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

by Jeff Potter

  What was the original reason you and Dr. Kurti had for picking the name "molecular and physical gastronomy"?

  Nicholas Kurti was a retired professor of physics. He loved cooking, and he wanted to apply new technology in the kitchen, ideas from the physical lab, mostly vacuum and cold, low temperatures. For myself, the idea was different: I wanted to collect and test the old wives’ tales of cooking. Also, I wanted to use some tools in the kitchen that were already in chemistry labs.

  For many years, when I was doing an experiment in Paris, he was repeating it in Oxford, and what he was doing in Oxford, I was repeating in Paris. It was great fun. In 1988, I proposed to Nicholas to create an international association of the kind of thing that we were doing. Nicholas said to me that it was too early but, probably, it would be a good idea to make a workshop with friends meeting together. This is why we needed a name, so I proposed molecular gastronomy, and at that time, Nicholas, who was a physicist, had the feeling that that would put too much emphasis on chemistry, so he proposed molecular and physical gastronomy. I accepted the idea only because Nicholas was a great friend of mine, not because I was convinced scientifically.

  In the beginning, I published a paper in a main journal in organic chemistry, and in this paper I made the confusion between technology and science. In 1999, I realized that a clear distinction should be made between engineering and science because it is different.

  How does the work that you do with molecular gastronomy differ from what a food scientist does who publishes in journals such as the Journal of Food Science?

  It is a question of history. At that time [1988], food science was more the science of food ingredients or food technology. You had papers on, let’s say, the chemical composition of carrots. Nicholas and I were not interested at all in the chemical composition of carrots, in the chemistry of ingredients.

  We wanted to do science, to explore the phenomena that you observe when you cook, and cooking was completely forgotten at that time. In the previous centuries, Lavoisier and others studied how to cook meat broth. This was exactly what we are doing. Food science had drifted; cooking was completely forgotten. Recently, I took the 1988 edition of Food Chemistry by Belitz and Grosch—a very important book in food science—and looked at the chapters on meat and wine. There is almost nothing about cooking wine or cooking meat; it is very strange.

  It seems like there is much confusion about what you mean with the term "molecular gastronomy."

  Molecular gastronomy means looking for the mechanism of phenomena that you observe during cooking processes. Food science in general is not exactly that. If you look at the table of contents of the Journal of Agricultural and Food Chemistry, you will see very little material referring to molecular gastronomy.

  So, molecular gastronomy is a subset of food science that deals specifically with transformation of food?

  Exactly, it is a subset. In 2002, I introduced a new formalism in order to describe the physical organization of colloidal matter and of the dishes. This formalism can apply to food and also to any formulated products: drugs, coatings, paintings, dyes, cosmetics. It has something to do with physical chemistry and, of course, it has something to do with molecular gastronomy. So it’s true that molecular gastronomy is a particular kind of food science, but also it’s a particular kind of a physical chemistry.

  It’s fascinating to see how easy it is to make inventions or applications from science. Every month I give an invention to Pierre Gagnaire. I should not, because it is invention, not discovery, but I can tell you that I just have to snap the finger and the invention is there. I take one idea of science, I ask myself, "What can I do with that?" and then I find a new application. It is very, very easy. The relationship is of use, and this is probably the reason why there is so much confusion between science and technology. We’ve been studying carrot stocks. We were studying what is going out of carrot roots into the water and how is it going out. One day, I came to the lab. I was looking at two carrot stocks made from the same carrot. One stock was brown, the other was orange. It was the same carrot, same water, same temperature, same time of cooking, and one stock was brown; the other was orange. I stopped everybody in the lab saying, "We have to focus on this, because we don’t understand anything."

  We focused on this story, and it was due to the fact that one preparation was made in front of light, and the other was in the darkness, and, indeed, we discovered that if you shine some light on the carrot stock, it will turn brown. So we explored the mechanism, how it turned brown. It was a discovery, not an invention, and thus it was science. At the same time, the application is of use, because cooks want to get a beautiful golden color to stocks, and in order to get the brown color, they grill onions and they put them in the stock. I can tell cooks now: avoid the onions and just add some light. So you see, the discovery is leading to invention immediately.

  Tell me more about your collaboration with Chef Pierre Gagnaire.

  I don’t know if it is a collaboration, it’s a friendship. Pierre’s wife told Pierre more than 10 years ago, "You’re crazy and Hervé is crazy, so you probably could play together."

  The real story is that, in 1998, Pierre opened a new restaurant in Paris. He was launching the restaurant with lunches for the press, for the media, for politics, etc., and I was invited. I did not know him, except from reputation at the time. One year passed, and I was asked by the newspaper Libération for recipes for Christmas—scientific recipes. I told them I’m not a chef, and that I should not give recipes. I proposed, instead, that I would invite two wonderful chefs to do recipes from ideas that I would give to them, and Pierre Gagnaire would be one of the two chefs.

