This article was originally posted on RealClearScience.
Cooking and organic chemistry have a lot in common. Both employ esoteric language and precise, step-by-step instructions. Chefs and chemists alike put strange ingredients into fancy glassware, apply heat, and create something new.
The parallels between the two professions were not lost upon the authors of Modernist Cuisine: The Art and Science of Cooking, a five-volume set that describes, among many other things, how to concoct bizarre meals using equipment typically found in a laboratory. (Pea butter and drinkable bagels, anyone?) Similarly, a new commentary by Michael Brenner and Pia Sorensen in the journal Cell highlights molecular gastronomy, a burgeoning field that seeks to apply the principles of chemistry to food for the purpose of expanding textures and flavors.
One of the more striking examples that the authors discuss is how changing the temperature at which an egg is cooked can have radically different outcomes. When an egg is placed in boiling water (100 deg C.), the high temperature causes the proteins inside to lose their natural shape (a process called “denaturation”) and to form different bonds. It is for these chemical reasons that the texture of the egg changes. However, if the egg is cooked at a lower temperature, say 65 deg C., the transformation at the molecular level will not be nearly as extensive, and an entirely different texture arises. Amazingly, as the authors write, “a well-trained chef can predict the temperature of the water bath within a half a degree based on the texture of the egg, and eggs cooked even just a couple degrees apart have very different culinary applications.”
Another culinary peculiarity is “hot ice cream.” Most people are familiar with gelling agents, such as gelatin, which can be found in products like Jell-O. Unfortunately, it is not possible to eat “hot Jell-O,” as the gelatin would melt. There are gelling agents, however, which form a gel at higher temperatures (50-90 deg C.), and adding them to flavored cream allows for the enjoyment of hot ice cream, which apparently feels and tastes just like its colder counterpart.
The authors then turn their attention to flavor, and they discuss three main ways for chef-chemists to enhance or create new ones:
Concentration. A centrifuge is a device that spins liquids placed in bottles at a high velocity. The centrifugal force causes particles to fall out of solution, forming a sludge at the bottom. This process can concentrate flavor molecules, and it is precisely how pea butter is made. AsPopular Science describes:
Fresh peas are blended to a puree, then spun in a centrifuge at 13 times the force of gravity. The force separates the puree into three discrete layers: on the bottom, a bland puck of starch; on the top, vibrant-colored, seductively sweet pea juice; and separating the two, a thin layer of the pea’s natural fat, pea-green and unctuous.
The centrifuge isn’t the only tool available for concentrating flavors. The rotovap evaporates, condenses, and collects volatile aroma compounds by applying a partial vacuum. One Spanish chef uses the rotovap to collect scents from eucalyptus leaves and forest soil.
Chemical reaction. Any process that involves the swapping of electrons is a chemical reaction, during which the fundamental nature of the reactants is changed. Melting an ice cube is not a chemical reaction because the same molecule, water, is present before and after the transformation. Boiling an egg, however, is an example of a chemical reaction. So is the browning of meat and breads in a mouth-watering process called the Maillard reaction (which, incidentally, may be partially responsible for triggering peanut allergies).
Fermentation. Fermentation is a special type of chemical reaction that involves microbes. Bacteria and yeast can convert various organic molecules into waste products, deriving energy in the process. Remember, though, that one organism’s junk is another’s treasure. From the yeast’s point of view, the alcohol in beer and wine, the world’s most popular fermented beverages, is nothing more than useless garbage. But for brewmasters and vintners, it is liquid gold. Intrepid chefs are now trying their hands at microbiology, mixing unorthodox foods and microbes in the hopes of inventing the next culinary phenom.
The authors argue that, increasingly, chefs have taken science into the kitchen. Thus, it is imperative to gain a more thorough understanding of the chemistry of cooking in order to fully unleash the modernist revolution. Aspiring chefs, therefore, ought to pay close attention in their high school science classes.
Source: Michael P. Brenner and Pia M. Sorensen. “Biophysics of Molecular Gastronomy.” Cell 161 (1): 5–8. Published: 26-March-2015. DOI: http://dx.doi.org/10.1016/j.cell.2015.03.002