Cooking for Geeks: Real Science, Great Hacks, and Good Food

by Jeff Potter

  Well, French people, and this is a generalization, because it’s not necessarily true for everybody, but they’re much more relaxed about how things look. Americans jumped on the fast food wagon in the 50s and 60s, whereas the French jumped on it in the 90s and now; so they’re losing that whole connection with homemade things, but they still are closer to it than we are. It’s not unusual to go to someone’s house for lunch and they made a quiche; whereas, in America, you’d be like, "Oh my God, I can’t believe you made that, you made the crust, you made the filling, you chopped the vegetables?" That’s changing here [in France]; everyone is eating frozen food now.

  Is there any sort of cultural backlash against that from part of the French community?

  Not yet. Americans have seen our cuisine decline and are now interested in farmers’ markets and all that stuff, whereas the French didn’t fall as far as we did. They’re like, "Everything at the market is local, and is fresh." I’m like, "Well, everything’s from Morocco, look at the box." To which they say, "Oh, well, it’s not like America."

  But you’re saying Europe is actually becoming more like America, in that sense?

  Yeah.

  What do you think of people who really feel like they need to have the most up-to-date technical equipment and toys?

  Well, that’s an American thing. I go back to America and everyone has wine refrigerators, and they’re filled with Kendall Jackson Chardonnay. If you have good wine, you don’t put it in one of those refrigerators, because they have compressors that shake, which is bad for wine. Unless you have a very good wine refrigerator that doesn’t shake, you’re better off without it. It’s funny to see people who have wok burners and wine refrigerators and all that stuff in their house. A lot of people want to have the illusion of cooking; they want to have all these bottles of olive oil wrapped up on the counter in baskets and things, but on the other hand, do they really need all that stuff?

  It sounds like one piece of advice you would give to somebody is to not obsess over equipment?

  Yes. You don’t need every saucepan in the world, you need like three. For me, having a mixer is very important; for me, having an ice cream machine is important. But you don’t need a panini grill; you can use your skillet and just put a weight on top of it, something like a can of tomatoes, and there you have it.

  PHOTO OF DAVID BY KRISTIN HOHENADEL/APARTMENT THERAPY: THE KITCHN

  * * *

  [3] Technically, a suboptimal pie-cutting protocol

  Chapter 6. Playing with Chemicals

  MANKIND HAS BEEN ADDING CHEMICALS TO FOOD FOR MILLENNIA. Salt is used both as a preservative (curing meats, inhibiting bacterial growth) and as a flavor enhancer (masking bitterness). Acetic acid, a key component in vinegar and a byproduct of some strains of bacteria, turns cucumbers into pickles and cabbage into the Korean dish kimchi. And citric acid in lemon juice brightens the smell and taste of fish by neutralizing the amine compounds that can create that "fishy" smell as the tissue breaks down.

  In recent history, the food industry—the collection of businesses that farm, distribute, prepare, and package the foods we eat—has developed a number of techniques to help perishable foods last longer. Refrigeration slows down bacterial growth, "modified atmosphere packaging" (MAP) displaces oxygen to reduce oxidation and retard the growth of aerobic bacteria, and chemical food additives extend shelf life, fortify foods, and aid in mass production. These same chemicals are also used to create entirely new types of foods, including many candies, and as key ingredients in some techniques of an entirely new kind of cooking given names such as molecular gastronomy or modernist cuisine.

  By definition, food itself is made up of chemicals, of course. Corn, chicken, and bars of chocolate are just big piles of well-structured chemicals. For our purposes, we’ll consider a food additive to be any chemical—a compound with a definable molecular structure—used in food that by itself cannot be harvested directly from nature without further refinement or processing.

  In this chapter, we’ll take a look at cooking techniques that use food additives, both traditional and modern. Some recent culinary techniques rely on chemical stabilizers, gelling agents, and emulsifiers to create new types of dishes. We’ll cover these chemical-based techniques in the second portion of this chapter. Even if you’re not the type who wants to use chemicals to make foams, to "spherize" liquids, or to turn liquids into gels, understanding how food additives work and what they do makes recovering from kitchen errors quicker and decoding ingredient lists easier.