  When I was in the cab driving to the restaurant for the interview and the picture, I realized that beer can make a foam. It means that you have proteins that are surfactants that can wrap the air bubbles. If the proteins can wrap the air bubbles, it means that they can wrap oil. When I arrived in the restaurant, Pierre was there; immediately I asked him, "Do you have some beer, and some oil, one whisk and one bowl?" He looked at me, and he asked for the ingredients and the hardware, and I told him, "Please, put some beer and then whisk the oil into the beer; I can predict that you will get an emulsion." And he got it. He tasted the emulsion, and he found it very interesting, and he decided to make the dish after this wonderful emulsion.

  One year later I was invited to lecture at the Academy of Sciences. I proposed to them to make the lecture with a dinner from Pierre. We worked for three months, meeting every Monday morning between 7 and 10. It was so fun that we decided that we had to play on and we never stopped. It’s not collaboration, it’s just playing together, where we are children.

  It seems like some of the more novel cuisines that places like elBulli or Alinea do are removed from the normal dining experience. How much of that experience is created by taking scientific discoveries and applying them to a meal, as opposed to a chef having a concept and coming to a scientist and asking is there a way to make this?

  Well, there are many questions in that one. I have the feeling that we don’t cook the way we should. For example, we are still roasting chicken. Is it a good idea? I don’t know. We ask the question, "Should we go on as we always have?" Many chefs are changing their ways. Many of my inventions are free on Pierre Gagnaire’s website (http://www.pierre-gagnaire.com/francais/cdthis.htm), and I know that chefs go there to get ideas for the kitchen. I publish the ideas for free; there are no patents, there is no money involved. It is all for free because I want to rationalize the way we cook. We don’t cook in a rational way. We are still roasting chicken.

  For one of the books that I published, the title was translated as Cooking: A Quintessential Art, but in French it was Cooking: Love, Art and Technique. The idea that cooking is an art was not even admitted some years ago: "Real art is painting or music or sculpture or literature." I remember talking with a minister of public education in France. He was saying, "No, no, no, it’s not art. You’re just jok
ing; it’s cooking." It’s love first, then art, then technique. Of course, technology can be useful only for the technical part, not for the art, and not for the love component. Nowadays, Ferran of elBulli and Alinea’s Grant Achatz are using the technique, but there are a lot of possibilities for improvement. They will make their own interpretation, and then science has nothing to do with that. It is personal interpretation; it is feeling.

  Do you think that elBulli and Alinea, or restaurants like them, are able to sufficiently use all three components: love, art, and technique?

  The love component of cooking is not really formalized. The science needed is still not there. I have the idea that we need to do some science on the love component. Because I’m a physical chemist, it’s not very easy for me to make this study. It’s still very primitive. Currently, the chef behaves intuitively with the love component. If someone is friendly, he will greet you at the entrance of the restaurant, "Ah, here you are, very happy to have you," and you are happy because you’re greeted as kind of a friend. But this is intuition. What I’m saying is that we need to scientifically study the mechanism of phenomena of this friendship. We don’t have this mechanism currently.

  It almost sounds like psychology or sociology.

  It is, exactly. My way of doing molecular gastronomy is to do physical chemistry, daily, at the lab, but I’m producing the concepts so that other people can pursue them in their own way. Their own way can be psychology, sociology, history, geography; we need the knowledge to understand the mechanism of phenomena that we observe in cooking. It is a very foolish idea to think that we cannot investigate all the phenomena. It can be done. Imagine that I discover, or someone discovers, a way to give more love to a dish. It means that the guest will be happier. But imagine that you give this knowledge to a dishonest guy, then the guy would use the knowledge dishonestly, and this will increase the power of dishonest people. If you give the same knowledge to kind people, they will do their best. This is the same question as with nuclear physics. If you are acting poorly, you will make a bomb; if you try to act for the good of humankind, you will make electricity. Science is not responsible for the application; you are responsible for the application.

  I asked Dr. This if he had a favorite experiment that could be done at home to learn more about food. His reply:

  The most exciting discovery that I did was to put fruits like plums in various glasses full of water but with different quantities of sugar dissolved. In light syrups the fruits sink, but in concentrated syrups they float. This is, of course, linked with density, but when you wait, the fruits in light syrups swell (by osmosis) and explode, whereas they shrink in concentrated syrups.

  This experiment is useful to know how to make a syrup of the exact concentration for preserving fruits: put them in concentrated syrup and slowly add water until they begin sinking. The osmotic pressure is then nil so that they will keep their shape and consistency.

  Left: cherries in water only; center: cherries in a light sugar syrup; right: cherries in a heavy sugar syrup.

  Acids and Bases

  We’ve already discussed chemical reactions that generate air via acid neutralization with baking powder and baking soda in Chapter 5 (see Chemical Leaveners), but there’s more to pH in cooking than just that. Acids and bases are commonly used to adjust the pH level for two reasons: to cook foods and to prevent foodborne illness.

