Combined with last month’s article from Chef Weiner on the basic science behind critical processes in the kitchen that all culinary students should understand, the following 10 precepts truly sum up any student’s “necessary science.”
By Adam Weiner, CFSE
Two months ago I raised the debate about teaching cooking science to students. Last month I wrote part one of what I personally think are the principles of science that should be taught to beginning culinary students. Here is part two:
1. Animal proteins, such as beef, seafood, poultry and pork, are each made up of a complicated structure of proteins, fats, carbohydrates and water. Each of these proteins, fats, etc., is affected differently by heat in cooking. The amount of each item (for example, the amount of protein and the amount of fat) will affect the time, temperature and cooking principle used to cook each food. A piece of beef with a lot of connective tissue will generally need a moist cooking technique such as braising.
2. The more you break up the membrane between garlic or onion cells, the stronger the garlic or onion flavor. Dicing onions or garlic finely causes great disruption in the cell membranes, which results in a lot of “flavor.” Cooking onions or garlic with little or no breaking of the cell structure yields a milder flavor.
3. Water, and every other liquid, has a specific boiling point. What determines the boiling point is what is in the liquid and what is the atmospheric pressure. Once that liquid reaches its boiling point, it can’t get any hotter even if more heat is applied. Simply adding a lid to the pot or pan won’t increase the temperature. Using a pressure cooker (extremely rare in commercial kitchens) will increase the atmospheric pressure, so the liquid can get hotter than the normal boiling point—which is why food cooks in less time.
4. All fats are made up of fatty acids and glycerol. The properties of the different types of fats are determined by the particular characteristics of the fatty acids that join the glycerol molecule. In general, at room temperature, the fats from animals are usually solid, while the fats from plants (such as olive oil) are usually liquid. Note that vegetable oil can be chemically modified to be made into shortening and margarine. Fats include saturated fats, unsaturated fats and polyunsaturated fats. These different fats not only have different health aspects (as we are reminded almost daily), but also have different cooking characteristics.
5. Of course, we all know that oil and water don’t mix. However, emulsifiers can be used to hold oil and water in a chemical bond. When you use an emulsifier to hold oil and water together, you create an emulsion. Emulsions can either be short-lived or long-lived. Mayonnaise does not separate easily back into oil and water, but a vinaigrette does. Egg yolks are an outstanding emulsifier, which is one of the reasons they are so useful in baking.
6. Bacteria, molds and yeasts are all around us all of the time. Sometimes they are good, such as the yeast used to make bread. Sometimes they are bad, such as E-coli. Knowing how to control the good and the bad is important in the science of cooking. For example, sourdough starters make great artisan breads. Salmonella can kill people if food-safety rules aren’t followed.
7. Baking soda is a leavening agent, which means that if added to the right type of batter (which usually contains something acidic like yogurt, sour cream, buttermilk, lemon or honey), the batter will rise. If there isn’t enough acid in the batter, the batter will not rise and the product will have a bitter chemical taste because the baking soda did not break down when mixed with the batter. When using baking soda it is important to use the correct amount. Too much yields a bitter taste and too light will not cause enough bubbles for the batter to rise. The reaction of baking soda is usually so fast and short-lived that you have to get it into the oven as soon as possible. Letting batter sit in the mixing bowl or scooped out onto a baking sheet for a long time will usually yield poor results.
8. Baking powder is baking soda combined with an acid, usually cream of tartar. (Note: You won’t believe me when I tell you where cream of tartar comes from. So, I am making you look it up. My question to you is: How did anyone ever figure out how to add this to baking soda to making something that causes batters to rise?) Baking powder reacts very quickly, so as with baking soda, it is critical to get the product into the oven expeditiously. Double-acting baking powder has two different types of acids in it. The first reacts at room temperature, forming bubbles that make the batter rise at room temperature as soon as liquid is added to it. The second acid doesn’t react to produce gas bubbles until it reaches a certain hotter temperature.
9. Generally speaking, heating something speeds up the molecules. They don’t just stop moving when the food is removed from the heat source. This is called “carryover heat.” Food keeps cooking after you take it out of the pan or oven. Generally, the bigger the food and/or the denser the food, the more energy it contains, or in other words, the more carryover heat it contains. Thus, you want to take things like roasts out of the oven and eggs out of the pan before they are fully cooked.
10. The denser the cooking medium, the more energy it has and the faster it cooks. Oil is very dense, air isn’t. That is why a deep-fried turkey cooks so much faster in a 350° fryer than a turkey placed in a 350° oven.
For the moment, last month’s column and this month’s column are all the science that I think a basic culinary student needs to know. However, I know that in the next few weeks I will think of other items that should be added to the list. Consequently, don’t be surprised if you happen to see addendums to these two articles in upcoming “50-Minute Classroom”s.
Chef Adam Weiner, CFSE, teaches a 20-week Introduction to Cooking program for JobTrain on the San Francisco Peninsula.