Michael: I have been teaching flavor as this sort of sum conception — or, not conception but perception of all of these different influences whether they’re direct influences like taste and retronasal olfaction or trigeminal sense or influences like orthonasal olfaction. Or, what we see when we when we look at a liquid and it’s red and we taste it and it tastes sweeter, right? A university professor said, “Oh, well, I don’t think that’s really right. Flavor is only this limited set of sensory inputs — direct sensory inputs — and all these other things are not part of flavor.” Which, to me, you know… based on readings and conversations with Charles Spence, that’s how I’ve been teaching it — [as] this broader area. And when I talked to him about it again he kind-of said, “Well, all those things are part of… they all change the perception of flavor, but when we use the word ‘flavor,’ it’s a more limited area.” And in my readings of other people, it seems like people have different ideas about if that’s more limited or more broad. And from a practical standpoint, it seems to me that for most people and for recipe developers and food scientists and chefs and even consumers, that’s not a really useful use of the term… if it’s going to be very limited to this scientific definition, right? When we talk about flavor, to me, all of these things are affecting our final perception. So, that should be the term. And if not, then it seems like we need a different term for that — which, sometimes people say “taste” like I did a minute ago. But taste has a very specific meaning as well. So, I would love to hear your thoughts on this — especially having spent all the time you did researching and writing your book on smell. So, please tell me tell me what you think.

Harold: Well, I lean toward, um, what Charles has said, which is that, yes, we’ve come to understand thanks to, 20th, 21st century science that all these different sensory inputs can influence our perception of foods. When you get right down to the experience, you experience the foods. And you don’t experience the influences. The influences are kind of behind the scenes. And what’s center stage are taste and smell and texture and so my inclination is to not to try to define the experience of food with one overarching term And if there’s a desire to do that, I wouldn’t use the word “flavor” in any case, because that is so much more — I mean, historically and common usage both just more limited to the immediate experience of something in your mouth.

Michael: I agree that it’s what you experience when something is in your mouth — and separating what a scientist calls “flavor” and our general use of the term. When we talk about the flavor of something, it definitely includes all those external factors, right? The cross-modal and multisensory perception is part of, … maybe flavor is the wrong word, but it’s part of our perception. When we have food in our mouth, the way that it tastes to us includes all of those factors.

Harold: Sorry, I wouldn’t say “includes,” I would say “is influenced by it.” And those are two very different things.

Michael: You have two identical liquids and one is clear and one has a little red dye in it and the person tastes one and tastes the other and said this one tastes sweeter. That’s because of cross-modal perception, right? So, it’s definitely changing the way you perceive when that food is in your mouth.

Harold: But what I’m trying to say is that’s true in a laboratory setting. In life, you’re just you’re not doing a side by side, right? So, there’s a lot going on when you perceive something, when you experience something. It’s just not clear to me why it’s necessary. In fact, maybe it’s actually confusing to bring in experiences that you’re not having in order to define the experience that you are having.

Michael: Well that’s my point exactly. The experience that you’re having is put together of all of these different inputs, whether they’re direct sensory inputs or they’re external inputs. And so, ultimately, all that matters to the person eating the food is what that food tastes like. And that taste, that final perception is part…. those cross-modal perceptions and other perceptions are part of that final taste for them. So if it’s red and they drink it and to them it’s tastes sweeter because they’ve seen that it’s red, then that’s really all that matters in the end. They don’t have to be in a laboratory tasting two things side by side. And that influences how foods are made, because a manufacturer might make something red specifically so that they can reduce the amount of sugar in it just like they do with vanilla, right? So, if you smell vanilla, then it will taste sweeter to you because of our association of vanilla and sweetness.

Harold: Yeah. What you said just now… that I don’t have any argument with. Maybe this has to do with just the difference between actually sitting down and tasting something, experience…. And, yeah, the language is not helping. —Sitting down and experiencing something in and of itself for itself by itself and not by comparison with other things. It also seems to me that it’s dynamic, right? So, you… something is in your mouth for a second or two. The flavor isn’t constant, right? It’s evolving, and certainly a second or third bite are going to be very different from the first one. It’s really interesting to talk back and forth about these various aspects of the experience of eating and drinking.

Michael: And I’m playing devil’s advocate a little bit here, but the reason is a because I believe that if you’re a scientist and you’re talking about this, then you need a certain set of vocabulary that everyone agrees on and uses the same terms to mean things.

Harold: Mhm.

