Michael: My guest today is Dr. Harold McGee. Harold’s probably the most respected name in food science. He’s been writing about the science of food and cooking since the 1970s. He’s written four books, including his award-winning On Food and Cooking as well as his most recent book: Nose Dive, which we’ll be diving into a little bit today. His education is in science and literature: he did his undergraduate work at Caltech and earn his PhD in English literature from Yale. He’s a visiting lecturer at Harvard University, and he’s a former colonist for the New York Times. He’s been named Food Writer of the Year by Bon Appétit, and he has been on the Time 100’s list of the World’s Most Influential People. So, thank you for being here, Harold. On Food and Cooking was the first book on food science that I ever read, and I have to say it’s a thing of beauty and a joy forever.

Harold: Well, thank you very much… both for the for the compliment and for quoting the guy I wrote my English thesis about. So, yeah; very kind of you.

Michael: So, I’m thrilled that you’re here. There are so many things that we could talk about, but I want to talk about how we smell — in relation to food, primarily, today. So, smell is difficult, and people — especially if they haven’t been trained — are, a lot of times, intimidated with coffee and chocolate and whiskies and wines and stuff like that because there are so many different scents in them… and being able to distinguish them and name them. And as you know, part of the reason for that is because when we smell those, those inputs basically go into the limbic system, which is a more of a sort-of emotional part of the brain, rather than to the part of the brain where we also have our language center. So, I’m curious, just in terms of sensory training, is part of being able to name scents an important part of being able to recognize individual scent molecules better?

Harold: Yes; short answer. The way I would put it is: the more attention that you can pay to what it is that you’re sensing, the more you’ll able to distinguish and pick up things that before might have been just kind-of a blur, so it’s, in a way, kind-of learning to focus on the experience. And you know, as untrained human beings, that’s a not such an easy thing to do to begin with, because we’re kind-of built, as animals, to take in sensory information and make immediate judgments about whether this is a good thing or a bad thing: you know, “fight or flight” or “things are copasetic.” And it takes a conscious effort to stop and pay attention to a particular sensation and evaluate it. And that’s what we’re doing when we’re developing our senses for flavor: is to slow down, pay attention to what it is that’s going on in our mouths or in our nose and correlate that with what it is that we’ve been doing to the materials: how it is that we’ve been preparing the foods and the kind of impression that we want to make on other people.

Michael: So, when we’re smelling food, for example, there are lots of odor molecules or “volatile” molecules that we’re smelling at the same time. And I’m curious two things: if you’re doing sensory training, is it best to try to find kits like, Le Nez is one that has… they have one for wine, and [one for] whiskey, and [one for] coffee. Or, the Specialty Coffee Association has a guideline for sensory training, and they use common things that you can find at most grocery stores. So is it better to try to find individual scents and train on those? Or if you’re… the second part of the question is: if you’re smelling a complex smell with multiple things, do you smell each of those individually and your brain kind-of puts them together, or will two different smells sort-of form a third smell? So, when you’re smelling them together, you don’t smell them individually, but you’re smelling something else which is a composite of the two?

Harold: Yeah; so it helps to know just a little bit about what’s going on in the brain when we do smell something. As you say, smells are volatile molecules that can escape the foods, go into the air… into our nose, and that’s where we have receptors for smells. And depending on the molecules that come in, different receptors are triggered. And then those receptors send signals to the brain, and then we become conscious of what it is that those molecules were in the first place. The complication is that all that’s happening on a microscopic time scale, and pretty much simultaneously; and so we have to learn to evaluate what’s coming in, knowing that, and knowing that there are lots of molecules involved and that there are lots of… maybe we could call them “preliminary sensations” involved, which our brain then puts together into a composite to make sense and to make a decision: “is this a good thing or a bad thing?” “Should I pay more attention to it or ignore it?” So, the challenge for people who are interested in taste and smell is to reverse engineer the basic overall experience that we have of food and drink and begin to pick apart in our own minds, because that’s where it’s happening: the component aromas; the component sensations that go together to make up that overall sensation. And that takes work. And the best way to go about it and the way that’s done professionally… perfumers, for example, construct aromas from single molecules and learn how to… they begin their training by learning what those individual molecules smell like and learn to be able to recognize them as such. If you’re not a perfumer… if you’re interested in food, then I’ve found the best way to train to develop one’s sense of taste and smell and flavor is simply to taste and smell as many things as possible, paying close attention to what it is that that sensation is associated with. So just taking all the bottles off of your spice shelf and smelling each one of them and registering them and saying, “Ah; yeah. That’s nutmeg, that’s mace.” (It comes from the same seed but it’s a different material, and it has a slightly different aroma.) Just learning by paying attention to the things that are already a part of your life, and from there you can kind of branch out. And if you’re interested in wine or in spirits, then you can learn more about the particular volatile molecules that are found in those materials. You can do that by looking in books or online and getting a general sense and then putting that information together with what it is that you’ve experienced with things in your home and gradually bootstrap your way to a better appreciation for flavor.

