A Taste for Physics

By John McCormick

WOULD YOU BELIEVE THE way to make a perfect steak every time involves a picnic cooler? Or that you need never again serve overcooked food because guests are an hour, or even a day, late?

Many surprising new cooking ideas and methods were developed by physicists and chemists, not chefs, and I’ll look at several in this article, but a bit of background helps understand why a lot of this is really new despite the fact that cooking has been around since fire was discovered.

When you think about it, cooking hasn’t changed much since prehistoric times. Take a piece of food and apply heat.

Whether you bury potatoes in the hot coals of a campfire, a whole pig under banana leaves, hold meat in flames or off to one side using radiated heat, or cook in clay pots or on the surface of metal pans, little attention has been paid to exactly what happens to the food and how to best control the cooking method.

There have been a few exceptions over the centuries but that is essentially the story until very recently—what little science that was applied to cooking was aimed at commercial applications in factories or fancy eateries.

Then came the introduction of molecular gastronomy or culinary physics.

I was actually in near the end of another cooking transformation, having worked at WGBH in Boston, at the same time Julia Child was making her TV shows.

Today people in the U.S. tend to see fancy cooking as nothing new, but in the early 1960s French cooking with careful attention to sauces, food combinations, and using the best ingredients was highly innovative, except in a very few authentic French restaurants.

Home cooking in the French culinary style was something revolutionary, and entirely due to Julia.

A similar revolution is taking place today, commercially and in home kitchens with the introduction of more new ideas and even newer appliances.

I grew up around commercial cooking in a hotel my parents managed and went on to college where roommates found that doing all the dishes was a small price to pay for my doing all the cooking. I have had a serious interest in cooking for a long time—when is the last time you baked fresh bread?

While making bread is still a bit of an art, one I practice almost daily, we are on the threshold of a major evolution in food preparation where cooking techniques are based on science, not mere guesses or mere tradition.

[Triple loaf French bread pan, shown at left.]

This sea change in the kitchen has been slowly developing. Occasionally real scientists have explored cooking on a laboratory basis. Count Rumford (Sir Benjamin Thompson), for instance, investigated slow cooking of large meat chunks, back about the time of the American Revolution.

There were some other early experimenters but most were working on ways to improve food preservation or commercial cooking, not something a home cook would be able to replicate.

Today there are PBS shows, “Cook’s Country” and “America’s Test Kitchen,” that don’t scare away viewers by using terms such as molecular gastronomy but that definitely take a scientific or semi-scientific approach to cooking, experimenting with different cooking methods and ingredients.

Although most home cooks won’t be buying centrifuges or a Dewar flask to store their four liters of liquid nitrogen, many tools of molecular gastronomy are already in a well-equipped kitchen, for example, an immersion blender. But today’s serious home cook should consider adding an ice cream maker and a water bath, the temperature of which can be controlled to one degree or less for days at a time.

A foodie who can’t produce pea butter in a home centrifuge may be forgiven, but the ability to serve a well-cooked steak or savory frozen dessert is essential. Molecular gastronomy is already moving from the laboratory into the home.

Kidding aside, modernist cooking doesn’t need to be complicated to be amazing and, like physics, you can read about the results and take advantage of this new branch of culinary science without becoming a researcher yourself. You don’t need to work at CERN to enjoy learning about their work, and the same goes for the new food science. You can stand on the shoulders of culinary giants.

The new culinary science is based on hard science. Trained physicists and chemists with a love for food are dissecting every step of the cooking process, testing different ways of cooking and in the process are turning the traditional kitchen arts upside down.

If you have any doubts, just recall that one of the best known of the new food scientists worked at Microsoft as chief technologist, Nathan Myhrvold. One of his contributions has been to photograph and describe the condition of an egg white and yolk at 4 degree intervals from 132 F (pasteurized but otherwise raw looking) to 194 F (with rubbery white and “powdery” yolk with the dreaded green coating).

My Introduction to the New Science

It shouldn’t come as a big surprise to those who know I am a trained physicist myself (with a year of chemistry you can blame Harvard for), to learn that many of the tools and techniques involved in molecular gastronomy are nothing new to me. I’ve been using a propane torch in the kitchen and was making the best instant coffee at home decades ago.