Michael: For the general public or for people who are trying to learn. Again if they are food scientists or culinologists or chefs or even just the general public who are trying to understand why things taste the way that they do, I think it’s important for them to understand that all these different factors influence it. And I’m going to take just a minute and read this paragraph from Spence where he talks about this. And so even though he has said that you know he reserves the term flavor to mean the specific set of inputs, he says, “However, regardless of one’s position on the question of which senses to be considered as constitutive of flavor, the key point to note is that most people now agree that flavor perception results from the multisensory integration of multiple sensory inputs in the human brain. As if to emphasize the point, Dana Small boldly titled one of her recent review papers, ‘Flavor is in the Brain.’ Hence, if you really want to know why foods and drinks taste the way that they do, then you need to understand something about the underlying neuroscience governing multisensory flavor perception, an area of research that some refer to as ‘neurogastronomy.’” So, you know, in my discussions with him, he’s basically said, “Yes; this is what this term means, but flavor is changed by all these other influences.” So, what the person ends up perceiving is not flavor, not what he’s calling “flavor.” It’s flavor plus all of these other cross-modal and multisensory inputs that ultimately are what the person experiences. And you bring up a really interesting point, which is that if we say flavor is this this limited set of perceptions, and even this may not be… what I’m saying may not even be completely true because of the way our actual receptors work, but assuming that they were not… that they were simpler than they really are, the flavor of a food is the flavor of the food, right? So, you take your first bite and you have a certain perception. And then take your second bite, and it’s a different perception. And the third bite is a different perception. Which is why some chefs will have… you know, like, David Chang likes things to be both under-seasoned and over-seasoned, so that it’s a more interesting experience. And there’s a lot of things that chefs do either with having multiple… you know, like Thomas Keller — multiple small plates rather than eating a big bowl of whatever it is. Or, finding other ways to make the whole meal experience more interesting. So again, it goes back to, I guess … the fundamental question here is, is it useful to have a term that means your actual perception — not just this limited set of inputs which is part of that perception — or, are you arguing that we don’t need that kind of term and we should just… I mean, I think that we need the term because both of us are struggling because we don’t have a word that we want to use. You know, I keep saying “taste,” which would be a good word if it weren’t already being used for something else.

Harold: It seems as though the words flavor and taste are not up to the task of describing and encompassing what we now know about what’s going on in the brain when we experience flavor or taste things. Then, I think, yeah, we do need a different a totally different vocabulary and maybe beginning with an agreement about the about how to delimit what it is that taste means and what it is that flavor means. I think taste, you know, is relatively straightforward, certainly compared to flavor. But I think that’s why I just feel like I’ve got a squirrel running in a cage up here because there are just so many different things going on in trying to pin these things down. You know, from the fact that the experience is subjective but even on the objective side there are so many pieces to it. And so, deciding whether trigeminal counts or whether crunch counts, you know.

Michael: Yeah; there’s all kinds of perceptions, and kokumi is another one, right? So we have… which is not a direct taste sensation, but it happens in our mouth with our receptors. And it’s a metabolic hallucination in our brain, right? So, it’s definitely there. It definitely affects mouth feel and the sort of temporal sensation of foods, but is that part of taste? Is that part of flavor? It’s not a basic taste.

Harold: “Metabolic hallucination…” tell me more about that. I’ve never heard…

Michael: Well, I mean, basically when we have kokumi, the way that our brain interprets this…. [it’s a] sort of like a thickness in the food which is not really there. That’s why it’s a hallucination, right? So,… or the temporal lengthening of how we perceive that food. So with those small peptides, they’re affecting us in a way that our brain…. I mean, ultimately our brain is sensing everything, right? But our five tastes — and maybe, if you include oligustus as a six taste — those have a direct sensory input, right? They have a very clear pathway and how they work and how our brain senses them… just like the trigeminal sense. In any case, there are definitely these perceptions that we have which are not considered to be basic tastes and like I mentioned trigeminal sense is one where we have receptors —like pain receptors, for example. When you have carbonated soda, it’s the enzymes — the carbonic anhydrase is converting it to acid on your tongue, right? And so, that is stimulating our pain receptors, so is that taste is that part of flavor?

Harold: Well, but if it’s turning it into acid, we’re also … it’s also triggering our… still not very well understood acid perception system, right?