Michael: Do you think it’s best to do that with… since… I mean, you mentioned mace or nutmeg which are still multiple molecules… multiple different scent molecules together as opposed to trying to, if you can, get access to an isolated molecule that like vanillin, for example, that you can learn the scent of and then when you smell vanilla you’ll smell that along with all the other molecules that are volatile in vanilla.

Harold: Yeah so the… as you kind-of alluded to, getting access to single molecules is not easy. They have to be either extracted or synthesized, and they come in little brown bottles, and they’re very prone to changes. And, therefore, what starts out as a single molecule ends up actually being several or many more than several. So, in the case of perfumers and professionals, it makes sense to go hunt those things down and pay the premium for them because that’s part of your profession. If you’re trying to learn while you’re being a cook, then I think the best thing to do, at least to begin with, is to start with the materials that you work with every day and then, as you say, you can you can go to the spice part of the grocery store and alongside them you will often find extracts like vanilla extract and almond extract and that kind of thing, which are relatively small numbers of molecules compared to natural vanilla or natural almonds. And so, you can then compare, for example, the smell of an artificial vanilla to a real vanilla bean and begin to understand that, as you say, that there are, with most things, one or a small handful of molecules that are responsible for the overall character of that thing but then they’re always accompanied by a posse of other molecules which kind-of round out that basic identity. So, that’s part of, I think, appreciating food: is to realize that there are materials that have very specific identities to us, but the more you pay attention to them, the more they’re three-dimensional. The more they’re… it’s not just nutmeg, it’s that particular specific aroma, but with other things surrounding it.

Michael: I know you’ve had anosmia, and I do want to talk about that, but I want to start by talking about specific odorant anosmia. Everyone… I mean, probably… has anosmia to some things. And they’re different between different people. So, some people might not be able to smell the predominant molecules in in an apple or, you know,  benzene or different things and so…. I think I heard you (I don’t remember if it was in one of your books or a lecture that you gave) talking about how, through sensory training, we can actually develop the ability to smell a scent. If you could talk about that a little bit more… that’s really fascinating to me.

Harold: Yeah; it’s it is a complicated situation, and we don’t completely understand what’s going on, but there are anecdotal things that kind-of point in the direction of a basic explanation. So, as I mentioned, we have receptors (smell receptors) in our nose that detect molecules in the air, and then the receptors send signals to the brain to become conscious of the fact that those molecules are there. And so, if you don’t have the receptors, then you’re not going to send that signal, and you’re not going to be conscious of that thing being there. And that inability to detect molecules that we know do have aromas is called “anosmia,” which means we can’t smell something. And all of us have about 500 odor receptors, and none of us has the complete set. So, we’re all unable to smell particular things that other people can smell. And it’s just a matter of genetics and so on, and there’s nothing much you can do about that. If you don’t have the receptor, then there’s no signal. However, it’s also apparently the case that you can have the receptors but if our experience doesn’t involve having that molecule that it’s responsive to in our environment, then the body decides, well, we don’t have to make so many of those receptors because it’s really not a significant part of our environment. And so, the body is always making decisions about what to make more of, what to make less of, how to keep things stable… that kind of thing. So, if you’re not detecting the molecule, then the body is not going to be interested in making the receptors. But if you then are exposed to the molecule, the very few receptors that you do have become active. And somehow the body decides, “Ah; this is now an aspect of our environment that is worth knowing about.” So, we’ll make more receptors so that we can become more sensitive. And so, that’s the what’s apparently behind the phenomenon of people being unable to smell something initially but then over time and with exposure they become able to detect it and to become aware of it. So, two different things: one is you just can’t do anything about because it’s basic biology; the other is a matter of exposure and experience changing our sensory machinery in such a way that we become able to detect something.

