'll also produce carbon dioxide.
And that carbon dioxide production is what helps to make these little pockets of gas formation inside of a bread dough.
Historically? You can't keep microbes out of your food if you try. This is something we can't forget, right?
Like, just the history of humanity. You want to talk, like, plagues and infestations and disease. Like, humans have had a rough go of trying to keep microbes out of ourselves, right? Our food was no exception. So...
the sorts of kind of culinary tricks that probably primarily many women working in kitchens, grandmothers and mothers and sisters and daughters tinkering, being like, oh, this worked and it worked really well. I should keep doing that because this is lasted or it tastes good or it keeps well.
These kind of happy accidents have like accrued and accumulated over thousands of generations to be these entrenched kind of cultural bodies of knowledge that we understand as fermentation. It really is this like falling together. It really is this kind of, it is this kind of beautiful symbiosis. It's like, how does symbiosis arise in nature in any way, shape or form?
It's an accident that works so well that the two parties become bound to each other. whether those are like cleaning fish on a whale shark or, you know, ox peckers on a hippo. Like it works to the benefit of both parties. And that's exactly what has happened with humans and the microbes that we use in fermented foods.
Showing 41–60 of 61 · page 3 of 4
← Previous
Next →