  One of the largest challenges facing commercial food preparers is extending shelf life while maintaining the taste, texture, and appearance of foods. To reduce costs, speed up manufacturing, and increase the shelf life of products like vegetables and baked cookies from days to months, industry relies on chemicals.

  Take a look at the food additives used in a certain popular cream-filled chocolate cookie:

  Baking soda (a.k.a. sodium bicarbonate)

  Speeds up manufacturing by immediately giving rise to a dough or batter (via chemically reacting to release carbon dioxide) so you don’t have to wait for the rising action of yeast.

  Cornstarch

  A thickener, also used as a stabilizer. (Cornstarch is derived from corn but is sufficiently processed, filtered, centrifuged, dried, and treated with acids that it should be considered a food additive.)

  Enriched flour (wheat flour, niacin [B3], reduced iron, thiamin mononitrate [B1], riboflavin [B2], folic acid [B9])

  Fortified with micronutrients that are removed during the processing of white flour. The FDA requires that white flour be supplemented with B vitamins (to prevent various deficiencies) and iron (to prevent anemia, a low red blood cell count).

  Salt (a.k.a. sodium chloride)

  Used to mask bitterness, to improve flavor, and in some cases to act as a preservative.

  Soy lecithin

  An emulsifier, used to prevent oils and water from separating. If you were following a recipe for a cream filling, it would likely call for egg yolks, which are around 10% lecithin, as an emulsifier.

  Vanillin (artificial flavor)

  Used as a flavoring agent, vanillin is the primary component of natural vanilla extract and is responsible for the majority of vanilla’s flavor. Vanillin has the molecular formula C8H8O3, regardless of whether the source from which it is derived is "natural" or "artificial."

  Some of these items—baking soda, cornstarch, and salt—might not strike you as food additives, either because of their "natural" origins or their long history in the kitchen. But even baking soda arrived only relatively recently on the food scene, when in 1846 John Dwight and Austin Church figured out a commercial method for manufacturing it.

  Food additives are used for the following purposes:

  To preserve nutritional value (preventing the breakdown of food)

  To address dietary needs (via fortification, such as the addition of iodide in table salt)

  To extend shelf life or stability in order to keep the food enjoyable longer (e.g., treating apricots with sulfur dioxide to preserve color)

  To aid in manufacturing, processing, or transportation—that is, to address issues caused by scaling to mass production (i.e., keeping larger volumes of food consistent)

  Most commercially prepared food products use food additives for more than one of these purposes. In the cookie example just cited, baking soda speeds up manufacturing, cornstarch and soy lecithin aid in the manufacturing process, salt and vanillin improve flavor for enjoyment, and flour is fortified to address dietary needs.

  Food additives have gotten something of a bad rap in recent years. The politics, economics, and trade-offs of a food supply that is necessarily driven by economics are well beyond the scope of this book. For now, keep in mind that food itself is chemical, and to cook is to cause chemical and physical reactions.

  Just as there have been food additives that were once thought safe but turned out to be dangerous (e.g., red dye no.
2), there are "natural" items—foods from the earth—that pose their own risks without human processing (e.g., hydrocyanic acid in raw lima beans, which is neutralized by cooking). The source of a chemical—natural versus man-made—should not be your sole distinguisher of safety. No one would argue that hemlock or botulinum toxins—both "all natural"—are things you should be adding to your midnight snack.

  Note

  Taste tests done by America’s Test Kitchen have found that most pastry chefs are unable to discern the difference between natural and artificial vanilla, much to the chefs’ embarrassment.