Michael: All right; so if I can just simplify that…. If we don’t have the gene to make the receptors, we’re never going to smell it. If we can smell it just a teensy bit, then we can develop that, and our body will make more receptors so we can smell it better. And also, if we actively work on smelling it with the receptors that we have, we’ll strengthen the pathways in our brain and, even with a given number of receptors, be able to recognize it and smell it better.

Harold: Yes; and just a side note to that: if you have just a couple of receptors then that may not be enough for you, if you’re exposed to a molecule, for your brain to pay attention and to notice that that aroma is there. And the wonderful practical experience that led to this realization was that there’s a group called the Monell Chemical Senses Center in Philadelphia. It’s a an Institute devoted just to taste and smell. And they give tours, and the tours involve smelling particular things… single molecules in order to help people understand how smell works. One of the docents for those tours was unable to smell one of the those molecules, and so when he gave the tour, he would say, “Here’s this smell… I can’t smell it because I don’t have the receptors for it, but most of you probably can.” After he’d given the tour like 50 times, he became able to smell it. So, it can start out as something that you can absolutely not detect… your brain just does not register it. But you still have a couple of receptors in there that with time can multiply and produce a signal that your brain can then receive and make sense of. So, it’s a pretty amazing transformation when that kind of thing can happen.

Michael: Yeah; it’s really fascinating. One thing that I like to always tell my students, especially if they’re studying in a field that’s not really something that they’re strong in, is: “You work anything and your brain will change, and you’ll get better at being able to learn that thing.” So, I think it’s nice, because smell is something that so many people really have trouble with, just in terms of being a identify individual odorant. So, knowing that that is something that you can work on and develop these pathways and the number of receptors and so forth I think is really encouraging for people who are interested in developing that more. Have you looked at the work… he’s no longer doing this, but you mentioned perfume experts and Luca Turin is someone who’s done a lot of work in perfumes; and for a long time, he was trying to work on the science behind this quantum tunneling idea of how we smell. There’s the shape receptor [model], which you know most of our body works via that way, and then this quantum tunneling idea, which is kind-of fascinating. And it seems like from what I read in his work, neither model is perfect, but some years ago he gave up on it. I talked to him a while back about this, and I’m not sure exactly if it just it was too much of this Sisyphus thing or, you know, the scientific community just wasn’t accepting enough of it, but I’d love to hear what you know and what your thoughts are about that area and how with four or five hundred receptors we can smell 10,000 smells.

Harold: Yeah; well the quantum tunneling theory of olfaction is way above my pay grade when it comes to, at least, what I’m able to make sense of in trying to understand how it is that smell works. As you say, it was controversial from the beginning; it remains so today. I haven’t seen much in the way of publications about it one way or the other for some years now, but I do know someone in the olfaction world who said that the… who told me just kind of anecdotally, or from his overall sense of the field, that there must be more to it than the “Key and Lock Model” of a molecule having a shape and the receptor having a pocket that that shape can fit into and then being triggered in that way. He’s convinced that there’s more to it, but what that “more” is I think is still not completely clear.

Michael: Oh, I’m also convinced there’s more to it, and I know… I’ve looked at some of the studies that were done where they would take a molecule that has a particular odor and then replace hydrogen with deuterium, for example, which has a different… it’s twice as heavy, so it has a different vibration, and that would change the way that it smells. So, just based on that alone. And [in] humans, and they tested with… I don’t remember if it was drosophila (I think it was) and cockroaches and different animals… so there’s definitely something there. I wish there was someone who would do more research in that area because it’s really fascinating and you know the way quantum tunneling works, which we know is a thing… there’s elastic and inelastic quantum tunneling, and it’s pretty well understood. So, maybe it’s something entirely different, but it’s not the “key and lock model” like you say: you know… shape-based entirely. And we also know that there are molecules like benzene, for example… You know, plants create cyanogenic glycosides with a benzene molecule as part of it, and we can smell that as that almond smell even when it’s attached to a larger molecule or thiols is another example… lots of things with thiols attached to them.