Michael: Yeah. And, same thing with saltiness, right? I mean, our salty receptors, ion channels only detect sodium and lithium. So when you have potassium chloride or high doses of sodium chloride, that is triggering this sort of “dirty” salty pathway which also has bitter and sour and trigeminal irritation. Right? So, all those things are part of that. It’s not the salty receptor [per se] but it’s still a salty sense to us. So again, it’s not a basic taste the way that that is defined, but it’s part of our taste perception or our flavor perception. So it’s super complicated, right? There are all these things going on, and as you point out, we don’t still really understand all of them very well, and a lot of very smart scientists are trying to. But for people like me who are trying to teach this to chefs and culinologists and food scientists and just people who want to learn how to cook, I think it is important that we say, “There are these scientific terms and this is what they mean and there are very strict definitions which may change over time as we learn more.” But also, we need to have a general lexicon to use in a broader sense which has some meaning. And we can sort-of muddle through with the language that we have where we’re using terms to mean different things and they’re not very precise. Or, we can say we should call this this and we should call this this and that would be hard to get everyone to agree but that’s why I’m talking to you today because I think it’s an interesting area that’s worth exploring.

Harold: Yeah. No, on that I’m totally in agreement and you know maybe what I don’t quite understand is why? I mean, having read the materials that you sent me or you know mostly read the materials that you sent me I’m just not clear on how a cook in training is going to be helped by going into these kinds of details. I mean, I think they’re fascinating details and you know, I would love to get together with you and Spence and Dana Small and Alex Wiltschko and just you know have a conversation, but in educational materials I’m just not clear on why or in what direction you would be trying to get students thoughts to be moving with discussions like this.

Michael: Well, I can answer that for you very easily. This is definitely something we want to train chefs on, and in fact I’m doing a webinar for the ACF in a few months addressing this very topic because there are a lot of restaurants like Heston Blumenthal’s, for example, and there are a lot of people who have these restaurants that really are working on the forefront of all these perceptions and how they can take advantage of them. And if you look at his book Gastrophysics he [Spence] mentions a lot of things that chefs are doing specifically to alter our perceptions so that we have a better experience or more interesting experience with foods. And some of these are like…. He tells a story, I don’t remember the name of the restaurant where people are… the whole restaurant is all seated together. They all have a prefix meal and all the courses are brought out at the same time. And before anything is brought out, everyone’s sitting around kind-of chatting, waiting for the first course. And there are these little cylinders with a cow on them on the tables. And, inevitably someone will pick one up and turn it over and “Moo!” and they sort-of chuckle. And then someone from another table does. And then pretty much pretty soon everyone in the restaurant is doing this and they’re all laughing and it’s lightened the mood and then they bring out the first course. And so that changes their experience, but it also changes their perception of the foods. And what foods… your memory of your dining experience…. You were telling me once about your experience eating I don’t remember the name of it, but the bird, where you had such sort-of shocking first experience with it and then years later when you had it again it was a very different experience for you. So, restaurant chefs definitely want to take advantage of things like the weight of the silverware, how that affects the way people perceive foods and how they taste. Or, Spence has done research with how the weight of the bowl affects the creaminess perception of it and the richness perception of it even though the food is exactly the same. So, if chefs understand these things, then they can do things to make the dining experience better, to make it more memorable, and to actually improve the way that people perceive the foods that they’re eating. And so I think that’s super important.

Harold: I certainly agree that it’s important for cooks to be thinking about how their foods are going to be experienced. It seems to me that a lot of what Spence is talking about in these sorts of situations are, you know, effects at the margins. It may be that if you’re doing a controlled experiment and people are being very carefully observed and monitored and they’re paying attention to their perceptions, that’s one thing. If you’re sitting in a restaurant talking with people across the table… and, in fact, I have an anecdote along those lines. I went to a multisensory… multimodal… video was being projected onto the table from above… put on by the Roca brothers… it was a small table… it was the El Somni opera dinner, basically. That’s kind of what it felt like. 10 of us all together. Video was being projected on screens around all of us. There was music. The lighting changed. There was a kind-of story being told through the through the food. The Rocas expected — or I think had imagined — that the way we would experience this would be by our focusing our attention completely on the food moment by moment by moment. But we’re 10 people sitting around a table with all this stuff going on. So, of course we’re talking to each other and Joseph the somalier came out and essentially rebuked us and said, “We want you to be paying attention to the food not to each other.” So, which is just you know…. I think it’s true that there are all these really fascinating complications to the experience of eating, and you can do experiments and conceptual things that seem to make a difference and that probably do make a difference one way or the other. But that… in the end people are sitting down at a table with each other paying partial attention to the food. And so, are they going to notice a difference in the viscosity of the soup caused by something else going on at the table?