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“A note on instant coffee: because heating coffee beans and their essential oils too much makes it bitter, try adding a pound of coffee to a gallon of pure water, let it sit a day, then filter it. The coffee concentrate can be used like instant dried coffee but you, not Folgers, control the blend you use, from Coffee Anyone’s San Francisco Vice to kona, or real blue mountain (part of God’s Blessing according to Spider Robinson—i.e. black blue mountain with a dollop of Irish).”

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As with many discoveries in science, one of my own cooking discoveries was the result of an accident. I was making French fries and dumped the raw potatoes in the pot of oil without noticing that the burner had been turned off by someone else.

What can you do with cold potatoes absolutely drenched in cold peanut oil?

What I did was turn on the burner and bring the whole mess up to normal French fry temperature.

To my surprise they were perfectly fried and not greasy at all, not what you would expect from the vast lore of cooking.

Everyone knows that to get a good fried potato you need a deep fryer that really maintains a high but not too high heat. Many cooking shows tell you that and often test to see which best maintains the correct temperature, but physics says the only real way to keep your oil temperature near the optimal temperature is to have a lot of oil compared to the volume of potatoes.

Anything else and you will get soggy French fries soaked with oil.

Or, so the tradition goes.

Now I knew different, but why?

Did you ever think about the logic and science behind the teaching that potatoes will absorb a lot of oil if the temperature isn’t high enough?

Cut a raw potato. in a few seconds it will be wet with the water oozing out of the interior. Of course, raw potato is mostly water, and what do we all know about oil and water? Right! They don’t mix.

So, just why would a fresh cut raw potential French fry absorb oil?

The answer is simple; it wouldn’t, which led me to repeat the accidental experiment—I put a batch of French fry cut raw potatoes in a pan of room temperature oil and brought it up to frying temperature.

This reduced the risk of splashing oil almost to zero, making it much safer than dumping wet food into hot oil. It also meant I didn’t need to use the “best” deep fryer because the potatoes and oil were heating together. The second try with cold oil again produced perfectly cooked French fries with crisp outsides and meaty, but not oily, interiors.

That is molecular gastronomy at its most basic, the simple application of science and logic to the process of cooking. In fact, some chefs prefer the term “culinary physics.”

Cooking with Steel

If you are a big pizza eater, you either have made or someday will try making your own pizza at home. It isn’t difficult, nor expensive, and not only do you have maximum control over the ingredients, your only worry about the cheese won’t be whether it has gone gummy, or if the delivery guy licked your pizza because he felt under-tipped last week. Instead, you will worry about how long you have to wait before it is safe to bite into the oven-hot pie.

Those who make their own bread often try making pizza and after a few disappointing pies baked in a normal oven on a cooking sheet they invest in what they are told are the two essential tools for home pizza makers.

Whether you have a gas or an electric oven, you have to put the dough onto a baking pan, cookie tray or special pizza pan of some sort. That pretty much guarantees soggy pizza from the get go, so you have to avoid the pan altogether. Even a perforated pizza pan I have is less than ideal.

The first essential to make a home pizza is a peel, the large wooden paddle that lets you slide a decent sized pie into and also out of a hot oven. Get one, and get wood, not some plastic version. It will prove perfect for getting lots of things in and out of a hot oven, including cookie sheets and French bread molds.

[Great Northern Popcorn 2-1/2-Ounce Red Tabletop Retro Style Compact Popcorn Popper Machine with Removable Tray, shown at right.]

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“You can’t make good French bread without curved and perforated cooking sheets/pans. If the dough is soft enough to bake properly, it will flatten out on a cookie sheet or any flat cooking surface. Amazon carries them.”

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The second essential is a pizza stone, or a set of oven bricks. The stone is intended to provide even, high heat to the pizza and serve as a baking surface. At the same time stone or fire bricks will retain heat normally lost when you open the oven door. That is simple science for which you don’t need an “A” in thermodynamics. (I got a “B.”)

