(De)constructing flavours

… and in breaking news, chocolate flavour and vanilla flavour are different from one another. But what actually makes flavours different? Clearly, both of these flavours are sweet, so we recognize that the non-sweet bit – the inherent chocolaty-ness or vanilla-ness – is the essential difference. And these qualities are, of course, due to volatiles – in other words, they are smells, perceived via the retronasal (back of the mouth) route to our smell receptors in the nose. So, clearly flavours are combinations of smells and tastes.

But what about other sensory information? If we wanted to accurately describe the flavour of a curry we’d also no doubt also say the flavour is hot or spicy; similarly, the flavour of Coca-Cola is fizzy and that of vodka has ‘bite’. The inclusion of this type of sensory information in our definition of flavours is not especially controversial – after all, a curry without the spiciness seems not a curry at all. More to the point, our mouths contain endings of the trigeminal nerve that are responsible for picking up those chemical signals that lead to perceptions of chemical heat, temperature, and sensations of dryness, prickliness and bite. These same nerve endings may also contribute to the experience of taste.

Stepping outside the mouth though, we are confronted with vast quantities of sensory information that contributes to our experience of a food’s sensory properties. Several overviews in recent years have discussed the importance of vision, hearing, and touch (outside the mouth) in influencing our perceptions of what goes on in the mouth during eating [1, 2](see also previous posting). In a new book by Spence and Piqueras-Fiszman [3], the recent research on the impact of properties like colour, shape and weight in the cutlery, crockery and physical environment of food perceptions and preferences are detailed. Does that mean each of these influences must be included within our definition of flavour?

Some researchers do, in fact, suggest this. They propose, for example, that food features such as crunchiness, the result of both sounds and feedback from pressure sensors in the teeth and gums, are intrinsic to the flavour of some foods. Previously, I discussed the role of expectations – essentially the product of our memory for what belongs with what – as another important influence on flavour experiences. So, potentially, if we wished to be broad enough, flavours could be perceptions involving multiple near and far senses, as well as input from memories. Suddenly, the mouth and what goes on inside it becomes only part of our concept of flavours.

Does it really matter how broadly we define flavours? We can distinguish between the sound of an orchestra and the impact that the acoustics and seat comfort of the hall in which it is heard have on our experience of the music. Similarly, there are good reasons to divide our food experiences into mouth-based sensations, on the one hand, and other sensory information that impinge on our perception or enjoyment of these sensations, on the other. Thus, we are able to experience flavours without any input from any senses except smell and taste. To be chocolate flavour, a little square of fat, sugar and miscellaneous odour compounds does not require the colour brown, or even the sensation of melting, but it does require chocolate aroma and sweet taste in all cases.

Recent studies of the brain’s processing of smell and taste have identified a network of neural structures that appears to encode for flavour, as distinct from odours and tastes separately [4]. Indeed, the brain appears to process the same odour differently, depending on whether it is experienced in the mouth as part of a flavour or external to the mouth, when sniffed. The brain is fundamentally a processor of multisensory signals, largely because integration of different sources of sensory information is biologically useful. An important question, though, relates to the adaptive significance of the ‘construction’ of flavours – why do discrete neural circuits, for example, represent flavours rather than simply odours and tastes separately? It is generally proposed that, in the case of foods, it is the combination of tastes and odours together that reliably tell us whether an object is a food that is fit to eat. However, it is clearly not only about identifying foods. While it can be argued that it is taste and odour together that allow us recognize pear as a pear, in practice, once it is familiar the pear odour is sufficient. In a world without taste, trial and error would allow one to distinguish pears from apples and could even tell you whether or not pears were safe to eat.

The most important consequence of integrating odours and tastes may be primarily about pleasure. From the perspective of food preferences, flavours seem to be fundamental units. This is because, at birth (or in the case of salt, shortly thereafter), we are hedonically inflexible when it comes to basic tastes – sweet, sour, salty, bitter, umami. Our likes and dislikes appear to be pre-set as an adaptive mechanism to ensure intake of nutrients (sweetness, saltiness, umami) and avoid toxins or otherwise harmful substances (bitterness, sourness). On the other hand, there is little evidence that odour preferences are other than the result of experience, a process that may begin in the womb.

