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All cooking is science: we use chemistry and physics to steam, fry, bake, or microwave almost all of our meals. However, there are some cooking methods that delve into even deeper and stranger scientific territory.

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Sources:
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http://www.nature.com/articles/srep00196
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http://sciencemeetsfood.org/magicalmaltodextrin/
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 Introduction(0:00)


If you've ever been to a fancy restaurant or watched some TV cooking competitions, you've probably heard lots of people describe cooking as an art. But it's also a science. We rely on some chemistry and physics to steam, fry, bake or microwave our meals. Some chefs have even used their knowledge of food science to develop new creative cooking techniques, a discipline sometimes called molecular gastronomy. 

So, here are nine ways to prepare food that transform your kitchen into a laboratory.

 Food Pairing(0:34)


There are some combinations of food that are a match made in heaven; peanut-butter and jelly, bacon and eggs, grilled cheese and tomato soup, or white chocolate and caviar... apparently that's a thing. At least according to food pairing, which is a science-based method to match foods by their molecular components. 

When you eat something, chemical compounds stimulate receptors on your taste buds, which send taste information to your brain. But the flavor of a food is mostly dependent on smell, aroma compounds that stimulate olfactory receptors in your nose. When you combine foods that share the same aroma compounds they'll trigger the some olfactory receptors and complement each other. 

To find these matching ingredients food pairing involves gas chromatography coupled mass spectrometry, or GC-MS. First scientists vaporize a food sample to separate its chemical components, then they measure those components by mass, which allows them to identify which ones are responsible for flavor. Using all these data and computer algorithms, chefs can pair up ingredients that have similar aroma compounds. 

Even though white chocolate and caviar seems like a weird combo, they share several flavor compounds, including trimethylamine, which actually has a fishy odor. They work together just like pineapple and blue cheese or oysters and passion fruit. So if you follow your nose  maybe you'll find a new weird, hopefully delicious, food combination.  

Now, methylcellulose is a compound with a backward- sounding property. It can make some foods melt when they're cold and become solid when they're hot. Not rock solid, but more like a firm gelatin. It's synthesized from cellulose, which is the chain of sugar molecules that gives plants some structure. Basically, the hydrogen atoms on the hydroxyl group sticking out from the sugars are swapped out for methyl groups. This chemical change makes methylcellulose a hydrocolloid, which means when it's mixed with hot liquid water, around 50 to 70 degrees Celsius, it forms a gel. A gel just means that the carbohydrate molecules get dispersed in the water and form a tangled network instead of dissolving completely, and what's unique about a methylcellulose gel is that it melts into a liquid as it gets colder. This thermoreversible property lets chefs make food like hot ice cream, which keeps its creamy shape only while it's warm. Methylcellulose can also be used as a thickening agent in other recipes like whipped foams or meringues if you let the water evaporate out of it. So this gel lets you get creative with recipes and that's pretty cool. Or should I say hot?

Speaking of cool, liquid nitrogen is used to freeze foods really quickly, also known as flash freezing. That's because nitrogen exists as a liquid at very low temperatures, like, below -195 degrees Celsius or so. With traditional freezing methods, it takes a while for the liquid water molecules to turn into a solid, slowly growing into big ice crystals, but liquid nitrogen is so cold that dipping something into it makes the water molecules change states much more quickly and form smaller ice crystals. Ice cream can have a grainy texture if the milk mixture isn't frozen fast enough, so ice cream made with liquid nitrogen ends up being super smooth and creamy. Flash freezing is also great for preserving foods, because big ice crystals can destroy the structure of cells, which can change the texture and the flavor. It can even freeze oils or alcohols, which have really low freezing points, or make squishy foods brittle to create frozen fruit powders.  

But a lot of cooking is about heat, like the sous vide method, a French term that means under vacuum. It's a way to heat food evenly using vacuum sealed packaging and a water bath. When you heat food up, it destroys some of the cellular structures and causes chemical reactions, which can change the way it looks and tastes. You want this change to an extent, because that's the point of cooking food, but temperature control can make all the difference between a nicely seared steak and the outside being burnt to a crisp while the inside is still cold. The sous vide method gives you really precise temperature control because you vacuum-seal food in a bag, then submerge it in water that's heated to the temperature you want. It's not really possible to overcook your food this way. Plus, the vacuum seal prevents oxidation reactions with the air that can change the flavor compounds and it prevents moisture loss due to evaporation. This gives a more even cook and preserves the texture and the flavor, resulting in a perfectly juicy and tender steak every single time. Vive le sous vide!