Michael: I 100% agree with you that that happens a lot that people aren’t paying attention, but that doesn’t…. I used to I used to do a lot of stuff in in video and color science and so forth, and one of my clients was Electronic Arts and I did a lot of work for them and I revamped their whole color system for them because the way that the company’s mindset was on this is: everyone has crappy TVs, so let’s write stuff to the lowest common denominator. And my argument, which it took a while for me to convince them — to change their whole system and their methodology — is why do you want to…. You know, you spent a lot of money and time in in care in producing these products. Why are we dumbing it down to the lowest common denominator? Make it the best that we can so people who care and have the better TVs and color calibrate them and so forth can really experience the best. So, the same thing in food. Just because a lot of people aren’t paying attention or maybe they’re having a dinner party where they’re paying attention to a bite here and there, but mostly it’s the experience…. which also has a lot to do with how much we enjoy the meal, right? If you have a meal with friends, part of it is like the “Provence rose paradox,” right? So, it’s an environment you’re in that’s so important to how much you enjoy and how much you remember it. But that doesn’t mean the food’s not important. And all these effects that have been proven through science to have a real impact on our perception, whatever we call it, are important.

Harold: Yeah; I guess what I’m just saying is that these issues of nomenclature and distinctions among different inputs and the way they’re put together and that kind of thing. They’re, of course, fascinating. I mean, that’s part of the reason I started writing about food in the first place is that it’s the experience of eating and drinking is really interesting and the materials we work with are really interesting and important. I’m just not clear — and of course it’s always fun and interesting to talk about things that are not clear.

Michael: Richard Stevenson, who wrote a book on this, he distinguishes between what he calls distal flavor and proximal flavor. Right? So proximal flavor is flavor as we’re talking about it. Or, the way that that you and Charles Spence like to define it in a more limited way. Right? So that is retronasal taste reception… those inputs that are direct signals that are creating that. And then, distal flavor are the cross-modal … the visual, orthonasal, auditory sense…  all those other things. Charles… one of his early experiments that gave him a lot of recognition was with the Pringles where people had headphones and when the high frequencies were amplified the chips tasted fresher and better to them because of the auditory input while they were chewing that which is multisensory. So, he [Stevenson] uses the term “flavor object” to mean all of these things together: all the perceptions that ultimately are our final perception. And so, you know, maybe that is a term that we just use as an educator when we’re talking about it because, you know, ultimately the term doesn’t really matter, right? If we tell people, “No, this is flavor and this is “whatever…,” their perception, their experience in the restaurant is going to be what it is, right? It’s not going to be any different. But I think it’s important to have a language to talk about these things and especially to say: “These are the things that influence the final perception and here’s why and here’s how we can take advantage of them in food.” Because there’s a lot of decisions and research being made by these food companies in order to make foods most appealing and make the experience the best with them. So, even things like the, the crackle of a chip bag, right, influences your perception when you’re eating it. So, people know this and companies know this. So, I do think it’s important for education that we talk about it. And I just, … my argument is I think that we should have a language that everyone agrees on so that we can have these discussions and have useful terms that people can understand what they encompass.

Harold: Yeah, agreed. (Both laugh)

Michael: Anyway, … but I love your idea of having a panel. I mean, it would be great to get some of these people involved in this discussion and that — me excluded and you included — that’s a great group of people who I think are… have the proper background and are influential and would be great to help sort-of codify some of this.

Harold: Well, no, no. I mean, you included because you’re raising the question in a way that Richard Stevenson and Dana Small and so on and so on are not raising it. You know, they’re coming from their perspective and this is… your perspective is the one that that you know makes the most difference for the most people. So, yeah, but I think it would be it would be fun. Just going to say that we have these conversations… this is the second or third now where I usually quit Zoom and then sit down and think some more. And actually last time then went to your to your documents and you know spent a couple of hours with them, which was great. After this one I’m going to try to remind myself to think more systematically. But I would, by the way, love if you have references for the more recent work on kokumi, any anything that you’ve found helpful in the last few years as you’ve been putting your books together. Those would be great.

Michael: Yeah, happy to send those to you. I appreciate your time and your thoughtfulness about this. So, I’ll send those to you and then we’ll see if we can set up a larger panel because it’d be great to have that discussion with this bigger group of people.

Harold: Yeah. Yeah. Yeah. No, that would be fun. Well, I mean, a lot of them I haven’t seen for a long time, so it’ be fun just to get together and see where people are these days.

Michael: Well, thank you so much, Harold, again, as always. I really appreciate your time and your thoughtfulness and all the things that you have to [make us] think about. So, thank you.

Harold: I wish I did a better job, but I enjoy it.