Harold: Yeah; in my experience there have always been ways to explain anomalies that don’t involve something… don’t involve a specific theory for what it is that’s going on. But I agree that it’s still unclear, and in a way, it may remain unclear for quite a long time because we’re talking about, on the one hand, the physics of molecule:molecule interactions, and they’re complicated molecules. And then, on the other hand, perception… which is very complicated. The pathway from the receptor to consciousness is just incredibly circuitous and distributed. And so, I have a feeling the result of all these interests and investigations may end up being a just kind of a composite theory where all these different things are involved. Whether any one of them or any 10 of them are involved in a particular perception of a particular thing is up for grabs because… and this is something else to just to keep in mind: I think generally these experiences are fleeting, you know, where the moment we detect a molecule the brain is both noticing that and telling us about it but also adjusting itself so that the attention that it pays to it is modulated by that fact. So the most obvious manifestation of this is adaptation: so, you walk into a kitchen [and] you smell something very strong. Ten minutes later you don’t notice that it’s there because you’ve been in the kitchen, [and] your brain has said, “Yeah; that smell is there, but it’s always there, and I’m interested in telling you what’s changing, so I’m going to ignore it from now on.” So, that’s one aspect of the brain making a decision about what to pay attention to. In a way what we’re trying to do — those of us, like people in the culinary world who are trying to hone their awareness and appreciation of tastes and smells — we’re working against that. We’re trying to use our powers of concentration and focus to override that aspect of our brain and really grab ahold of what is interesting to us and important to us. And those are two conflicting things. So, anyway, it’s part of the reason that taste and smell and flavor are just such rewarding fascinating and frustrating things to deal with.

Michael: Yeah; and the thing you mentioned about us getting used to smells is a super important part of cooking. In culinary school they teach that when you make a sandwich (or whatever), every bite should be like taste the same, which I don’t believe. And one thing… David Chang has a quote… I don’t remember exactly off the top of my head, but basically his philosophy in seasoning (and by “seasoning” I mean “salt”) is that food should be both over-seasoned and under-seasoned, so if you use Maldon salt for example so you’re getting these kind of blasts of saltines, and then you have under-saltiness… so that you’re constantly varying. And if you have something that: every bite tastes the same, there’s this sort of, I don’t know, ennui in eating the whole thing, right? So, it seems like as chefs we would want to be making things that are constantly changing your perceptions and your scents, and so forth, so that it remains to be interesting throughout the eating experience.

Harold: Yeah; yeah. And that’s… I mean, to quote another chef, Thomas Keller, that’s the reason that he moved from traditional three- to five- course meals to tasting menus. Because he said, you know, “After the first couple of bites, I’ve tasted it. I’m not interested anymore. I want something new.” So, of course, on the other side there are you dishes that are traditional… that are deeply satisfying, and you don’t mind taking bite after bite after bite and then asking for seconds. So, yeah; it’s very much up to the individual and what it is that you’re trying to accomplish in a given preparation.

Michael: Yeah; and one thing that Charles Spence talks about in preparing menus is: you know that the first bite is going to be important because that’s that kind-of a blast of flavor perception…. You have a story about eating grouse for the first time, right? where it was just this amazing experience that you remember. But the last bite is the most important in terms of people’s memory of the meal. Most of the meal, they’re not going to remember. They might remember their friends or the environment or the just the general experience, but the actual things that they ate fleet very quickly. So, it seems like as chefs, that’s something that we want to think about is how to make the meal so that the end of the meal is something that really stands out. So, going back to this idea of anosmia, you know… that’s one of the worst fears I think a lot of chefs have, especially in the age of covid where a lot of people did. And I think in your case, it wasn’t Covid-related, is that right?

