Cooking

The preparation of food by the application of heat, changing the food’s structure, texture, flavor, aroma and, or appearance.

Cooking is the application of heat to food. Heat changes a food’s physical properties and makes it more palatable. Some foods aren’t edible, or safe to eat unless cooked sufficiently. Fruit is about the only food that isn’t improved by cooking. There’s really nothing you can do to a perfectly ripe peach to make it better.

Humans lack the ability to easily digest raw starchy carbohydrates. These starchy carbohydrates lack nutritional value to humans unless cooked. Cooking makes food easier to chew and minimizes pathogens. Cooking can concentrate nutrients and liberate nutrients unavailable in the raw state. Cooking can also destroy some nutrients.

In Foundations 1, we explore the application of heat to food. We will see what happens to proteins, fats and carbohydrates when we apply heat. We will also explore the methods of heat transfer in the various dry, and moist cooking methods. Along the way, we will focus on important kitchen skills, including mise en place, safety, sanitation, knife skills and common product knowledge.

Objectives of Cooking

The primary objective of cooking food is to improve its taste and quality. For example, in their raw state, many would find onions or garlic unpalatable. Cooked onions or garlic however, are used in abundance in cuisines around the world. Many vegetables have defenses from being eaten. For onions and garlic, it is their caustic sulfur compounds that keep predators at bay and what we seek to tame in the cooking process.

Cooking foods can reduce the numbers pathogenic organisms in food to levels that are normally considered safe. It is important to understand that cooking however, does not eliminate pathogenic organisms from food. Naturally occurring plant toxins cannot be cooked out but some can be reduced to safe levels. Bamboo shoots, cassava roots, morels are some examples of foods with plant-based toxins that are reduced to safe-levels when properly cooked.

Some foods are difficult, if not impossible for humans to digest and must be processed to remove indigestible parts like husks and shells and then softened in the cooking process. Lacking the complex digestive organs that allow herbivores to eat most any vegetable matter, humans have developed cultivation, processing and cooking techniques that allow us to eat foods like potatoes, rice, grains and legumes. These techniques have also allowed to to increase the variety of foods available to us. Consider all that foods that can be made from soy beans, wheat or corn.

Cooking food softens the food, essentially begins the process of digestion. This allows more food to be eaten and more nutrition to be gained from the food. Consider how long it would take you to chew and eat one pound of raw spinach versus one pound of cooked spinach.

Cooking plants breaks their cell walls, liberating minerals and activating many vitamins like vitamin A and C. A baked potato contains far more vitamin C than a raw potato. Sauerkraut, cabbage cooked by fermentation, contains up to ten times as much vitamin C as raw cabbage. Some water soluble vitamins are lost into the cooking water but even accounting for that loss, cooked vegetables yield a much greater nutritional value. Steaming vegetables (versus boiling) can significantly reduce vitamin loss in vegetables by as much as 97%.

Heat Transfer

When food is cooked, heat is transferred via conduction, convection, or radiation. Most forms of cooking actually involve all three types of heat transfer with one type being the dominant heat source. Conduction involves the direct transfer of heat through direct contact, such as the heat from a frying pan to an egg. Convection involves the transfer of heat via a fluid such as air, water or fat. Deep Frying or steaming would be predominantly convection heat. Radiant heat involves the transfer of energy from waves of heat or light such as microwave cooking or broiling.

Heat Capacity

Imagine a 200°F oven. We know that we can briefly put our hand in that 200˚F oven without getting burned. We also know (or should) that directly touching any metal or food in the oven will likely burn us. Everything in the oven is the same temperature but the rate that the heat is transferred to our skin determines if we will get burned. Liquid water has a very high heat capacity. Touching water at 200˚F would quickly damage your skin. Exposing your skin to 200˚F air would take much longer to feel discomfort or get burned. Oil’s heat capacity is approximately halfway between air and water. Oil’s lower heat capacity or specific heat is also why a given amount of oil will heat up much faster than the same amount of water. In cooking, we utilize the different heat capacities of substances to achieve different effects. Poaching a piece of fish in 165˚F olive oil vs. 165˚F water will result in a more tender and juicer piece of fish

The Effects of Heat on Food

As heat is applied to a protein, the large protein strands uncoil exposing the protein bonds that held the large protein molecules together. As more heat is applied, these exposed bonds reform into curds as the proteins begin to coagulate. In eggs, the whites which are mostly protein are clear and liquid at room temperature. As heat is applied, the proteins reform into tight bonds that prevent light from passing through and the egg starts to turn opaque white. As the protein coagulate, they also trap water, causing meats to firm and liquid eggs to solidify. As the heat continues, or increases, the trapped water is forced out and meats will dry out and eggs become rubbery. Acids have a similar effect on proteins.

Solid fats melt or render, as heat is applied. An oil is a fat that is liquid at room temperature. The temperature or range of temperatures at which different fats melt is an important consideration in cooking. For example, butter has a very narrow range of melting temperatures compared with shortening. A cookie made with all butter will be thin and spread out more than one made with shortening. An oil’s smoke point, the temperature at which an oil begins to seriously degrade and smoke is also a major consideration in cooking with fats.

Carbohydrates, in the form of sugars caramelize as heat is applied. Starches, in the presence of water and heat gelatinize forming a base for thickening sauces or custards.

Browning

There are two types of browning. Enzymatic and non-enzymatic. Enzymatic browning happens when certain enzymes are exposed to oxygen, like the browning that occurs when an apple is sliced. An acid, heat and certain chemicals are used to stop or slow down the enzymatic action. In some cases, enzymatic browning is encouraged for flavor development as in the production of tea or dried fruit like raisins. In other cases, enzymatic browning is detrimental to the appearance or is an indicator of spoilage of certain foods like bananas or shrimp.

Non-enzymatic browning that occurs on foods, usually in the presence of heat, results in the critical formation of flavor compounds. The two main forms of non-enzymatic browning are caramelization and the Maillard reaction.

Caramelization is the browning of sugars, resulting in a nutty flavor and brown color. As the process occurs, volatile chemicals are released, producing the characteristic caramel flavor. The browning of sautéed vegetables and the golden brown color of bread crust are forms of caramelization.

The Maillard reaction is one of the most important processes for flavor development in cooking. It results from a chemical reaction between a protein and certain sugars in the presence of heat. It is commonly seen in caramelized exteriors of roasted meats, the browned exteriors of baked goods and the flavor development of roasted coffee. The process produces hundreds of different flavor compounds. These compounds, in turn, break down to form yet more new flavor compounds, and so on.

Cooking Methods

Cooking methods are classified based on the amount of water used in the process. Dry methods use air or fat as the principle cooking medium, moist methods use steam or water and some methods use aspects of both dry and moist methods.

The Dry Methods (No Added Oil)
- Broiling
- Grilling
- Griddling
- Pan-Grilling
- Roasting
- Baking
The Dry Methods (Added Oil)
- Sautéing
- Pan or Shallow Frying
- Deep Frying
The Moist Methods
- Poaching
- Blanching
- Simmering
- Boiling
- Steaming
- Braising
- Stewing
- Poêléing