  When it comes to cooking with acids, ingredients such as lime juice can be used to essentially "cook" the proteins in items like shrimp and fish, resulting in similar changes to those that happen when applying heat. On the molecular level, a protein in its native state is structured so as to balance the various attracting and repulsing charges between both its internal regions and the surrounding environment. Portions of proteins are nonpolar—flip ahead a few pages to the section on "When a Molecule Meets a Molecule" to read about polarity—while water is polar. Because of this, proteins normally contort and fold themselves up so that the polar regions of their structures are arranged in a stable shape. Adding an acid or base denatures a protein by knocking its charges out of balance. The ions from an acid or base are able to slip into the protein’s structure and change the electrical charges, causing the protein to change its shape. For dishes like ceviche (citrus-marinated seafood), the acid from the lime or lemon juice literally causes a change on the molecular level akin to cooking. And this change doesn’t just happen on the surface—given sufficient time, acidic and basic solutions will fully penetrate a food.

  When it comes to food safety, adjusting the pH level of the environment can both destroy any existing bacteria or parasites and also prohibit their growth. Ceviche is a classic example of this. Vibrio cholerae—a common seafood-borne pathogen—rapidly dies in environments with a pH level below 4.5, even at room temperature. With sufficient lime juice, V. cholerae will not survive. Or consider cooked white rice. Left out at room temperature, it becomes a perfect breeding ground for Bacillus cereus: it’s moist, at an ideal temperature, and has plenty of nutrients for bacteria to munch away on. (Uncooked rice is dry, and since bacteria need moisture to reproduce, they remain dormant. See the FAT TOM variables from Foodborne Illness and Staying Safe for more.) But drop the pH level of the rice by adding enough rice vinegar—down to about 4.0—and the rice falls well outside a hospitable range for bacteria to grow. This is why proper preparation of sushi rice is so critical in restaurants: failure to correctly adjust the pH level can result in sickening diners.

  Note

  Spores for B. cereus are highly prevalent in soil and water; they’re essentially impossible to get rid of. They’re heat-stable, too—you can’t boil them away. Whoever joked about cockroaches being the only thing to survive a nuclear blast clearly hadn’t read up on these things.

  Scallop Ceviche

  This scallop ceviche is a simple dish to prepare, and surprisingly refreshing on a warm summer day. It’s also a good example of how acids—in this case, the lime and lemon juices—can be used in cooking.

  In a bowl, mix:

  ½ cup (130g) lime juice

  ¼ cup (60g) lemon juice

  1 small (70g) red onion, sliced as thinly as possible

  2 tablespoons (20g or 1 bulb) shallot, thinly sliced

  2 tablespoons (18g) olive oil

  1 tablespoon (15g) ketchup

  1 clove (7g) garlic, chopped or run through a garlic press

  1 teaspoon (4g) balsamic vinegar

  Add and toss to coat:

  1 lb (500g) bay scallops, rinsed and patted dry

  Store in fridge, toss again after two hours, and store overnight to give sufficient time for acid to penetrate scallops. Add salt and pepper to taste.

  Notes

  Try slicing one of the scallops in half after two hours. You should see a white outer ring and a translucent center. The outer ring is the portion that has had time to react with the citric acid, changing color as the proteins denature (just as they would with heat applied). Likewise, after marinating for a day or two, a sliced scallop should show a cross-section that’s entirely white.

  Keep in mind that the pH of the marinade is important! At least 15% of the dish should be lime or lemon juice, assuming the remaining ingredients are not extremely basic. Lime juice is more acidic than lemon juice (pH of 2.0–2.35 versus 2.0–2.6).

  Try adding minor quantities of herbs like oregano to the marinade or adding cherry tomatoes and cilantro to the final dish (after marinating).

  Note

  What, you’re worried that the scallops are still "raw" and full of bacteria? To quote from the literature: "In the face of an epidemic of cholera, consumption of ceviche prepared with lime juice would be one of the safest ways to avoid infection with [Vibrio] cholerae." (L. Mata, M. Vives, and G. Vicente (1994), "Extinction of Vibrio cholerae in acidic substrata: contaminated fish marinated with lime juice (ceviche)," Revista de Biologiá Tropical 42(3): 472–485.)

  Still, since some types of bacteria can withstand more extrem
e environments, if you really want to play it safe, avoid serving this to anyone in an at-risk group.

  Mozzarella Cheese

  Making your own cheese is neither a time-saver nor a money-saver, but it’s a great experiment to see how closely related two seemingly different things can be. Cheese is made from curds—coagulated casein proteins—in milk. The whey is separated out via an enzymatic reaction, allowing the curds to be cooked and then kneaded, stretched, and folded to create that characteristic structure found in string cheese.

  Note

  American string cheese is really mozzarella cheese that’s been formed into long, skinny logs. Other countries make string cheese using goat or sheep’s milk, sometimes adding in cumin seeds and other spices, and often braid several thin strands together.

  You’ll need to order a few chemicals to do this. (See the upcoming notes and the sidebar Buying Food Additives for how to do so.) In two small bowls or glasses, measure out and set aside:

  ½ teaspoon (1.4g) calcium chloride dissolved in 2 tablespoons distilled water

  ¼ tablet rennet, dissolved in 4 tablespoons distilled water (adjust quantity per your rennet manufacturer’s directions)

  In a stock pot, mix and slowly heat to 88°F / 31°C:

  1 gallon (4 liters) whole milk, but not ultra-pasteurized or homogenized

  1½ teaspoon (12.3g) citric acid

  ¼ teaspoon (0.7g) lipase powder