Repeatedly experiencing odours with tastes attaches additional meaning to the odour that is primarily hedonic, that is, pleasure-related. The pear flavour that is not bitter, not too sour, and quite sweet provides pleasure in the eating. In other words, we are motivated to consume it because of its sweet taste and the prior associations with the calories that the sweetness, and subsequently (through repeated experience), that the pear flavour itself signals. And, of course, this occurs even prior to eating: pear odour repeatedly paired with a sweet taste itself becomes pleasant.

The perceptual consequences of integration of odours and tastes can be interpreted in the same way. The well-known phenomena of food odours being described in terms of tastes – the sweet smell of vanilla or the sour smell of vinegar – also arise from the repeated pairing of the odour with a taste, sweetness or sourness, respectively. But, these perceptual qualities also have hedonic consequences: sweet-smelling odours are pleasant and this quality may in itself motivate consumption even if we cannot identify the actual odour or its source. Conversely, something with a bitter or sour smelling odour is unlikely to be eaten, especially if we cannot recognize the odour. As such, these perceptual changes to odours may help compensate for the fact that odour identification is particularly difficult even for common foods.

Hence, the key purpose of odour/taste integration is not that it aids identification per se (although it might), but rather that it gives an hedonic value to the flavour, which crucially it the defining characteristic of the food. Thus, flavours can be most accurately seen as “objects” constructed for their hedonic qualities. Initial, “gut” responses to foods are almost always hedonic, and this naturally precedes accepting or rejecting the food. Thus, what we perceive when we sit down to dinner are, thankfully, integrated pleasure-inducing perceptions – spaghetti al pomodoro and a nice Chianti – rather than a collection of independent, hedonically-diverse tastes, odours and textures.

                                                                                                                       

1.         Delwiche, J., The impact of perceptual interactions on perceived flavor. Food Qual Pref, 2004. 15(2): p. 137-146.

2.         Prescott, J. and R.J. Stevenson, Chemosensory Integration and the Perception of Flavor., in Handbook of Olfaction & Gustation: Modern Perspectives., R.L. Doty, Editor 2014. p. In press.

3.         Spence, C. and B. Piqueras-Fiszman, The Perfect Meal. The multisensory science of food and dining.2014, Chichester: John Wiley & Sons.

4.         Small, D.M., et al., The role of the human orbitofrontal cortex in taste and flavor processing. Ann. N.Y. Acad. Sci., 2007. 1121: p. 136-151.

Leaving a bad taste

Some emotion researchers suggest there are only a very small number of universal emotions: fear, anger, happiness, sadness, surprise, and disgust (see October, 2013: http://prescotttastematters.blogspot.com.au/2013/10/feeling-all-emotional.html). All other emotion terms, in this view, reflect these basic emotions. But even if you are inclined to believe that there are dozens, if not hundreds, of distinct emotional states, there remains one common indivisible emotion, disgust. Disgust sits alone in the cathedral of emotions, shunned even by dislike, guilty and worried. When talking about emotions elicited by foods, the uniqueness of disgust is rather …. unique, in that it is the only emotion that specifically implies a relationship to our sense of taste.

But, of course, foods are not supposed to disgust us, and fortunately most of us seldom come across examples of foods that do. Moreover, although our potential experience and expression disgust is innate, we need to learn what things should make us disgusted. It is a familiar enough scenario where a mother mimics the classic disgust face to a child about to eat something they have picked up from a footpath. With just a wrinkle of the nose, a baring of the upper teeth and a gaping mouth (and perhaps a “Yuk!”), the mother teaches the child a lesson about the potential dangers of otherwise edible items contaminated by …. who knows what, but certainly something that might cause disease. This common sense view is generally supported too by theoretical accounts of the evolutionary purpose of such a strong emotion which stress its role as disease-prevention mechanism [1].

Indeed, we could argue that disgust – despite the origins of the word – has little to do with taste or foods per se. Paul Rozin has characterized disgust as the emotional aspect of fear of contamination through, in the case of foods, consumption. Hence, food is just one of those things that we stick in out mouths that could potentially cause us harm via contamination. It is easy to show that food likes and dislikes show an inconsistent relationship to disgust. So, foods that are highly unpleasant, for example by being bitter, do not necessarily, or even often, induce feelings of disgust.  And, of course, it is possible for us to recognize that foods from other cultures could potentially taste great and be full of important nutrients, even if the idea of them caused a distinct shuddering of the spine.

