Mixing a drink is not rocket science. It does, however, involve a mishmash of chemistry and physics, with a dash or two of biology, all compiled and enhanced with the mixer’s culinary skills. These skills are the tools that bartenders bring to the equation—but the science? That’s where Harold McGee comes in.
Harold McGee is a living bridge between the kitchen and the chem lab. The author of On Food & Cooking: the Science & Lore of the Kitchen, which redefined the field of food science upon its 1984 debut, McGee has written about the science of food and drink for publications with a telling range of titles from Fine Cooking to Physics Today, and is a longtime contributor to The New York Times, where he tackles pressing questions about the chemistry (and physics and biology) of cuisine.
Studying the science of anything requires a certain degree of academic dryness, but over the past three decades, McGee has helped nurture the widespread growth of an enthusiastic culinary curiosity, driven in part by the belief that our food and drink, while keeping us alive, are meant to be enjoyed. “Food and drink do a lot of things for us, and giving us pleasure is right up there,” McGee says. “Flavor has always intrigued me, and I love to know what gives us this pleasure.”
McGee’s experiments over the years have touched virtually every element of the food-production and preparation spectrum, and liquid refreshments are very much a part of his culinary universe. “The great thing about liquid stuff is it really highlights flavor,” he says.
McGee’s work has covered the chemical and flavor differences between hot-brewed and cold-brewed coffee and tea, and various aspects of beer and wine production. Recently, he has played a visible role on the cocktail circuit, appearing at several Tales of the Cocktail sessions in New Orleans and Vancouver, and working with some of the most talented bartenders in New York and London, turning a questioning mind in the direction of the cocktail shaker. “The more you know about what’s in the bean, the leaf or the bottle—and how those molecules got there in the first place, and the processing and artistry of the person who put that flavor in there—that translates in the drink you’re making in your kitchen or your bar,” he says. “That story fascinates me.”
McGee is an unlikely hedonist. Trim and bespectacled, with a serene demeanor, he retains the appearance of the bearded Ivy League academic he was before a twisting career path led him to become a sort of culinary Copernicus—observing, challenging and occasionally debunking long-held beliefs about the way cooking works.
While his name is synonymous with kitchen science, McGee’s initial focus was in philosophy and literature—“I was thinking of studying astronomy, but along the way I decided I was more interested in the ideas than the calculations”—first at the California Institute of Technology and then at Yale University. At first, McGee taught literature and writing at Yale, but tiring of the hamster wheel of academia and the travails of pursuing tenure, he soon found himself following another path. “It occurred to me that I could recoup my longstanding interest in science by writing about it,” he says. “I chose food and cooking as the subject, because nobody was really writing about the science of everyday life, and cooking is something you do every day; if you learn something about it, it could actually change your life.”
Around 2008, McGee was introduced to New York bartender Audrey Saunders through a mutual friend, famed pastry chef Johnny Iuzzini. Saunders, who had recently opened the pioneering cocktail bar Pegu Club, had questions about cocktail preparation that were sufficiently technical in nature to fall under McGee’s bailiwick. Before long, McGee was also working with London bartender Tony Conigliaro, whose experiments with cocktail science in his bar/lab at 69 Colebrooke Row were transforming the drinks world. “I became intrigued by it and started talking with the best in the business, and I was asked some really interesting questions,” McGee says.
Some of these questions proved more difficult than others to answer. One of Saunders’ initial queries regarded the use of egg white in foamy cocktails. The way the aroma of this ingredient affects the way the flavor of the cocktail is perceived is an on ongoing question,” McGee laughs.
Another mystery concerns the reason bottle-aged cocktails—drinks that have been pre-mixed and stored in a glass bottle for days or weeks—taste so different from the same drink prepared immediately before consumption. “There’s an integration of flavor—it’s hard to describe, but the roundness and seamlessness of it is striking,” he says. “I still don’t understand completely what’s going on at the chemical level to make that happen, but it’s clearly a matter of the ingredients reacting with each other in a way we don’t yet understand.”