Spherification is kind of what it sounds like, turning a liquid into squishy gel spheres. The process involves sodium alginate, a chain of sugars that gives seaweed its flexibility, because it's also a hydrocolloid and can form gels when it's dispersed in water. When flavored liquid with sodium alginate is dropped into a calcium salt bath, it can make gelatinous spheres. The calcium and sodium ions essentially swap places and the calcium can make cross-links of two bonds between the alginate molecules instead of sodium's single bond. This cross-linking binds the sugar chains together to form a stable gel sphere around the flavored liquid. Depending on the length of time, the gelification of the balls can vary. A shorter time and the spheres will have a thin layer of gel on the outside with a juicy liquid center, like fake caviar or popping boba. Waiting longer results in a thicker more solid gel sphere. So the next time you're at a fancy restaurant, don't assume those tiny balls are salty fish eggs; it could be spherified mint mojito.

But what if you wanna stick solids together? Well, you can use transglutaminase which is also unappetizingly called meat glue. It's not actually glue, though. It's a natural enzyme that helps proteins bind together, like to help form blood clots or keep skin cells nice and taut. In the culinary arts, transglutaminase used to be isolated from cow or pig blood, but now its mostly made using engineered bacteria, and it's typically mixed with some other ingredients like gelatin to enhance its binding properties. When a transglutaminase enzyme is set into action, it can work its binding magic on any protein, so it can be used to make any mixture of meats, like meat noodles, sausage without casing, or bacon-covered scallops without having to use skewers to hold it all together. Even though meat glue sounds not so tasty, just think of the awesome ability to mix and match meats.

Cotton candy, also known as candy floss, has one main ingredient: sugar. Sometimes there's food coloring and flavoring thrown in there too. Table sugar, which is the chemical sucrose naturally exists in a granulated crystal form. So how does it become so fluffy and cloud-like?  Well, it's not fairground magic, it's science. When sugar is poured into the center of a cotton candy machine, it's heated up near its melting point around 185 degrees Celsius, so the solid crystals of sucrose begin to break apart into individual sugar molecules and the mixture starts to liquefy into a syrup. Cotton candy machines are essentially large centrifuges. There's a center basket with small holes in it, which spins at a speed of around 60 revolutions per second. Then the melted liquid sugar is forced through the holes by outward inertial force into an outer collection basket, and this creates really thin sugar strands, around 50 micrometers in diameter, so thin that the sugars instantly cool and become solid again. Pool enough of these strands together, twirl a stick into the fluffy mess, and you get cotton candy.  

If you wanna change the form and texture of oils into fluffy powders, maltodextrin is what you're looking for. It's a carbohydrate that's synthetically derived from the starch of certain plants and has a helical structure like the amylose molecules in starch.  So it might have a light, sweet taste, but otherwise, it's essentially flavorless. The inside of the maltodextrin helix binds to hydrophobic molecules, while the outside binds to hydrophilic molecules. Because oils don't like interacting with water, they're attracted to the hydrophobic interior of the maltodextrin molecule, and they're separated from one another. That's how the maltodextrin molecules can turn any liquid oil into a light and fluffy powder. Peanut or coconut oils can make light powders to top off a dessert, or chefs can add a sprinkle of savory olive oil or bacon powder to garnish an entree, and once the powder comes into contact with the saliva in your mouth or any water, it dissolves the maltodextrin, releasing the flavorful oil molecules for your taste-buds to enjoy. 

A foam is essentially a liquid or solid with pockets of air inside, and there's a trend where chefs are making edible flavored foams. All you need is a water-based liquid, air, and a stabilizer to keep the bubbles from popping. Soy lecithin is an emulsifier, which is something that helps keep a solution of different liquids mixed. Lecithin molecules have both a hydrophobic end and a hydrophilic end, which binds different kinds of ingredients and keeps them mixed together. For example, you can mix hydrophilic sugar with hydrophobic cocoa butter and cocoa solids to make a fluffy and creamy chocolate. When this emulsified liquid is mixed with any gas like air, the soy lecithin also acts as a surfactant, lowering the surface tension of the air bubbles so they're less likely to pop. Basically, this helps keep the foam foamy, and while a bubbly foam won't be the most substantial part of your meal, it's definitely the most fun to eat.  

These food preparation methods seem like they'd only be found in a fancy restaurant, but most of them can also be done right in your home kitchen. Cooking doesn't have to be complicated if you understand the basic science behind it, and molecular gastronomy proves that science can be tied in with an art form, and a delicious one at that.  

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