Harold: Not the first time, but I’ve actually lost my sense of smell three times. The first time was back when I was in the middle of writing my book about smell, and kind-of in the early days, and so this would be, maybe, 2015 or something. And I immediately got in touch with my friends at the Monell Chemical Senses Center, the people who know the most about taste and smell, to ask what was going on. I came down in the morning, I ground my coffee beans in a hand coffee grinder, which I love because I get the smell of the coffee before I’ve even taken a sip, and I noticed I wasn’t smelling it. And then I took a sip of the coffee and I wasn’t tasting coffee. It was just bitter and acid and hot. And they my friends at the Monell said, “Yeah; that happens to people, and we really have no idea why or how, and sometimes it comes back and sometimes it doesn’t. So, we’ve got our fingers crossed for you.” And it fortunately did come back, but it took, like, six weeks. It was quite a while, and I was checking myself every day to see. And then also thinking about alternative book projects, because if I couldn’t smell, then it just wouldn’t make any sense. Anyhow, so anosmia is, I learned, something that’s much more common than I realized at the time. And as you say, Covid really made many more of us conscious of it, because that was an important symptom, and I lost my sense of smell after that first time, and then when I got Covid as well. In both of those cases with a little bit less anxiety, because it had come back once before, and I thought, “Well, maybe this is just my physiology: that a virus will knock those receptors out, and then eventually they do come back.” But, some people have not been that lucky, and some people have experienced what’s called “parosmia,” which is when you smell things, but they’re not the things that you should be smelling. So, you take a sniff of a cup of coffee, and it’s disgusting rather than like coffee. And the upside to these experiences with Covid is the fact that the medical establishment and the research establishment have realized that this has been a badly overlooked aspect of human life, and the funding just has not been there to do the research to understand what’s going on. So, at least now there’s research funding and the beginnings of a little bit of understanding of what’s going on and more attention to treatments before we even understand what’s going on. But, yeah… it’s still a significant problem for many people.

Michael: Did you ever figure out the first time that it happened what caused it?

Harold: I didn’t. I didn’t have obvious symptoms of a cold, but what the Monell people told me was that you can have viral infections and not have a runny nose or cough or fever… anything like that… but the viruses can get in there and cause problems. So, that was their guess.

Michael: Well, it must have been really scary. Probably interesting to you as a scientist after you got your sense of smell back; but glad that that’s over for you. I wanted to ask you also about this concept that I call “osmesis,” which is a play in the word “hormesis.” There are volatiles in foods like butyric acid and isovaleric acid that, in small quantities, contribute in a positive way to the flavor of foods. And those compounds, for example, you’ll find in Parmesan cheese and in butter. But in large quantities, those same compounds smell really horrible: like vomit or armpit smell. And bitterness also is nature’s way of warning us that something that we’re tasting might have alkaloids (or poisons) in it, and so not to eat it. But bitterness is a really important part of the flavor profile of lots of foods, and we as chefs will specifically add bitterness into food to increase that depth of flavor of those foods. So, I’m wondering if you can just take a minute and talk about this concept a little bit.

Harold: As you mentioned at the very beginning, smells are complex mixtures of molecules. We tend to think of smells as, you know, this, that, or the other thing specific. But, in fact, those specific smells are made up of a real crowd of molecules: not all of which, but many of which, actually do contribute something to the overall character. And smells that are dominant can be pleasant or unpleasant, depending on the molecule. Molecules that you find in flowers are often very pleasant and go into perfumes and that kind of thing. One of the molecules that’s unusual in flowers but gives particular flowers a particular quality is this molecule, indole, which is more commonly found in animals and has a kind of animalic quality to it. People disagree about exactly how to describe that, but it’s not pleasant in animals. But a touch of it in a jasmine flower makes jasmine “jasmine.” So, I love the phrase that Ferran Adrià gave years ago when talking about what foods go with what foods. How do we pair ingredients? Are there natural combinations? And his response was to say everything goes with everything. What’s important are the ratios. How much of this and how much of that. So, a little bit of indole in an otherwise floral aroma makes that floral aroma really interesting and memorable. But if it was all indole and just a little bit of floral, then it would be disgusting. And so that’s the case with most of the things that we encounter. The smell of ingredients of all kinds are composites, and they contain molecules that are… the molecules kind-of span the range of qualities. Even in meats, you will find molecules that are more dominant in flowers, for example. But you don’t want meat that smells like a flower. You want meat that smells like meat. And that’s because the balance in meat is very different than the balance in flowers. But, knowing that there is this… there are these shared molecules and qualities across different materials that you might think of as very different, is just really stimulating for thinking about how you can highlight one aspect or another of a of a particular ingredient. So, yeah… I think a great argument for knowing not just about the particular flavors that you find in foods, but knowing about the flavors of the world. Because you can put things together in in a way that’s really personal to you, but also reflective of the possibilities that are out there that you might not otherwise think about.

