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

by Jeff Potter

  Sure, it might be reasonable to fear corporate overlording—the idea that our food chain might become reliant upon a corporation with a patent on the very food we need to survive—but this is a separate issue from GMO food itself. Another argument against GMO foods claims that the money spent on GMO research would be better spent on other areas of agricultural technology; but again, this is a separate issue from whether genetically modifying food itself should be done.

  I personally do not enjoy burgers served by fast food chains, but I recognize that they are able to feed literally millions of American families every day. Around the world, advances in technology have increased crop yields and improved the quality of life for many, although there are still many in starving conditions. What happens to those families who are just barely making ends meet when the prices of food exceed what they can afford?

  Non-GMO foods are not inherently more expensive, but the economics to date have tended to make the price of GMO foods cheaper. The quick-serve industry is not saying "we want GMO foods"; they’re simply buying what’s most economical, because in a price-sensitive market, the chains need to keep prices down to remain in business.

  For a glimpse into the interconnectedness of our food system, search online for Louise Fresco’s touching TED talk, "On Feeding the Whole World" (http://www.ted.com/talks/louise_fresco_on_feeding_the_whole_world.html).

  Analytical Method

  There have been a number of attempts over the years to devise a scientific model for predicting which flavors will work well together. While not particularly well suited for day-to-day cooking, these types of approaches do have a place in helping create new combinations of flavors and they are used by the food industry and some high-end chefs.

  Note

  A disclaimer: picking pleasing flavors—or at least ones that invoke an emotional response or trigger a memory—is somewhere between an art and a science, so no scientific equation can capture the entire picture. Still, understanding how such a "flavor compatibility algorithm" would work can provide you with a way of organizing your thoughts on food, and for geeks, it’s fun to see how far one can take these sorts of things. If you really want to geek out and need a food project to work on, an open source version of this concept would be fun.

  To start, we need a model of how to describe individual flavors, before considering how to combine them. Odors can be categorized in a few ways, most commonly either chemically or descriptively.

  Chemical taxonomies classify compounds by their odors. Such a taxonomy is essentially a database of chemicals that each map to distinct flavor sensations. For example, Flavornet (http://www.flavornet.org), created by two researchers at Cornell (Acree and Arn), describes some 700+ chemical odorants detectable by the human nose. Listing compounds such as citronellyl valerate (smells like honey or rose; used in drinks, candies, and ice cream), the database is useful for generating certain flavors artificially, but not so useful outside of laboratory kitchens.

  Descriptive taxonomies apply labels to odors as a way of classifying and grouping foods. For example, both lemon and orange are generally classified as "fruity/citrus." Lacking the precision of a chemical taxonomy (the compound is either present or it isn’t), descriptive taxonomies suffer from the subjectivity of human judgment. Most of us would agree that a lemon smells "fruity/citrus," but how much does a food like chocolate smell of the odors in celery? Not much, but certainly more than chocolate smells of fish.

  Note

  The simplest descriptive taxonomy, from the 1950s by J. E. Amoore, proposes just seven primary odors: camphoric (like mothballs), ethereal (like cleaning fluid), floral (like roses), musky (like aftershave), pepperminty, pungent (like acetic acid in vinegar), and putrid (like rotten eggs).

  One modern descriptive taxonomy can be found in the American Society for Testing and Materials’ Atlas of Odor Character Profiles – DS61, by Andrew Dravnieks. While you might not necessarily think of all of the terms included as pleasant, it’s certainly a diverse set, which is useful in thinking about smells. With 146 terms, Dravnieks’s list also provides enough granularity to begin to form a meaningful model for food flavors.

