[♪ INTRO] Mushrooms are really different from all
the other produce in your fridge. For starters, they aren’t even plants, biologically speaking.
And what sets them apart from the rest of your fruits and veggies also affects how they hold up
to cooking. A mushroom-based dish can make even the most novice chef look like a culinary genius
because you can’t really overcook a mushroom, no matter how you try. In an experiment to see how
different kinds of foods change texture as they cook, America’s Test Kitchen compared zucchini,
beef tenderloin, and portobello mushrooms' ability to stand up to the heat. After five
minutes of steaming, all three were very similar in texture and all were deemed tender by taste
testers. But that quickly changed after just five more minutes. The beef started to toughen
up and the zucchini got mushy, yet the mushroom remained perfectly tender. And after 40 minutes of
steaming, the mushroom reigned supreme, retaining roughly the same texture and tenderness rating,
whereas the beef had turned to leather and the zucchini to goo. So why did these three foods
react so differently to long-term cooking? The science behind overcooking boils down to the
food item’s biology. Let’s start with meat. We cook meat in order to make it safe to eat,
because the heat kills off any unsafe bacteria that are hanging around in there. Cooking also
has the added benefit of making meat both tender and delicious, as long as you don’t
overdo it. Anyone who’s overcooked a steak knows that it only takes a few minutes to take
it from delicious to practically inedible. Nwo structurally, meat is made up of mostly proteins,
long chains of amino acids that are all folded up due to strong hydrogen bonds connecting the chains
to themselves. When you add heat, it breaks these bonds, causing them to unfold through a process
called denaturing. Applying the right amount of heat creates very tender meat, because of
what happens as the proteins denature. Take the proteins myosin and actin, for example. These are
proteins responsible for trapping water in the meat. And they are some of the first to denature
when meat is heated. As they change shape, they release some of that water they’re hanging onto,
which makes the meat juicier. And some cuts of raw meat are tough due to collagen fibers, which help
provide structure, and connect bits of tissue to each other. As the temperature of the meat rises,
that collagen breaks down, too. And as it does, it turns into gelatin, which gives the meat a tender,
melt-in-the-mouth, falling-off-the-bone kind of texture. Gelatin is what sets up your Jellos and
mousse-like desserts, because when it cools down its solid but jiggly. But when it’s warm, it’s
a liquid, so it contributes to that juiciness in cooked meats. So when it comes to overcooked meat,
the problem essentially lies in having too much of a good thing. The myosin and actin proteins
denature fully, and release all the water they were hanging on to, which leaves behind only
tough proteins. And eventually the meat has a hard time hanging onto that liquid gelatin, so it all
seeps out of the meat. So that’s the chemistry of overcooking a piece of meat. But the story of
overcooked veggies, just like their eventual texture, couldn’t be more different. Plant
matter is made up of mostly polysaccharides, like starches and cellulose, which gives those leafy
greens or celery stalks their rigid structure. Polysaccharides are polymers that are made up of
hundreds or thousands of glucose molecules bound together in long chains. Hydrogen bonds then
make these chains into bundles, forming fibers. And it’s these fibers that give polysaccharides
their strength and stability. But when you add heat to polysaccharides like those starches and
cellulose fibers, the bonds weaken and break, which releases all that glucose. This is why
carrots are crunchy when they’re raw, and roasting them makes them softer, but also sweeter. And if
you overdo it on roasting those carrots, too much of that cellulose breaks down. Since that’s the
main structural component of the carrot, there’s basically nothing left to hold it all together,
so you end up with carrot mush. Now, mushrooms are neither meat nor vegetable, even though they
usually get lumped in with the vegetable crew when they’re on your plate. Mushrooms are fungi,
and they’re more closely related to you than they are to anything else in the produce section. The
part of the mushroom that you eat is the fruiting body of a much larger organism referred to as
mycelium, and that fruiting body is what fungi use to reproduce by spreading spores. But,
fungi don’t rely solely on proteins to retain their rigid structure. Much like plants,
fungi use a polymer for their structure. But it isn’t starch or cellulose. Instead, they
use a much sturdier polymer called chitin. You may have heard of chitin, and you’ve almost definitely
seen it before. Chitin is used by creatures like shellfish and insects to build their exoskeletons,
and it’s much more heat stable than cellulose. While cellulose breaks down at lower temperatures,
chitin won’t break down until it hits almost 400 degree celsius, which is higher than most of us
crank the heat during cooking anyway. So that rigid chitin is the key to mushrooms maintaining
their firmness when being cooked. Any changes in texture you might observe when mushrooms are
cooked is due to their high water content. Cooking causes them to release that extra water they were
hanging on to. But, try as you might, you can’t ruin the texture of a mushroom with heat, even
if you misread the recipe and cook them for 100 minutes instead of 10. They’re in a class of their
own, both in a biological and culinary context. Their unique composition sets them apart from
other veggies, making cooking seem easy while at the same time impressing your dinner guests! So,
if you’re just starting out on your culinary adventures, consider mushrooms as some of the
first foods you try your hand at cooking. But be warned: this does not mean that you can’t burn.
This video was made possible thanks to our supporters on Patreon. It takes a lot of people
to make these videos possible, and we couldn’t do it without the support of our patrons. If
you’d like to become a patron yourself, you can go to Patreon.com/SciShow to join, and as always,
thanks for watching. [♪ OUTRO]