Cooking 101: Food Science Basics

July 31, 2008

This post is part of a series called Cooking 101, which introduces the basics of cooking. The series follows the book Culinary Fundamentals, with supplements from The Professional Chef by the Culinary Institute of America. Check out the previous posts here.

Editor’s Note:  I have added The Professional Chef (recommended by ntsc) as one of the books that I’ll be using in this series.  In some areas it seems more thorough, which will be helpful on complicated subjects.  On other subjects Culinary Fundamentals has better explanations for the beginner, so I’ll use both.  I will stick with the layout and order of Culinary Fundamentals, but The Professional Chef will help round out the information I have.

Unit 4: Food Science Basics

Food science is an interesting topic for me, and I imagine that the more science I understand behind cooking, the greater freedom I’ll having when creating and adapting dishes without recipes. Can you learn to cook without knowing the science behind everything? Sure, but learning it can only help.

Food science is a complex and massive subject. If you’ve ever taken a look at Harold McGee’s On Food and Cooking, you’ll find it absolutely packed with information on the science behind cooking. I’ve done plenty of science posts in the past and intend to continue them, so this will be an overview on the basics of foods, heat transfer and its effects, and emulsions.

Foods

Carbohydrates

Carbohydrates come in two forms: sugars and starches. Simple sugars are soluble and sweeten foods. They also attract water, which means sugar can be used to help preserve things like fruit. Starches are complex carbohydrates and are not soluble. When cooked in water, though, starches loosen and will take it in, softening their texture. Carbohydrates are found abundantly in breads, pasta, fruits, vegetables and grains.

Proteins

Proteins, as described in the book, start out shaped like long coils. But when heat, salt or acid is applied, they uncoil, or denature, and form new bonds. These bonds can be loose or tight, but the tighter bonds are what you see when you cook a piece of meat to well done. Other proteins can behave differently, although I think they all follow the same basic principles. Bread protein, or gluten, forms long strands when kneaded and egg proteins solidify when cooked.

One interesting fact about proteins is that they give off water as tighter bonds form, even when cooked in a liquid. This is the reason books tell you to let meat rest for a few minutes when its done cooking - the proteins will reabsorb some liquid, resulting in a moister product. Proteins are found in meat, eggs, dairy, legumes and nuts.

Fats

Fats have all sorts of uses in cooking. They can keep foods from sticking in pans, dry them out to create a crunchy crust, or dissolve and create various flavors. The book also says that it can tenderize foods by spreading through them and preventing large groups of proteins or carbohydrates from coming together.

Water

I don’t normally think of how important a role water plays in cooking, but it is everywhere and knowing its properties can be useful. As far as cooking techniques that use water, you have boiling, poaching, simmering and steaming. In addition, dehydrating foods can help preserve them (like curing with salt), while rehydrating foods is sometimes needed to make them edible (like dry pasta). Finally, remember that it boils at 212° F (100° C) and freezes at 32° F (0° C).

Acids and Bases

Adding acids and bases can have significant effects on how food cooks. The book gives an example of green beans, where salting the water will keep them green and the pH stays close to neutral. Add an acid though, and the color leaches out and you’ll have dull beans. Add a base and you get bright green beans, but a mushy texture. Sound familiar? Of course, I wrote about this effect earlier here. Documenting all the effects is not possible here, but I’ll try to point out how acids and bases affect cooking as we come across it in the future.

Heat Transfer

There are numerous ways to transfer heat to foods and each will have different effects. Conduction is direct contact between molecules that transfers heat. Think cooking in a pan or the molecules of air around a loaf of bread in the oven - direct contact.

Convection is “the transfer of heat through moving gases or liquids.” This happens when you cook something in boiling water or use a convection oven, which keeps the air moving. With convection, the liquid or gas that is close to the heat source heats up quickly and rises, while the cooler liquid away from the heat falls, creating a current of movement. Convection can be useful when making something like a stock because the moving liquid brings impurities to the surface.

Radiation uses electromagnetic energy to heat the outside of foods. Infrared radiation comes out of all sorts of heat sources, including grills and your broiler. The infrared radiation will heat the cookware or outside of the food, then conduction will carry the heat inward and cook it through.

Microwave radiation comes from your microwave. Shocking, I know. I didn’t know this, but apparently foods high in moisture, sugar or fats are the best for a microwave. Just remember not to use metal in it.

Finally, induction cook tops use magnetic currents to heat up pans, but leave the food surface dry and respond to temperature changes very quickly. I don’t really know much about these sorts of stoves, but they sound pretty cool. Does anyone have one?

Cooking

There are six basic principles for food science: caramelization (here), Maillard reaction (here), gelatinization (below), denaturation (above), coagulation (no one mentions this further), and emulsification (below).

Culinary Fundamentals lists three main affects that cooking can have on food.  First, cooking can either dehydrate or rehydrate a food. Second, heat can create caramelization or the Maillard reaction, also known as browning and discussed previously here. Browning is very important in a lot of cooking and the science behind it is pretty interesting.

Gelatinization is something that I have not covered. Gelatinization occurs when starchy foods are cooked with water. The starch loosens, absorbs some water, and eventually can soften enough to lose its shape. Then, these starch molecules mix with whatever else you are cooking but trap water molecules, thickening the sauce/dish. Apparently root-based starches thicken at lower temperatures than cereal based starches.

Emulsions

An emulsion is the suspension of one ingredient evenly throughout another. A common emulsion is a vinaigrette, where oil and water are combined. Usually one ingredient is broken up into very small pieces so it can be mixed with the other. Interestingly, both mayonnaise and forcemeat (like sausage) are emulsions.

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