Surface chemistry of cooking

In cooking several factors, including materials, techniques, and temperature, can influence the surface chemistry of the chemical reactions and interactions that create food. All of these factors depend on the chemical properties of the surfaces of the materials used. The material properties of cookware, such as hydrophobicity, surface roughness, and conductivity can impact the taste of a dish dramatically. The technique of food preparation alters food in fundamentally different ways, which produce unique textures and flavors. The temperature of food preparation must be considered when choosing the correct ingredients.

The interactions between food and pan are very dependent on the material that the pan is made of. Whether or not the pan is hydrophilic or hydrophobic, the heat conductivity and capacity, surface roughness, and more all determine how the food is cooked.

Stainless steel is considered stainless because it has at least 11% chromium by mass. Chromium is a relatively inert metal and does not rust or react as easily as plain carbon steel. This is what makes it an exceptional material for cooking. It is also fairly inexpensive, but does not have a very high thermal conductivity. From a surface standpoint, this is because of the thin layer of chromium oxide that is formed on the surface. This thin layer protects the metal from rusting or corroding. While it is protective, the oxide layer is not very conductive, which makes cooking food less efficient than it could be. For most cooking applications, high thermal conductivity is desirable to create an evenly heated surface on which to cook. In this way, stainless steel is usually not considered high-grade cookware.

In terms of surface interactions, chromium oxide is polar. The oxygen atoms on the surface have a permanent dipole moment, and are therefore hydrophilic. This means that water will wet it, but oils or other lipids will not.

Cast iron cookware is seasoned with oil. The surface of the cast iron is not very smooth; it has pits and peaks that are not conducive to cooking. Typically, the cookware is seasoned with oil. This process leaves a thin coat of oil in the pits and on top of the peaks on the surface of the pan. This thin coat actually polymerizes, making it durable and lasting. It also prevents the cast iron from rusting, which it is prone to do. The oil that is used in a seasoned pan combines with any liquid that is used in the cooking process and creates a good contact between pan and food. Even though the cast iron itself is a poor heat conductor, the oil makes the pan effective when it is at a high temperature.

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