  Common

  Sweet, fragrant, perfumy, floral, cologne, aromatic, musky, incense, bitter, stale, sweaty, light, heavy, cool/cooling, warm

  Foul

  Fermented/rotten fruit, sickening, rancid, putrid/foul/decayed, dead animal, mouse-like

  General foods

  Buttery (fresh), caramel, chocolate, molasses, honey, peanut butter, soupy, beer, cheesy, eggs (fresh), raisins, popcorn, fried chicken, bakery/fresh bread, coffee

  Meats

  Meat seasoning, animal, fish, kippery/smoked fish, blood/raw meat, meat/cooked good, oily/fatty

  Fruits

  Cherry/berry, strawberry, peach, pear, pineapple, grapefruit, grape juice, apple, cantaloupe, orange, lemon, banana, coconut, fruity/citrus, fruity/other

  Vegetable

  Fresh vegetables, garlic/onion, mushroom, raw cucumber, raw potato, bean, green pepper, sauerkraut, celery, cooked vegetables

  Spices

  Almond, cinnamon, vanilla, anise/licorice, clove, maple syrup, dill, caraway, minty/ peppermint, nut/walnut, eucalyptus, malt, yeast, black pepper, tea leaves, spicy

  Body

  Dirty linen, sour milk, sewer, fecal/manure, urine, cat urine, seminal/like sperm

  Materials

  Dry/powdery, chalky, cork, cardboard, wet paper, wet wool/wet dog, rubbery/ new, tar, leather, rope, metallic, burnt/smoky, burnt paper, burnt candle, burnt rubber, burnt milk, creosote, sooty, fresh tobacco smoke, stale tobacco smoke

  Chemicals

  Sharp/pungent/acid, sour/acid/vinegar, ammonia, camphor, gasoline/solvent, alcohol, kerosene, household gas, chemical, turpentine/pine oil, varnish, paint, sulphidic, soapy, medicinal, disinfectant/carbolic, ether/anaesthetic, cleaning fluid/carbona, mothballs, nail polish remover

  Outdoors

  Hay, grainy, herbal/cut grass, crushed weed, crushed grass, woody/resinous, bark/ birch, musty/earthy, moldy, cedarwood, oakwood/cognac, rose, geranium leaves, violets, lavender, laurel leaves

  REPRINTED, WITH PERMISSION, FROM DS61 ATLAS OF ODOR CHARACTER PROFILES, COPYRIGHT ASTM INTERNATIONAL, 100 BARR HARBOR DRIVE, WEST CONSHOHOCKEN, PA, 19428

  Dravnieks’s 146 odor terms, broken down into main categories, provide a good basis for thinking about odors. If you’re heading out on a date and want to impress, this list is a pretty good starting point for describing wines!

  Note

  Another adjective classification system, Allured’s Perfumer’s Compendium, is used by the perfume industry, the fine folks responsible for the smells of products from laundry detergent to toothpaste. Think that new car smell is accidental? Trained employees smell the materials that go into the interior of a new car to make sure that it smells just right. (To quote The Matrix: "You think that’s air you’re breathing now?") Allured’s taxonomy uses more descriptive and narrow scents—familiar items such as banana, peach, and pear—but also specific items like hyacinth, patchouli, and muguet (lily of the valley), making it less useful to the layperson.

  Let’s start by defining a flavor profile as the weighted scores of a collection of terms in a classification system, such as Dravnieks’s 146 odor terms. For every term, imagine taking an item of food—say, a pear—and scoring it on a scale from 1 to 5, where a score of 1 indicates "doesn’t smell like it at all" and 5 is "the very definition of the word!" Given a pear, how much does it smell like a "heavy" odor? 1. Fruity? Maybe a 3? Fragrant? Say it’s a ripe pear, so 4.

  The scoring is not asking if it is a compatible smell, just if the odor label describes the smell. Are the odors you sense in a pear (are the chemoreceptors that fire off in your nose) the same as when you smell other things that are considered fragrant? Given the weights of all of these odor descriptions for a pear, you can plot a graph (almost like a histogram) that you can then compare to similar graphs for other foods.

  Some o
f Dravnieks’s odor terms associated with banana and pear, as scored by a few thousand Internet voters (taller bars indicate a larger degree of agreement between food and odor). These voters were not trained or verified to be familiar with the definitions of those odors; for these reasons, this graph should be treated as a conceptual demonstration only.