Michael: Yeah; and there a really fascinating section of your book where you talk about smells of animals and rotting flesh, and so forth. Which, you know… people pay a lot of money to have steak that’s more rotted, right? And there are a relatively few number of aromas in meat than there are in plants. Plants are like scent factories. You know, they use them for all kinds of stuff. So, you know indole is a great example, and you know jasmine is one of my favorite scents. It would be interesting if you could do something where you start with a smell of jasmine and turn up a dial and have some of these other odorants in there until the point where it breaks the scent or where you can really detect that this is now something else.

Harold: Yeah; a couple of things to mention: one is that the Museum of Food and Drink in New York City has had and may still have an exhibition about taste and smell that allows you to do that kind of thing. It’s a machine that they call the “Scent Organ.” So, you can play different keys and hold them down. It’s really worth checking out. So on the subject of indole and flowers…. Years ago, I attended a meeting… this was in the 1990s… one of the International Workshops on Molecular Gastronomy (which gave us that unfortunate term). There was a flavorist from Firmenich, and he was talking about these crossovers between different realms of the natural world and food. And so, he proposed (and someone prepared) a dish of kidneys… I think they were pork kidneys… and jasmine flowers. And his rational had to do with the fact that both had indole. And there would be an interesting kind of crossover between the two; and it was certainly memorable. Some people liked the combination of kidney and jasmine; some people thought it was disgusting. That’s another, of course, whole aspect of this is our personal preferences and experiences and so on. But it was a kind of indication that there’s just a universe out there to explore that has not been captured by particular, set culinary traditions.

Michael: Yeah; that sounds like something Heston Blumenthal would do: having, you know, like a jasmine ice cream.

Harold: Yeah; in fact Heston was not at that meeting, but he came to the following one and got to know this flavorist at Firmenich whose name was François Benzi, and so a year or so after that I I went with Heston to François’ laboratory at Firmenich in Geneva, and we spent the day playing with unusual permutations and combinations of aromas which Heston then put into… I think it was an ice cream. So, anyway; yeah. It’s a wonderful playground for creativity.

Michael: Yeah. So, when we smell food… before we eat it… you know, orthonasally, we’re smelling it in a particular way. And then you’re eating it and chewing it, and the volatiles are coming up retronasally. How do we smell those? How does the brain process those differently from when we’re smelling orthonasally, and is there something more? I mean, obviously we have tastes involved at that time as well, so that’s going to change our perception. But just in terms of the odors themselves, how does our brain processes differently, or do we know that?

Harold: We know a little bit, and the easiest thing to measure is sensitivity. So you know you smell something that you’re holding in front of you… you’re sniffing, bringing air in, and then you take that thing and you put it in your mouth and you chew it and then you breathe out. And it’s the breathing out that brings us the aromas of things in our mouths, so our sensitivity to things that are in front of us, as opposed to things that are in our mouth, is greater by like a factor of ten. We’re much more sensitive. The brain is much more… becomes much more aware of molecules that we smell bringing air in than when we’re breathing out. And that’s keeping concentrations and things like that the same. So, we’re just much more sensitive to aromas (smells) outside of us than aromas in our mouth. The kind of just-so story that you can make up about why that is that if we’re smelling our environment, we’re on the alert for problems. If we’re breathing out something that we’ve already eaten and are in the process of swallowing, we’ve already made that decision that whatever it is okay, and so we don’t have to pay so much attention, and that makes sense. I don’t know if that’s necessarily the whole story, but it’s a way of making sense of those two different two experiences. Then it turns out that, of course, flavor is a combination of taste on the tongue and aromas coming from the food and breathed out through our nose. And it turns out that our brains… because eating is this multi-sensory experience… our brains put together information that it’s getting both from the nose and the tongue. And actually, texture comes into it as well, and chemo-sensation: the irritation of peppers and so on…. The brain’s putting all that stuff together into an overall perception of flavor, and it turns out that in that perception, smells can influence tastes and tastes can influence smells, so that a particular volatile molecule will be more apparent to us under certain circumstances than others, and tastes, the same. So, that’s part of what’s going on when, for example, people try to reduce the levels of salt or of sugar in foods that we want to be supposedly healthier for us… you can do that by manipulating, for example, the aromas. The more vanilla there is in ice cream, the less sugar you need to make it seem sweet. And that kind of thing.

