Edible Science Experiments

HEAT - Much of an egg is made up of protein molecules floating around in water. Think of a protein molecule as a long strand of differently-shaped beads. Protein molecules in raw eggs are normally curled up (called globular proteins) as they float around in water. They stay in their curled up state because of weak bonds between different parts of the protein molecule. As the proteins are heated, they get all excited, start jumping around more, and the weak bonds are broken, causing the protein molecule to straighten out. As they continue to crash around, the straightened protein molecules form bonds with other protein molecules, trapping the water and forming a solid mass.

Meringue - Remember those curled up molecules? One of the big reasons they are curled up like that is that parts of the protein molecule, called amino acids, like to be near water. These amino acids are called hydrophilic. Other amino acids really don't like water, and they are called hydrophobic amino acids. My dog, Zippy, is extremely hydrophobic.

Those amino acids that are hydrophobic pack into the center of the molecule to stay away from the water. The hydrophilic amino acids are happy to stick out into the water. When air is introduced into the egg white protein by whipping it, air bubbles begin to touch the proteins. The molecules begin to uncurl, so that the hydrophobic parts can get to the air. Once unfolded, the proteins bind to each other (instead of themselves) just like when they were heated. They trap air bubbles. If you then heat the protein, the air bubbles expand, and if you're really careful, you can turn the whole thing into a solid (see HEAT above), yet fluffy mass. Why won't egg whites whip up if they get some yolk in them?

PAVLOVA A beaten egg white can foam to eight times its original volume. Soufflés, angel food cakes, and meringue all make use of the exceptional foaming powers of egg.
FLAN   A baked custard, its essential ingredients are eggs, milk, and sugar. As a custard bakes, the egg proteins form a network that traps liquid, creating a gel.

Fermentation is a chemical process cells use to produce energy. Cells use glucose to make adenosine triphosphate (more commonly known as ATP). They use the ATP to power lots of different important processes required for survival.

In this process of converting glucose to ATP for energy, some cells, like bacteria and muscle cells, produce lactic acid as a byproduct. Lactic acid is what makes yoghurt and pickles tart. When you use a lot of energy by exercising or working your muscles hard, the byproduct, lactic acid, causes that burning sensation in your muscles. Does lactic acid make my muscles sore?

When yeast use glucose to make energy, carbon dioxide and alcohol are produced as waste products. We can use these in all kinds of fun ways. If you want to make bread, the carbon dioxide produced by the yeast will make air pockets in the dough to give you fluffy bread. Most of the alcohol bakes out. You can make carbonated beverages the same way. But the longer you let the process continue, the more alcohol will be formed (until the yeast is killed off). Then you have beer and wine. How is beer made?.
Fermentation is Fun: How to Get Started with Fermented Foods at Home
How is a cow like a yoghurt maker?

MAKE YOGHURT  Bacteria make lactic acid, turning milk into yoghurt.
KIMCHI   Kimchi ferments in the vegetable's own juices. Although there are scores of varieties, kimchi is usually made with cabbage.
CEVICHE   Here's culinary proof that you don't need heat to cook fish. The citric acid in the lime juice "cooks" the tuna by changing the structure of the proteins.
BASIC SOURDOUGH STARTER   Working with starters takes practice. Many variables-for example, the amount of yeast in the air and the temperature of the room-will affect the fermentation process. It might take a few tries before you get the flavor you like.
GRAPE SOURDOUGH STARTER   The following Italian sourdough starter, or biga, uses the wild yeast naturally present in grapes. The fruit also provides the sugar on which the yeast feeds.
GARLICKY DILL PICKLES   In this recipe, you ferment cucumbers to make dill pickles. This means you'll be setting up special conditions that allow "good" bacteria to grow on your cucumbers. These bacteria do not spoil your cucumbers. Instead, they digest the cucumber's sugars and produce lactic acid, changing the vegetable's flavor and texture-and turning your cucumbers into pickles in about three weeks.

Photo by fd

Baking doesn't involve just one chemical reaction. The application of heat to food ingredients has all kinds of amazing effects. It can unwind proteins, cause ingredients to produce gas, form new chemicals......Let's have a look at some of the things that happen when you put something in the oven.

THE CHEMISTRY OF POUNDCAKE 101   Discover the internal working of cake baking.

A CHEMIST'S RECIPE FOR CHOCOLATE CHIP COOKIES  Originally appeared in Chemical & Engineering News (C&EN, Jun 19, 1995, p. 100).  

FLAN   A baked custard, its essential ingredients are eggs, milk, and sugar. As a custard bakes, the egg proteins form a network that traps liquid, creating a gel.

Photo by livelaughlove

Look at the picture of the lemon on the right. Keep looking for about ten seconds. Did your tongue react? It's all about taste.

Science has identified at least six tastes that the human tongue can recognize: sweet, sour, salty, bitter, fat and umami. The word "umumi" means delicious in Japanese, and it's the way our tongue generally recognizes protein. Umami is a savory taste, often associated with meat.

With only six tastes, how do we get the broad selection of tastes that we know our food to have? Good question. Let's look at some of the experiments you can do to find out.

MOCK APPLE PIE   When flavors come together, they often meld and blend into something that may be surprisingly different from the original ingredients.
THE COLOR OF FLAVOR   Since we can only taste four different true "tastes", it is actually smell that lets us experience the complex, mouth watering flavors we associate with our favorite foods.
QUININE COVERUP   This experiment will show you how easy it is to tone down a bitter flavor.
ORANGES: SWEETER AT ONE END   Different parts of the same fruit can taste different.  Is this hypothesis true? To find out, perform the following experiment.

PREVENTING AN APPLE FROM TURNING BROWN   How can you prevent a cut apple from turning brown?
MAKE YOUR OWN ORANCE SODA   Hypothesis:  Adding orange juice to baking soda will make orange soda.

MONSTER MARSHMALLOWS   In the microwave, an ordinary marshmallow will puff up until it's enormous!
CHOCOLATE LEAVES   A yummy experiment about solids and liquids and heat.
LIGHTNING IN YOUR MOUTH   Crunching on a wintergreen LifeSaver® makes a miniature lightning storm in your mouth.
GETTING JUICE FROM A LEMON   There is an easy way to get juice out of a lemon.
THE CAT'S MEOW   Oil causes food color to circulate in milk making swirls of color.
SPLIT THE SMARTIE  Edible dye chromatography.
SNAP CRACKLE JUMP   Rice Krispies seem to jump and float from a table top to an overlying plate of glass or plexiglass rubbed with a wool sweater to generate a net negative charge.
GELATINOUS VECTOR COMPONENTS   This experiment demonstrates the x and y components of a vector force using Jello.
FRACTURES IN CHEESE   Learn how fractures grow by pulling on a piece of cheese.
GRAHAM CRACKER EARTHQUAKE   The experiment demonstrates the forces that create earthquakes. It also shows the tension that can build up before a quake and the resultant debris created along a fault.
TURKEY DAY CHEMISTRY IN THE KITCHEN   Whip up a whiz-bang holiday feast using lab-tested principles of chemistry and thermodynamics. Sound like a job best left to the pros? Not so!