We can see an illustration of this in the recent enthusiasm for insects as potential food sources in the future. A small, but growing, movement is examining how best to take advantage of the nutrients that insects can provide, and considering how best to deal with consumer responses to this [2]. Because of this interest, which is strong in Denmark, I was recently treated to a lunch provided by the Nordic Food Lab (www.nordicfoodlab.org), in which the menu contained a dish labeled “Peas and Bees”. The label was perfectly descriptive, and I managed to overcome my urge to say “thank you, I’m already full”. Those expecting little yellow and black highlights against the green background would have been disappointed, however, as only bee larvae were used.

Disgust doesn’t always require extreme foods or obvious contamination. Perfectly clean, everyday foods in perfectly clean bedpans will do it, as will being offered a glass of water into which a plastic model of a cockroach has been briefly dipped. In an earlier posting, I noted the extreme reactions to a choc-mint flavoured potato crisp (November, 2013: http://prescotttastematters.blogspot.com.au/2013/11/colour-me-minty.html). In many respects, this response to violation of expectations is a co-opting of so-called core disgust (that is, associated with ingestion of a potential contaminant) to cover a situation in which the unpredictability of the flavour could be a signal for possible danger.

A broadening of the disgust emotion to include those situations where contamination in the physical sense is not a risk is also evident. We talk, for example, about being disgusted by violence or by someone’s behavior or their appearance or their table manners. At least some of these reactions can be included under the term moral disgust. Rozin [3] suggests that the disgust emotion began life as an extension of our in-built responses to bitterness to which we added a cognitive appraisal of other (whether bitter or not) substances that we did not want to consume. This allows us to learn what to be disgusted by as a function of culture or violated expectations. Similarly, strong violations of beliefs, values or rules have become ‘attached’ to disgust. While we might just be using disgust as a metaphor in such situations, there is evidence that it is something more fundamental. Thus, in the same way that the classic disgust facial expression shares common features with facial expressions to unpalatably bitter foods, it can be shown that both core disgust and the moral disgust at being treated unfairly in a game activate a very similar set of facial muscles [4]. So, at least the expression of disgust appears to be highly similar.

A later study looked at associations between bitterness sensitivity, reflected in PROP taster status (May, 2013: http://prescotttastematters.blogspot.com.au/2013_05_01_archive.html), and different questionnaire scales of disgust sensitivity [5]. By distinguishing between different types of disgust: visceral (related to disease, bodily fluids and sexual activity) and moral, the study was able to show that those most sensitive to the bitterness of PROP (supertasters) were also significantly more sensitive to visceral disgust - that is, involving the possibility of contamination through ingestion or otherwise - but not moral disgust. It is possible therefore that the link between core disgust and moral disgust is merely semantic or metaphorical. An alternative explanation, however, is that (as suggested above) that across the two stages or jumps from bitterness responses to core disgust to moral disgust, the link between taste reactivity and moral disgust is weakened or lost.

In either case, examining the origins of moral disgust provides further opportunities to consider the possibility – raised in the previous two postings – that the source of many of our more complex emotional or personality traits can be found in quite fundamental early taste experiences.

                                                                                                                       

1.          Oaten, M.J., R.J. Stevenson, and T.I. Case, Disgust as a Disease-Avoidance Mechanism. PSYCHOL. BULL., 2009. 135(2): p. 303-321.

2.          Verbeke, W., Profiling consumers who are ready to adopt insects as a meat substitute in a Western society. Food Qual Pref, 2015. 39: p. 147-155.

3.          Rozin, P., From Oral to Moral. Science, 2009. 323: p. 1179-1180.

4.          Chapman, H.A., et al., In Bad Taste: Evidence for the Oral Origins of Moral Disgust. Science, 2009. 323: p. 1222-1226.

5.          Herz, R.S., PROP Taste Sensitivity is Related to Visceral but Not Moral Disgust. Chem. Percept., 2011. 4: p. 72-79.

Fear of frying

In my last post (July, 2014: A Taste of Emotion), I suggested the possibility that responses to tastes were linked to other emotional responses not merely by association to some third, common factor, but rather that variations in taste responsiveness might be the cause of different degrees of disinhibition (defined as inability to delay gratification) or how much we react to emotion-inducing stimuli of all kinds. Speculation is fine but how do we establish that one thing has caused another? Proving causal links between any two phenomena is always difficult, but we can ask what sort of evidence might make us take an idle speculation more seriously, even in the absence of absolute proof.

