[♪ 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]