But when you analyze this from the viewpoint of a physicist or engineer, it really doesn’t make much sense to use a stone. Stone is traditional; that is to say, when ovens were built a thousand or two thousand years ago, they weren't made of enameled metal, they were built of stone. Stone simply doesn’t conduct heat very well, at least not compared to some other materials—that makes it great for the outside of an oven, but not particularly good as a cooking surface.

Metal is a far better conductor so doesn’t it make a lot more sense to use a big chunk of iron or steel as a baking surface? It will be virtually indestructible and certainly can retain a lot of heat. Being highly conductive it will give up that heat very quickly and evenly when it contacts anything—such as a pizza.

This is exactly the sort of reasoning that led some scientists to begin looking at all aspects of cooking, not just from the standpoint of taste or food safety, but whether, at the very most basic level, cooking is still stuck in the Dark Ages.

I have made my own pizza for decades in part because, in many places, I have lived there was no delivery service, but I also do it so I can vary the dough and use combinations of toppings never heard of at Pizza Hut. I make my own dough; it only takes a few minutes of my time with a mixer, so I can choose sourdough, plain, rye, whole wheat, white flour dough with almond flour and oat bran added, etc. This also takes a bit of science because many combinations won’t rise—you need to add vital wheat gluten to get a decent risen crust.

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“I want to put in a word here for Bob’s Red Mill, a specialty food company you see given a very small shelf space in most supermarkets. Bob’s carries many essentials for molecular gastronomy from the above-mentioned gluten and almond or hazelnut flour to xanthan gum, essential for thickening many sauces and other liquids (as well as gas well fracking fluid).”

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Being unhappy with results from a pizza stone, I was about to buy a used commercial pizza oven when I ran across a specially produced “baking” steel from Baking Steel, 16 in. x 14 in. x ¼ in. and about 15 pounds, with a good baking surface and pre-seasoned. (There is also a ½ inch thick version tipping the scale at a hefty 30 pounds.)

Turning up the oven heat to the highest setting, by the time pizza dough taken from the fridge warms enough to press, roll, or, for the truly adventurous (or mildly intoxicated) throw into your favorite thickness, the steel is hot and it does a terrific job, virtually indistinguishable from what you can produce in a real pizza oven.

Steak your Claim

Another application of pure science to kitchen or outdoor cooking addresses the eternal problem of producing a perfectly cooked steak, pink inside but with just enough charring to give it a mouthwatering appeal (produced by the Maillard effect).

Over the years I’ve heard many ideas for producing a great steak, ranging from freezing it solid so you can get a good char without overcooking the inside, to various cooking techniques such as using a heavy cast iron pan instead of a home broiler—the baking steel would work too.

But as a scientist I looked at the problem starting with the basics.

No matter how you go about cooking a steak, the simple fact is that except for the very outer edge your fine steak isn’t grilled or broiled, or pan fried, or even chicken-fried—e.g., battered and deep-fried.

No, most of your steak is simply steamed. Any attempt to cook a perfect steak has to begin with that basic fact, and that means you can essentially ignore all the advice about using pans, broilers, charcoal, and so on.

Your steak will be steamed using any of those methods, so concentrate on the ultimate goal. What you really want is an evenly cooked piece of meat with the surface charring necessary to achieve the taste you get from the Maillard effect—the process that produces most of the flavor not found in raw meat.

That leads us to one of the main innovations of modernist cuisine, Sous-Vide or airless/vacuum cooking, which offers an easy method of making a perfect steak using complex tools such as a propane torch and an ice chest. We’ll start with the place of a blow torch in the kitchen—it isn’t just for sweating the copper pipes under the sink.

Every Kitchen Needs A Blow Torch

Julia Child is infamous for having introduced an important new kitchen gadget, the propane torch, to the home cook’s list of essential tools.

This was a big break for men trying to think up wedding gifts because instead of giving the fifth never-to-be-used chafing dish or, 20 years ago, yet another fondue pot, one could give hardware! A box of rare tool bits for those honey-do jobs to the groom and a fancy-looking torch to the bride.

I recall one show where Julia actually flourished an old-fashioned blow torch, the gasoline-fired kind, but that was an over the top joke— the kind she loved. Knowing her background which included both Cordon Bleu training and a stint working for Wild Bill Donovan (founder of the CIA), using a blowtorch to make creme brule was no surprise.