Michael: Yeah; and with anchovies, stuff like that that we associate with saltiness, if we have those aromas, it will taste more salty even with the salt not being there.

Harold: Yeah; yeah. So, the experience of flavor is… it does take in all these different signals and inputs from our senses and then puts them together into a composite. And that’s how we end up being able to influence aspects of flavor — other aspects of flavor than the one that we’re actually changing — when we change a recipe.

Michael: Yeah; and as you know, things that you see, sounds that you hear… you mentioned multi-sensory perception, right? There are a lot of things that get bundled into the sort-of organoleptic properties of food and how we taste them more than just taste and smell. It’s a really fascinating area that’s very complicated. And also, memories; and everyone’s going to have their own field of experience, right? So, even if their receptors were exactly the same, they’re going to experience things, taste them differently.

Harold: Yeah; yeah… exactly. Yeah, there so many different things, many of which I find, anyway, are, in a way, detrimental to the experience of flavor because they’re distractions. You know, that’s one of the reasons that I actually don’t mind if I’m going to a restaurant that I’ve been anticipating… I actually don’t mind going on my own, because so often even with another foodie, I’ve had this experience of going to a restaurant that I’ve been looking [forward] to for a long time…. They’re welcoming me, they ask one of the chefs to come sit with me to explain the dishes, if I want to find out. And I end up not being able to pay enough attention to the food because they’re asking questions. It’s just not socially polite to pay too much attention to your food. And so, you know, the people have found, Charles Spence among them, that things like colors and the sound level in a restaurant and so many different things… music… actually do play with your perception. And on the one hand they’re distractions. On the other hand, they are part of the experience. And so, you know that if you’re the cook trying to create an impression, you have to take that into account and maybe amp up certain aspects of the food in order to overcome the distractions that you know are going to be there.

Michael: Yeah; one of the things that, speaking of Charles Spence, that is really fascinating to me… you talk about sound levels: how if the sound is really loud…. You know, they did all this research on airplanes and airline food. It mutes your ability to taste most of the things that you taste, but amino acids are one that are actually boosted by that, so that’s why tomato drinks are so popular on airplanes because we taste those glutamates more. And so, we’re getting that a sensation of something whereas something else that we might eat on airplane will taste very different from the way it does [normally] because, I mean, of multiple factors: you know, the air is thinner on the airplane and it’s drier and we have the loud engine sounds… But yeah; it’s a really fascinating area. And you know in restaurants…. I mean, most restaurants aren’t even aware, and they tend to be very loud, which is you know… if you’re there with a crowd, it makes it hard to hear anyone. But also, a few of my favorite food experiences of just like…. And I don’t know how much of it is the Provençal Rosé Paradox and how much is just the food was really that good. One of them was: I was doing business in Hawai‘i, and I was there by myself, many years ago, and I had this… it was like a seven-layer poke thing at a very nice restaurant, and it was one of the best things I ever ate. And I was just sitting there by myself with a book which I then put down just savoring it. And it was just really a great experience. And I think if I had been there with a friend or something and we were chatting, probably I would not have enjoyed it so much.

Harold: Yeah; as you’re mentioning that, the one thing that occurs to me that can be wonderful is going to a restaurant with someone in the food world… you know, maybe a chef but not to their restaurant… and with the both of you wanting to focus on what it is that makes this a special place. And then I find it’s kind-of like, you know, a semi-formal wine tasting. You have your initial impression; they have theirs. Because we’re different, we notice somewhat different things, and then we can, in many instances, learn from each other. Say, you know there’s a kind of green pepper note to this to this wine, and I didn’t get it the first time around, but if I go looking for it then I find it. And then, so, yeah… I think there are arguments to be made for both for solo dining and really focusing or dining with a friend who’s as interested as you are in the experience and then sharing that experience.

Michael: Yeah; my daughter is one of the biggest foodies — like, super food-motivated and just loves… you know, she just really savors it. And so… and you know I’m fortunate that my wife and I and our two children are all… not professional cooks but are all good cooks, and we love sharing food together and stuff. But she and I go out often, just the two of us, because we’re both just super into… and that’s exactly like you say… you know, sharing. We always share… we order two things and share them and talk about and analyze and so forth. And that’s really fun to do. And yeah; like you say, it really makes you appreciate something that, you know, maybe she detects something in it that I didn’t pick up at first. It’s like, “Oh yeah; that is in there.” And so, yeah; that’s a great thing if you can find someone to do that with; yeah. I know you’re working on another update it’s been 40 years since On Food and Cooking first came out, so what’s going to be different in this edition, and what we can look forward to?