  Traditional Cooking Chemicals

  Before getting into modern industrial chemicals—chemicals that began to routinely appear in food only after World War II—let’s take a look at some traditional food additives and the chemicals and chemistry behind them: salt (sodium chloride), sugar (sucrose), acids and bases (citric acid, lye), and alcohol (ethanol).

  Salt

  Ahh, salt: responsible for the salvation of many a food (or is that salivation?). The oldest seasoning in use, in small quantities it helps reduce the bitterness of foods and enhances the other flavors in a dish (for a discussion of the gustatory system, see Taste (Gustatory Sense) in Chapter 3). In larger quantities, it can be used chemically to preserve food (dry and wet brining) as well as mechanically to alter how foods cook (salt roasting).

  Salt crystals.

  IMAGE COURTESY OF NASA

  From a chemistry perspective, salt is an ionic compound composed of a cation from a metal or ammonium and an anion from an acid. In solid form, salt is a crystal of atoms arranged in an alternating pattern based on charge: cation, anion, cation, anion, arranged in a 3D checkerboard pattern.

  Our tongues detect one kind of salt, sodium chloride, as being "salty." Sodium chloride (common table salt) is made up of sodium (a metal, and one that in its pure form happens to react violently when dropped in water) and chloride (chlorine with an extra electron, making it an anion). Other salts can register as different tastes. Monosodium glutamate, for example, triggers our taste receptors for umami. In water, the salts dissolve and the individual ions are freed, and they are then able to react and form bonds with other atoms and molecules.

  While at first glance the chemistry of salt may not seem important to everyday cooking, it’s helpful to understand the basics of how it works when preparing and cooking food. Here’s a quick refresher on a few chemistry definitions that’ll pop up throughout this chapter. (Finally, a use for that high school chemistry!)

  Atom

  Basic building block of matter; these are the elements listed in the periodic table.

  Molecule

  Two or more atoms bonded together (where "or more" can be millions). H = hydrogen atom, H2 = dihydrogen molecule.

  Cation

  Any positively charged atom or molecule (i.e., one that has more protons than electrons).

  Anion

  Any negatively charged atom or molecule (i.e., one that has more electrons than protons).

  Note

  Cations and anions can be a single atom (Ca2+) or anything from a small molecule (NO3) to a really large one, such as alginate (composed of many thousands of atoms).

  Osmosis and Salt

  Applying salt to the outside of fish causes osmosis, which is the physical process of a solvent passing through a membrane to equalize the concentration of solute on the membrane’s other side.

  In animal tissue, salt (the solute) is unable to penetrate the cell walls (the membrane) present in the tissue, so water (the solvent) leaves the cells in order to equalize the differences in concentration. (The process of equalizing osmotic pressure is called diffusion.) If there’s a large enough difference in solute concentrations, at some point plasmolysis occurs—the cell structure collapses—and if enough water leaves the cell, the cell dies.

  From a food safety perspective, the amount of salt necessary to cause sufficient plasmolysis to render bacteria nonviable depends on the species of bacteria involved. Salmonella is unable to grow in salt concentrations as low as 3% and Clostridium botulinum dies at around 5.5%, while Staphylococcus is hardy enough to survive in a salt concentration up to 20%. Staphylococcus is not a common concern in fish, according to the FDA, so food safety guidelines consider salt solutions of ~6% sufficiently safe (except for those in an at-risk group) when curing fish.

  Dry brining

  Beef jerky, salmon gravlax, sausages, hams, prosciutto, and corned beef are all cured using salts, typically sodium chloride (table salt) or sodium nitrate, which gives foods like salami a distinctive flavor and pinkish color. Besides adding flavor, salt preserves these types of foods by creating an inhospitable environment for microorganisms (see the section Foodborne Illness and Staying Safe in Chapter 4).

  Salt curing has been used for centuries to preserve fish caught at sea, and it’s also something that you can easily do at home. Surrounding it with a sufficient quantity of salt draws moisture out of food; this is called dry brining. But salt doesn’t just "dry out" the food (along with any bacteria and parasites). At sufficient concentration, it actively disrupts a cell’s ability to function and kills it, rendering bacteria and parasites nonviable.