She brought traditional French culinary skills to the U.S. but Julia was also innovative and applied both common sense and a knowledge of science to her cooking.

Why, she thought, make cooking more difficult than necessary? The famous French dessert, crème brûlée, is essentially a cold pudding covered with melted brown sugar.

The French way to make this dish is to carefully heat the egg mixture until it jells, chill the resulting custard in small oven proof dishes (ramekins), place them in a cold water bath, sprinkle brown sugar on top, then slip them under a broiler and hope the sugar melts without burning and without heating up enough to turn the custard back into a liquid.

Today, thanks in great part to Julia, virtually every real cook knows that you simply make the custard, spread the brown sugar on the cool pudding, then whip out a propane, butane, or MAPP torch to melt the sugar in a few seconds without ever exposing the custard to oven heat.

Molecular gastronomy, or modernist cooking, just takes this one step further by using a torch to apply the final browning touch to every cut of beef from steak to roasts.

Sous-Vide, the Path to Perfect Food

A perfect steak. Well-cooked vegetables. Eggs just the way you like them. An end to disappointment when guests arrive late or your meal is delayed due to poor planning or a surprisingly tough piece of meat—all that is what Sous-Vide promises.

Ever wished you could make a perfect steak or hamburger a day ahead so you knew the dinner party or grilling event would be a big success and you could relax with the guests?

Or have you given any thought to all those wonderful smelling juices you drain out of a roasting or broiling pan? The French solution is to make a sauce with the food, but it doesn’t work when grilling so why not keep all that flavor and moisture in the food to begin with, instead of trying to reconstruct the flavor with a heavy sauce?

That is the goal of airless cooking or Sous-Vide, the absolute core cooking technique that separates modernist/molecular gastronomy from traditional cooking.

Essentially this is just slow cooking, but no crockpot ever turned out such succulent foods.

The basics are simple: put food in a Ziploc bag and squeeze out all the air, or use a vacuum sealer to encase the food in an airless package.

Now drop this bag into a water bath, either preheated or one you bring up to a perfect temperature, such as 131 degrees F—the food safety temperature that pasteurizes the food.

At that temperature eggs won’t even begin to cook and beef is on the very rare side, but both are safe to eat as long as you wait long enough to bring the internal temperature up to that same point.

The goal of Sous-Vide cooking is to get the entire piece of food to the same temperature all the way through, a temperature that makes your meat exactly rare or perhaps medium rare, or your scrambled eggs just the right consistency.

What makes this so different is that, unlike, say, frying, all the food is cooked perfectly to the same degree.

This water bath cooking can continue for days after you bring the food temperature above that magic 131 degree F level, which makes it safe. A good thing since days are what it will take to tenderize some thick cuts of meat.

Try this in your kitchen just with a pot on the stove and an accurate thermometer—I found I could cook burger patties in a two-quart saucepan on my electric burner with it adjusted just right and the pan off to the side a bit.

I thought this would be the perfect use for my inexpensive induction hot plate, as it already displays both wattage and temperature.

An induction hot plate or stove, works only with steel pans because the heat is generated in the metal by a varying magnetic field, not in the glass-surface "burner" itself.

Unfortunately, although I love the new hot plate and it does change temperatures as fast as a gas range, the temperature simply isn’t accurate in cheap models. To get perfect temperature control you have to spend about $500 on a single hotplate—a water bath cooker of some sort will be a better investment than a really expensive induction hotplate.

As far as mine goes it only took the most basic knowledge of science to test it. Putting a digital food thermometer between the pan and the cooktop I found the same temperature whether it was set at 120 degrees or 180 degrees (and, yes, I did check that the probe was non-magnetic).

For Sous-Vide cooking at the most simple, you can just bring a large water bath to the right temperature with the food in it, adjusting carefully by adding hot or cold water until the food is about the right temperature, then relying on the thermal inertia of a large volume of water.

A good example of this is to seal up some steaks, fill a travel cooler, and bring everything up to the desired temperature, say 135 degrees F, close the lid, put it in your car, and head off for that grilling party.