Harold: Well; so the last update I did was 20 years ago, which is also a long time ago and those have been 20 very active years in the food world from sharing of ingredients across the world to innovations in the kitchen, innovations in equipment, and what cooks can work with. And so, the landscape has changed a lot. And what I’m essentially doing is in each chapter, incrementally taking account of what’s happened in the last 20-odd years. A couple of larger changes… the, perhaps, most significant one is that I’ll have a separate section on fermentation and then more about fermentation in the individual chapters. Because, you know, that’s really exploded in the in the early 2000s. You know, when I first started writing about food, you just didn’t do that kind of thing at home. You know, “microbes are dangerous,” and you need to keep them out as much as possible. So, that’s been a huge change in the in the food world in general. And so… much more about fermentation, much more about perception, because having written about smell, I want to bring that kind of information into each chapter for the particular materials and ingredients that I’m talking about. The structure will be pretty much the same. I’ll be and have been reducing the amount of space devoted to… you could call “classic preparations” or maybe… well, yeah… I think that’s the traditional European preparations… and more time on what’s done in other parts of the world that have become much more visible to us in the last 20 years.

Michael: Yeah; I’m really looking forward to it. As you said, in the last 20 years, so much stuff has exploded and, yeah, fermentation…. I mean, the whole area of the microbiome in terms of health and the probiotics and prebiotics that we eat and how important that is… it’s a fascinating field that has been studied very intently but there’s still so much that we don’t know. And taking advantage of those foods. And it’s so easy to make fermented foods at home… you know, at least some of them. I’ve made natto and things like that which are not difficult but a little more complicated than sauerkraut, but you can make things like that. You know, it’s hard to find natto at a store that’s good, so making it yourself, which isn’t that hard to do, is just such a different experience from buying at an Asian store. So, I really always encourage people to make at least fermented vegetables, because those are very simple or kombucha or something like that.

Harold: Yeah; yeah that’s been just a huge shift in the way people in the field have come to think about food. So, yeah. You have to take that into account.

Michael: Gluten is an area that I hope you address more in the book, because a lot of people are interested in it, whether they’re just trying to bake bread or they’re trying to understand what is it, really, that that people have a sensitivity to. I’m not talking about celiac disease, but just different food sensitivities. And there’s research that that shows that in a lot of those people, it’s not actually the gluten, it’s pentosans or something else that they’re actually reacting to. But for me as a chef and a baker, understanding how the two protein molecules are forming these disulfide and other bonds together…. And there’s a lot that we still don’t really understand, and there’s a lot of conflicting opinions about things.

Harold: Yeah; that’s the just a very basic fact which is that foods are complex systems, and they’re not so easy to understand what’s going on. You can notice effects; you can make correlations; but then actually to pin down: if you do this, this happens for these reasons, then it becomes much, much dicier. And certainly, with protein molecules that are complex in and of themselves, and then interacting with each other and with other components of the wheat seed, yeah. It’s, in a way, standing back from it, not surprising that even in this day and age we really don’t understand exactly what’s going on in a lot of those situations. So, and I just to mention because you mentioned gluten sensitivity and pentosans and so on. The very first edition of my book, which I wrote in the 1970s, had a whole section on food and the body. And in the second edition I dropped it completely, and I have no intention of reinstating it. Because, you know, at each interval the stories are so different that anything that I take months to put together today will be completely out of date in five or 10 years, if not before. So, yeah. I stay away from things like that apart from just maybe recognizing the fact that gluten sensitivity exists; celiac disease exists. But that’s about it.

Michael: Well, very smart. But I would like to learn more about gluten and other high molecular weight molecules that are found in other grains as well and how they interact you know. Well, this has been great! I really appreciate all your time. You know, it’s so wonderful when I get to chat with you about this stuff… it’s just, it’s fascinating. And I just so much appreciate all the time over the years that you put into researching these things and writing about them so clearly for everyone to be able to appreciate and understand.

Harold: Well, thank you very much, Michael. I’m delighted that you’ve found it useful.