  Given such a graph for each individual ingredient in a recipe, you can imagine a combined graph that describes the overall profile of a dish, showing all the "frequencies" present in the smells of each ingredient. Think of it like the various instruments that contribute to a piece of music: each has its own set of frequencies, and the combination of all the instruments makes up the overall song’s frequency distribution. When in tune, the frequencies line up and balance one another; when out of tune, the combination of sounds can be jarringly dissonant, even if each sounds fine individually. Of course, this music analogy isn’t a perfect fit for thinking about flavors: chemical changes brought about by cooking or by reactions between foods change the histogram, and the music analogy doesn’t cover other variables in foods, such as texture, weight, or mouth-feel.

  Many chefs—often pros, but also non-pros who’ve been cooking for years—can imagine flavor combinations in their heads, doing something similar to this process mentally. Just as a composer imagines each voice and track in a piece of music, an experienced cook imagines the profile of the entire dish. Good cooks think about which notes are missing or are too soft and figure out what ingredients can be added to bring up those values.

  What about achieving entirely new pairings, combinations that have no precedence in tradition? This same concept of matching up foods by their flavors can be done via the chemical taxonomy method, given enough time. The high end of the luxury restaurant industry spends an inordinate amount of time working on new flavor combinations, often with upward of two years spent working on a concept before it’s presented. Chef Heston Blumenthal of The Fat Duck (UK) maintains three distinct kitchens, one of which is devoted to laboratory work and is staffed by individuals holding both masters-level degrees in hard sciences like physics or chemistry and degrees from first-tier culinary institutions such as Le Cordon Bleu. Here is a partial list of pairings Chef Blumenthal has used: strawberry and coriander, snails and beetroot, chocolate and pink peppercorn, carrot and violet, pineapple and certain types of blue cheese, banana and parsley, harissa and dried apricot. Give them a try!

  In addition to conducting their own private research, high-end chefs interested in creating new flavor combinations sometimes work with researchers at universities. Both Flavornet (http://www.flavornet.org) and FoodPairing (http://www.foodpairing.be) include such research in their sites. If you’re interested in exploring some of the chemical commonalities between ingredients, look at FoodPairing, which uses a chemical flavor database in order to suggest what ingredients to try together. (FoodPairing claims to be used by Chefs Heston Blumenthal and Ferran Adrià.)

  Food Pairing diagrams for chocolate and chicken. Their database is based on chemical analysis, and it gives suggestions based on both chemical similarity and chemicals known to be complementary.

  GRAPHS USED BY PERMISSION OF BERNARD LAHOUSSE

  The analytical approach tends to be very abstract. There’s little here that helps one select what ingredients to toss into a bowl together to make dinner. For this reason, these sorts of tools have yet to become particularly successful. This technique doesn’t generate recipes. While a set of odors might go together from an aromatic perspective, there are other variables in cooking that prevent mixing and matching various ingredients indiscriminately. For example, one ingredient might require cooking, while another might break down in high heat.

  You can work around these constraints by separating the two ingredients into different components that are prepared separately and combined on the plate—say, a meat with a sauce. Or try using cooking methods that are, in essence, about conveying the perfume in food. Soups, ice creams, even soufflés: all are methods of transporting the flavors and aromas of ingredients without carrying the texture or volume of the original ingredient. A number of more recent, novel flavor pairings have used this solution. At the very least, you might find these types of tools a fun source of inspiration to try new things. Go experiment!

  Harold McGee on Solving Food Mysteries

  PHOTO OF HAROLD MCGEE USED BY PERMISSION OF KARL PETZKE

  Harold McGee writes about the science of food and cooking. He is the author of On Food and Cooking (Scribner), described by Alton Brown as "the Rosetta stone of the culinary world." He also writes a column, The Curious Cook, for the New York Times. His website is at http://www.curiouscook.com.