When you open the steaks a few hours later they will be perfectly cooked all the way through—all you need is a hot grill to induce the Maillard (browning) reaction and add some color to the meat. In a pinch, as a flourish, or perhaps out of sight, you can also whip out that faithful propane torch and apply just the perfect searing to sides and the edge fat.

Using a torch you can sear the flat sides evenly and cook the edge fat varying amounts depending on the thickness, not something you can readily do any other way. The interior of the steak itself is already at the perfect temperature.

In commercial kitchens this water bath cooking is becoming very popular because the food can be kept safe yet ready to serve all day, and every customer will get exactly the same perfectly cooked food.

In the home kitchen vacuum sealing and water bath cooking serve the same purpose as the venerable crockpot but without wringing all the moisture and most of the flavor out of the food—crockpot cooking generally requires what would normally be serious over-spicing to get any flavor in the foods. Use it for stew or tomato sauce, not to cook large pieces of meat.

Early adopters of this cooking technique took the risky path of buying used lab equipment on eBay and trying to get it clean enough to be food safe, but even with vacuum sealed food this was tricky and a bit dangerous; you never knew what those crazy scientists had been heating, or why. If the equipment worked perfectly, it was for sale.

Today you can do what I did. Go to Amazon and order a $450 Sous-Vide SVK-1000 water bath home cooker with one degree control from 86 degrees F to 210 degrees F and a 99 hour timer. Sounds extravagant, but not for a new cooking technique that only uses about 60 watts to cook food. Compared to any quality traditional oven, this water bath oven is reasonably priced, since you can use it every day.

To experiment or just to save money you can also find extremely accurate temperature controls that can be plugged in between your crockpot and the wall socket, or make one from scratch with a PID (proportional-integral-derivative) controller such as a $100 DorkFood DSV temperature control and an inexpensive immersion heater.

Plug them together and you can make a small or large water bath oven for less than the cost of a single good kitchen knife or quality saucepan.

Tools

Steel—a heavy baking steel, which in the oven maintains heat and produces the most perfect bread and pizza, when taken from the freezer doubles as an anti-grill that cools and solidifies foods almost instantly. It is said you can also use it as a griddle when placed on an induction burner but in my experience you are a lot better off buying a highly rated griddle.

Torch—an inexpensive propane torch with flare fitting or use a MAPP gas bottle instead. Small butane torches work well for crème brûlée.

Ice cream maker—the expensive kind [shown below right] that includes its own freezer. You can buy ice cream at a store, but making it at home means you can use fresh ingredients and unusual spices such as a touch of cayenne pepper, freeze dried coffee, Ovaltine malt, almond milk and heavy cream for a frozen chocolate delight.

The richest ice cream is possible using heavy cream with fresh peach pieces, but so is a light sorbet made from grapefruit juice, or a frozen milk-like ice made from almond milk with real added almond or almond flour.

Of all the useless appliances I have collecting dust in my kitchen, you would think an ice cream maker would be at the top of the list. When all I need to do is pour in a few liquid ingredients of almost any kind, including booze if desired (yes, that is probably how Dr. House got vodka flavored ice cream for a bachelor party), flip a switch, and have a frozen desert a half hour later. I found I was making ice cream, sorbet, or some variant almost every night.

Any cook will recognize the freedom of knowing it takes only a minute or two to start a fine dessert that will be ready when dinner is on the table after what is usually about a typical 20-30 minute dinner prep time.

By comparison my freeze-ahead maker almost never saw use.

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“A word of warning; although I cook every day and have since far back into the last century, I wasn’t prepared for how liberating it was to make use of modernist cuisine techniques every day—I gained 10 pounds in 30 days.”

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Infuser—this is how you make pancakes without baking soda or powder, the way you create a hundred unusual textures in foods that never before had tiny bubbles in them, and even how you create some infusions where the pressurized gas is used to facilitate mixing of unusual ingredients. The basic ISI infuser will cost about $50 and the first thing you will use it for is to make whipped cream—just pour in cold cream, screw on a nitrogen cartridge, shake, and dispense whipped cream.

