NEUROENOLOGY How the Brain Creates the Taste of Wine
Gordon M. Shepherd
INTRODUCTION A New Approach to Wine Tasting
There are many books on enology, the field of wine and wine tasting. They describe growing the grapes, producing the wine, marketing the wine under the labels of different vineyards and vintages, and discriminating the tastes of thousands of wines and vintages (for example, Marian Baldy, The University Wine Course: A Wine Appreciation Text and Self Tutorial; Désiré Gautier, Initiation à la degustation des vins; Ronald Jackson, Wine Tasting: A Professional Handbook; Jancis Robinson and Julia Harding, The Oxford Companion to Wine; and Michael Schuster, Essential Winetasting: The Complete Practical Winetasting Course). Anyone seriously interested in wine tasting needs to have some familiarity with the principles explained in these and many other books.
The Taste of Wine Is in the Brain This book builds on these authoritative accounts by focusing on a new approach to wine tasting that can be summed up in the phrase: the taste is not in the wine; the taste is created by the brain of the wine taster. How the brain creates the taste—the flavor—of food and drink is a new field, based on the latest research in neuroscience, biology, psychology, and even anthropology. My own field is sensory physiology, with a focus on smell. Recently, I drew together these new findings in Neurogastronomy: How the Brain Creates Flavor, and Why It Matters, to explain how the mechanics of food in the mouth and molecules in the 1
INTRODUCTION
airway activate the brain to create the flavors of food. The book has appealed to casual readers as well as many chefs and experts in gastronomy and nutrition. There is now an International Society of Neurogastronomy, reflecting the shared goals of many disciplines and communities to better understand food and flavor and their ramifications throughout society. This new approach has engaged people interested in applying these principles to wine. At present, no books focus on how wine taste is created by the brain and the biomechanics of the mouth and respiratory system. Neuroenology: How the Brain Creates the Taste of Wine aims to expand the field of enology to explain this, whether yours is the brain of the casual wine drinker at home or the brain of an expert professional wine taster. A brief introduction was included in a chapter in Neurogastronomy and in a recent article with the same title as this book. Building directly on the principles laid out in Neurogastronomy, Neuroenology explains how the fluid mechanics of the wine in your mouth and the patterns of your breathing activate your sensory and motor pathways to create the taste of wine and, together with your central brain systems for emotion and memory, generate the whole perception of wine pleasure. We show that, just as with creating the flavors of food, creating the flavors of wine engages more of the brain than any other human experience.
A Strategy for Neuroenology Although “neuroenology� is defined as how the brain creates the taste of wine, everything in the brain depends on what is going on with the wine in the mouth, perhaps even more than when we are eating. The movement of a liquid through a physical space in the body is called fluid biomechanics. We therefore adopt a strategy of starting a wine book not with the perception of wine but with the fluid biomechanics of the wine through the mouth and the movement of air through the throat and nose. Once you understand these two movements, it will be much easier to see how they activate the brain to create the wine perception. A second step in this approach is learning that wine tasting depends on structures and muscles that are among the most intricate in the body. Simplified diagrams let you appreciate the amazing ways they function. This will give unique insights into the muscles that move your tongue, 2
A NEW APPROACH TO WINE TASTING
the delicate bone in your throat that anchors tongue muscles and swallowing, the way that sniffing the aroma of wine depends on exquisite control of one of the biggest muscles in your body, and the different muscles that you control consciously and unconsciously. A third step is to explain how much of taste is due to smell—to the molecules released from the wine that are carried to the sense cells in our noses when we breathe out. This is called retronasal smell (retro = backward direction; also called internal smell) because it goes in the opposite direction from breathing in (orthonasal smell; ortho = forward direction). Most wine books recognize the importance of retronasal smell, but there has been very little understanding of how it actually works. Many wine experts on the Internet do not even mention it. We will provide answers to the questions of what exactly retronasal smell is, how it functions, and how it plays the leading role in the taste of wine. Fourth, we will show how taste itself is an illusion. Most books on wine cover the main sensory systems, starting with the sense of taste, and then describe the other senses and how, together with smell, they create what is called the “taste” of the wine. Although it is called “taste” because it seems to be coming from your mouth where the wine is, this is an illusion because we are unaware of the contribution of retronasal smell. The wine molecules stimulating retronasal smell come from both the mouth and the throat. One of the goals of this book is to explain how this taste illusion is created so that the wine experience can be analyzed and enjoyed more fully. Fifth, another illusion is that wine tasting is only a sensory experience. The motor activity you use to move the wine around in your mouth while sampling its internal smell is an essential part of creating the wine taste. This makes wine tasting an active sensation. One of the most important motor actions, swallowing, exposes the wine to the greatest possible extent to internal smell. For most people, swallowing simply clears the mouth for the next drink, but we show how important it is for obtaining the most information possible about the quality of a wine. Finally, this book draws on a lifetime of research, teaching, writing textbooks, and lecturing to diverse audiences on sensory physiology in general and the sense of smell in particular. I especially want to bring together the growing amount of neuroscience research on sensory physiology and flavor as it relates to wine; research that I hope will give exciting new 3
INTRODUCTION
insights into many aspects of the wine experience. The bibliography contains many of these resources.
Creating the taste of wine is a dynamic activity. Stimulation is accompanied by adaptation as the wine taste fades over time; it needs to be kept fresh. Part of this dynamic activity is that, for most of us, wine tasting usually takes place in a social setting, with good company and conversation. Our sensory experience is heavily dependent on our own memories and emotions and those of our companions. All these factors, communicated by language, mean that wine, like most foods, is subject to influence from our environment. We will show that this influence can be so strong that white wines can be judged to be reds and cheap wines judged to be better than expensive ones. The brain plays these tricks, so it pays to know how it accomplishes them. While this covers a consensus of research and practical experience in wine tasting, a number of controversies indicate the need for more progress. They concern how our mouth, respiratory tract, and brain actually interact during wine tasting and how we can improve that interaction. We will point them out as we take up motor, sensory, and central systems and indicate in each section the progress that is being made toward solving them. We tie all this together by breaking wine tasting down into a series of steps, from initially thinking about the wine to the aftermath of swallowing the wine. A unique series of views of the inside of the head and brain will illustrate the steps so that you can see for yourself how the biomechanics of the wine in your mouth and the dynamics of breathing activate the brain systems to create the wine taste. Finally, as we explain these steps, I will relate them to lessons learned from, among others, a great wine taster, Jean-Claude Berrouet, of Petrus and Twomey Cellars. Berrouet was a student of another great wine taster, Emile Peynaud, author of The Taste of Wine: The Art and Science of Wine Appreciation. We will finish with a diary of my tutorial with Jean-Claude. Casual wine drinkers may be interested in how a top quality wine tasting works, and experts may be interested in how one of the greats organized a tasting for a new convert. You will see that resulted in an unforgettable experience on how empirical principles are applied in practice. 4
A NEW APPROACH TO WINE TASTING
In summary, Neuroenology will enlarge your appreciation for how extensively you and your brain are involved in the taste of the wine you drink. I hope you will understand a little better the claim we made at the start: the taste of wine is not in the wine but in your brain. Welcome to a fabulous world of wine: inside your head. To paraphrase the Bard, “Oh brave new world, that has such brain cells in it!�
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