Other projects were easier to work out. Among the topics McGee has probed behind the bar are the ways carbonation can affect how a drink is experienced. “Carbonation changes the pH of a drink,” as carbon dioxide dissolves and becomes carbonic acid, he says. “Along with the bursting of bubbles, this gives an additional prickle on your tongue—and every time a bubble bursts at the drink’s surface, a mini-jet of liquid is shot into the air, allowing for evaporation of the aroma molecules and greater enhancement of the drink’s aroma.”
Another early project concerned the classic Champagne Cocktail—typically made by pouring Champagne into a glass containing a bitters-soaked sugar cube—and the reason the drink tends to go flat so quickly. “There are compounds in bitters that stabilize bubbles; it’s not that you just explode all the carbonation, but the bitters are making the initial foam last much longer, so you have to wait for it to subside before adding more Champagne,” McGee explains. “Instead, you pour the drink first and then slowly lower the bitters-soaked cube into the glass. Or you can add the bitters separately after the sugar cube.”
Additional experiments have dealt with the way egg-white foam is impacted by using a silver cocktail shaker rather than one made of steel or glass (answer: silver reacts with the egg-white proteins, forming a much longer-lasting foam, though the process can take three times as long); and the reason a lower-alcohol spirit or cocktail seems more aromatic than at higher proof: “The key is the affinity that aroma molecules have for alcohol as opposed to water; the more alcohol in a liquid, the more those aroma molecules want to hang out in the liquid and the less they want to come out into the air,” he says.
While some of the projects seem fairly straightforward, others delve into the murky and sometimes surprising intersection between cocktail chemistry and human physiology. Sugar, for example, obviously functions as a sweetener and affects the viscosity and mouthfeel of a drink, but the way sugar affects our perception of a cocktail is much more complex. “The brain perceives flavor in an integrated kind of way; we analyze flavor into taste sensations and aroma sensations, but the brain takes both of those inputs and synthesizes them into a sensory impression,” McGee says. “When it does that synthesis, one piece of information can influence how much the brain chooses to emphasize the other.” Detecting aroma without flavor, for example, gives a limited amount of information; but accompany the aroma with a taste such as sour or sweet, and the impression of that aroma is much stronger. “Sugar can actually enhance the aroma of a drink by this indirect effect on the way the brain processes the information,” he says.
As with food, McGee sees his drinks-related work not in terms of achieving absolute perfection in a glass, or developing flash-and-dazzle techniques to impress customers. Rather, his aim is more basic: to discover the ways the components in a drink function and interact, and to use this knowledge to make the drink more pleasurable—even if it sometimes goes against conventional wisdom. “Once the blinders get taken off and you realize there are reasons things are the way they are, there become many more ways to make a particular drink,” McGee says. “Just because something is a classic doesn’t mean you can’t look at it carefully, figure out the principles and apply those to other things. Now people are more creative and more proficient in making the classics the best ways they can be made.”
For Tony Conigliaro, McGee has been helpful in explaining and clarifying some aspects of drink preparation that bartenders had reasoned out but didn’t fully understand, such as how to express the fragrant oil from fresh mint without wringing out the plant’s vegetal bitterness, or the reasons sugars and syrups dissolve differently when mixed with alcohol. “He’s the bridge between two worlds,” says Conigliaro. “He understands what we do in the culinary world and the scientific world, and he marries those perfectly.”
Conigliaro says such an accomplishment would be difficult without the manner of serene engagement McGee brings to his work. “He has a wonderful calmness, but it’s not an analytic detachment. He’s always right in the mix, and I love the way he enjoys every part of it. He’s always questioning, and it’s an amazing thing to watch and be a part of.”
Culinary science may have started as a temporary diversion for McGee more than 30 years ago, but he says it’s been amazing to see the blossoming of curiosity about food and drink over the course of his career. “Things have evolved,” McGee says. “For decades, we were indifferent to the details. We ate and drank things and didn’t think about it. Over the past few decades, that’s turned around; now we see food and drink for the fascinating areas they are. We pay more attention in every way, and I feel lucky that I came along at a stage in the history of eating and drinking that this became the case—so I can enjoy it, and make a living at it while it’s happening.”