The next batch will, I guarantee, include some enhancement—I tried maple syrup and it worked great. But, so did a mix of milk, liquid chocolate sauce, Splenda sweetener and vanilla extract. There are few things you can find premixed in a can on the supermarket shelf and even the whipped cream includes ingredients not needed when you use ultra pasteurized cream and an infuser.

The infuser also dispenses things such as sous-vide prepared scrambled eggs—texture is an important component.

Advanced Tools

For those with some solid experience in a chemistry lab, you might include a centrifuge, a Dewar flask to store your liquid nitrogen, a selection of enzymes and other chemical compounds, and a good syringe to inject things such as savory liquids in meat or poultry or rum into a mincemeat pie.

The water oven I’ve already described is a really critical kitchen tool for modernist cuisine, even more important than the self-contained ice cream maker, but probably not more important than the infuser/foamer. This really is a useful and very practical gadget for the home cook, even the macho steak and potatoes type.

Homework

I urge you to do a bit of experimenting on your own.

An inexpensive introduction to the new science from one of the pioneers is Herve This’ “Molecular Gastronomy, Exploring the Science of Flavor.” Short pithy chapters explain why chocolate gets that white coating, how to keep bread fresh, and dispel many cooking myths.

If this article or the This book whets your appetite, so to speak, you need “Modernist Cuisine at Home.”

Nathan Mythrvold and Maxime Bilet have been big movers in this field with their massive and beautiful books that dissect every aspect of cooking from showing what a one degree temperature change can do to an egg, to slicing an oven in half.

For a practical start in this field using techniques you can apply in almost any home kitchen, I strongly recommend you get the $120 “Modernist Cuisine at Home” that includes a kitchen-safe spiral-bound cook book and a beautiful textbook explaining the science behind procedures that can be quite exacting, such as the advice to salt hamburger patties exactly one hour before cooking. This two-book set includes 456 pages and weighs in at 12 pounds, including the heavy slip case.

Add Chris Young to the team of authors and you get what is perhaps the most important cooking book since “Larousse Gastronomic” and the most influential since “Mastering the Art of French Cooking” emerged—the $600 2,438-page, 50-plus pound set of “Modernist Cooking: the Art and Science of Cooking.” Be aware that although it also teaches a lot about cooking and science, it is expensive because it is also a work of art.

Dr. Myhrvold was the first chief technology officer for Microsoft (but I don’t hold Windows against him too much) and has a degree in theoretical physics from Princeton along with other degrees. He also worked on quantum gravity with Stephen Hawking.

Although he didn’t found the new cooking science, his contributions have been enormous, although producing the beautiful “Modernist Cuisine” alone would be a major contribution to the field.

I see this is already a very long article and I have barely touched the surface of this fascinating approach to cooking. I left out things such as how to cook a perfect sunnyside up egg—I’ll never bother because you have to cook the yolk and white separately then reassemble them. I think that is carrying things too far, but there are many simple and practical cooking techniques developed by these scientists.

If you care about what you eat then why not apply real science to what you make at home? Fast food companies spend millions every year on the science of making food fast, cheap, and addictive. Molecular gastronomy puts the same effort into home cooking. 

Further Reading

“Modernist Cuisine at Home,” Nathan Myhrvold and Maxime Bilet, The Cooking Lab. For anyone.

“Modernist Cuisine: The Art and Science of Cooking,” Nathan Myhrvold, Chris Young, Maxime Bilet, The Cooking Lab.

“Molecular Gastronomy Exploring the Science of Flavor,” Herve This, Columbia University Press.

“Under Pressure: Cooking Sous Vide,” Thomas Keller, Artisan. For professionals only!

“Mastering the Art of French Cooking” (2 Volume Set), Julia Child, Louisette Bertholle and Simone Beck, Knopf.

“Larousse Gastronomique: The World's Greatest Culinary Encyclopedia,” Completely Revised and Updated, Librairie Larousse.

John McCormick has been a rancher, mechanic, radiologic monitor, and an emergency management coordinator. He is a trained physicist, science/technology journalist, and widely-published author with more than 17,000 bylines to his credit. He is a member of The National Press Club and the AAAS. His full bibliography is online.