  How do you go about answering a food mystery?

  It depends on the nature of the mystery. It can start with and mainly involve experiments in the kitchen, doing a particular process several different ways, changing one thing at a time, and seeing what the effect is. Or it can mean going to the food science or technical literature and hunting for information that might be relevant.

  A recent example of the latter would be this column I wrote for the New York Times about keeping berries and fruits longer than normal. I had been going to the farmers’ market and getting way too much fruit. It looked and tasted so good, but I couldn’t eat it all, and after a day, it would begin to mold, sometimes even in the refrigerator. I thought there might be a way to deal with this. So I drove up to UC Davis and used their online databases to search the literature for methods of controlling mold growth on produce.

  I discovered that back in the 1970s some guys at one of the ARS [USDA Agricultural Research Service] stations here in California came up with a mild heat treatment that didn’t damage the fruit but did slow down substantially the growth of mold on the outside. I came back and gave it a try, and it worked. I didn’t have the knowledge or the tools to deal with it without doing some library research. I put it to the test because it’s one thing to read about something in the literature and another thing to make sure that it actually plays out that way in somebody’s kitchen.

  Why not do this kind of literature search online? Is there something that UC Davis or an institution like that is able to provide researchers that they can’t get directly online back home in front of their computers?

  There are wonderful resources that are available at both university and public libraries that an individual just can’t afford to subscribe to. In institutions with a food science department, there are resources on the shelf that you would never know about without going and looking, and I enjoy doing that, not necessarily to answer the question "What do people know today about X?" but more "How have people dealt with X over the centuries?"

  Centuries? Can you give me an example of something from that kind of historical research?

  Tomato leaves are not toxic the way people thought they were. In fact, they’re probably beneficial to eat because they bind to cholesterol and prevent us from absorbing it. The question arose: "How did we get this idea that they’re toxic if they’re not?"

  I delved back as far as I could in some pretty obscure literature to try to figure that out, and that included going up to UC Davis and taking a look at a couple of books from the 17th and 18th centuries on Dutch ethnography of the Pacific. I tracked down a reference to people eating tomato leaves on an island in the Indonesian Archipelago in the 17th century. This would have been shortly after tomatoes had been introduced there because they are not native to that part of the world. That fleshes out the story of how this plant found its way around the world, how it developed a reputation, and the kinds of aesthetic judgments that people made about it.

  In Europe, people didn’t eat the leaves because they thought they stank. In Central and South America, where tomatoes came from, the leaves weren’t much eaten, which I still don’t understand. Just pulling all of these bits together to me is part of the pleasure of understanding and appreciating the food that I sit down and eat at my table today. There is this tremendous d
epth of history and complexity that, if you delve into it, can make it even more pleasurable to eat these things.

  One of the things I like best about the job I have is not so much the writing; it’s the exploring, it’s tracking down these books and reading this paragraph about people on this island centuries ago doing this with the leaves, then coming home and trying to get some sense of what that tasted like using leaves from my own backyard and the equivalent of the preserved fish that they were probably using back then to season them.

  I imagine that our understanding about food is getting more refined, and we’re correcting a lot of previous misconceptions. What do you hope future research will spend time working on?

  If I could name one area that I wish people with the equipment, expertise, and resources would pay more attention to and work harder on, it is flavor and the influence of different cooking methods on the ultimate experience of particular preparations. There are so many interesting questions about different ways of doing the same thing where, at the moment, basically you have your own personal experience and the experience of other people but no good, objective yardstick.

  What are the real differences? Are we experiencing the same set of compounds differently because we have different sensory systems, or do, in fact, different techniques produce different sets of compounds where you happen to prefer this and I happen to prefer that? An example would be making stocks. There are some people who are real partisans of doing stocks in pressure cookers and others who think that the long, slow, barely-at-a-simmer method gives you a superior result. I’ve done both, and I like both, but they are different. I’m not sure I can really explain how they are different, so I would love to know what’s going on there.