  Note

  This killing ability isn’t limited to just foods. For an adult human, the lethal dose of table salt is about 80 grams—about the amount in the saltshaker on your typical restaurant table.

  Overdosing on salt is reportedly a really painful way to go, as your brain swells up and ruptures. Plus, it’s unlikely the ER physicians will correctly diagnose the cause in time. (Paging Dr. House.)

  Wet brining

  Wet brining—the process of soaking meat in salted water—can be used both to add flavor and to reduce water loss during cooking.

  As an experiment, try doing an A/B test with brined and nonbrined pork chops. Does brining change the weight loss during cooking? Using a gram scale, weigh a pork chop prebrining, post-brining, and after cooking, and compare the percentage weight loss to that of a "control" pork chop that is cooked without having been brined. You may also want to test how brining changes the flavor. If you’re cooking for others, enlist them as tasters. Cook both brined and nonbrined pork chops, serve a portion of each to everyone, and see what preferences your tasters have.

  Salmon Gravlax

  In a bowl, mix together:

  5 teaspoons (30g) kosher salt

  1 tablespoon (12g) sugar

  3 tablespoons (12g) finely chopped fresh dill

  1 teaspoon (4g) vodka

  1 teaspoon (2g) crushed peppercorns (ideally, use a mortar and pestle)

  On a large piece of plastic wrap, place:

  1 pound (450g) salmon, washed and bones removed; preferably a center cut so that its shape is rectangular

  Sprinkle salt mixture over fish and massage into salmon. Wrap fish in plastic and store in fridge, flipping and massaging twice a day for a day or two.

  Store in the fridge and consume within a week.

  Notes

  Note the use of vodka as a solvent. Try substituting other spirits, such as cognac or whiskey. And in place of dill, try using coriander seed, loose tea leaves (e.g., Earl Grey or Lapsang Souchong), shallots, or lemon zest. The Scandinavians traditionally serve salmon gravlax on top of bread with a mustard dill sauce.

  You can substitute other fatty fish for the salmon and obtain a similar texture. What happens if you try tuna?

  Curing inhibits most common bacterial growth but does not prevent all types of bacteria from growing. Avoid serving this to anyone in an at-risk group. This recipe is a bit heavy on the salt—6% by weight—to err on the side of safety. You can reduce the saltiness by rinsing the finished product in fresh water, followed by recoating it with dill and ground pepper to restore some of the flavor. For food safety issues related to parasites, see the section How to Prevent Foodborne Illness Caused by Parasites in Chapter 4.

  Note

  For an extremely technical guide to curing fish and
potential pathological hazards, see http://www.fda.gov/Food/ScienceResearch/ResearchAreas/SafePracticesforFoodProcesses/ucm094579.htm; for a more practical guide, see http://www.cfast.vt.edu/downloads/fstnotes/salting.pdf.

  Salt curing—as is done in salmon gravlax—is the first step in making lox. After curing, lox is also cold smoked, which is the process of exposing a food to smoke vapors that have been cooled down. You can approximate the flavor of lox by adding liquid smoke to the rub (see Liquid Smoke: Distilled Smoke Vapor).

  You can remove the skin from a piece of fish by placing it skin-side down on a cutting board and carefully running a knife along the surface between the skin and flesh while using your hand to keep the fish from sliding around.

  Pork Chops Stuffed with Cheddar Cheese and Poblano Peppers

  Brined pork chops are a good example of wet brining. This is also one of those dishes that’s both tasty and easy.

  In a container, mix 2 tablespoons (60g) salt with 4 cups (1 liter) of cold water. Stir to dissolve salt. Place 2 to 4 boneless pork chops in the brine and store them in the fridge for an hour. After pork chops have brined, remove from water and pat dry with paper towels. Lay out the pork chops on a clean plate to allow them to come to room temperature.