My own first question was whether we had any evidence that variation in taste preferences – apparently uniform at birth – emerges relatively early. If it does, then this can potentially be an influence on subsequent emotional development. This search sent me to the bowels of my dusty reprint archives (more strictly, the Endnote^tm program on my computer). The answer is that there is such evidence, at least when we consider sweetness preferences.

The strong preference for sweetness seen at birth starts to decline as the infant reaches the second half of their first year, such that some infants become relatively indifferent to sweetened water [1]. What does increase is variability in response to sweetness and a plausible hypothesis is that this is a consequence of differing exposures to a variety of foods, only some of which are sweet. And there is evidence for this. Infants fed sugar water prior to 6 months maintained a high preference for sweetness in water at 12 and 24 months. In effect, at 2 years of age, these infants were “sweet likers” (see: February, 2013: How sweet it is …. Or is it?). In contrast, those never fed sweet water did not show a strong desire to drink sweetened water over plain water [2]. Hence, one consequence of the practice of feeding infants sugar water is that is maintains the same high preference for sweetness that exists at birth into their second and third years.

Secondly, is there any evidence that taste experiences are linked to other emotions? Again, some of the “side effects’ of sweet tastes suggests that there might be. We know, for example, that sweet tastes can pacify an infant when they are receiving a painful hospital procedure [3]. The mechanism is not exactly certain but is likely to involve the activation of reward/pleasure pathways that inhibit pain. The reason that some mothers administer sugar water is presumably to help pacify their distressed infant. Through such pairings, the infant will learn to associate demands with reward – perhaps a precursor of later inability to inhibit immediate gratification.

But taste hedonics is not the only potential early influence on later emotions. One other obvious food-related candidate that may influence emotional development is food neophobia (FN). When seen in children, typically those aged 2 - 6 years, it is interpreted as an adaptive developmental stage that limits ingestion of unfamiliar, and therefore potentially dangerous, items that might be mistaken for food. It is thought to be mediated by the fear that unknown foods might taste unpleasant [4].

FN varies with a number of different factors (age and education, for example), and can be modified by experience with food variety. It also differs between cultures: in one study, consumers in New Zealand were shown to be on average more FN than a similar group from Japan. Dietary variety, or at least an attitude towards dietary variety, would seem to be the most logical reason for such differences. Nevertheless, FN is a strongly heritable trait [5] that persists into adulthood in substantial proportions of the population – up to 50% in some estimates. 

As in children, high FN adults have low dietary variety and show a reluctance to consider new foods – even if they are simply new versions of something already eaten.  They also dislike larger numbers of foods than their low FN neighbours. For the high FN individual, therefore, eating is associated with either boredom with the limited horizons of their diet or anxiety at the prospect of encountering something unfamiliar (or perhaps both) – in either case, food generates a relatively low level of pleasure compared to that experienced by the rest of us.

If basic tastes such as sweetness and bitterness elicit some of the very earliest post-partum emotions, then pleasure in our early years is clearly also heavily reliant on food. Rewards are often food based – the ice-cream or cake treat – and it is in these early years that children start to associate particular foods with other rewarding experiences, such as a trip to the well-known McDougalls Scottish burger ‘restaurant’ (Slogan: “It could be worse!”). Presumably for the highly FN child or adolescent, there is no such thing as being “pleasantly surprised” by food.

But there are many things about the FN experience that are unknown. How does the development of preferences for new foods develop in high FN individuals? Do high FN diets exclude whole categories of foods? One example might be very spicy or bitter foods, the consumption of which requires tolerance for initially unpleasant qualities (remember that FN is mediated by a fear that something with taste unpleasant). Rozin has suggested that the single most important question that can be asked of someone if you wish to know their food preferences is “what is your culture or ethnic group?”. It may be the follow-up question ought to involve measuring FN.

Strong evidence is lacking for an effect of FN beyond the food domain. However, more general personality traits such as sensation seeking are based on a broad enjoyment of novelty as well as “thrill seeking” in a variety of contexts. On another occasion, Rozin proposed that eating chilli might be a form of benign thrill seeking and so the question remains as to whether early failure to thrill seek with foods may predispose the individual to adopt similar approach when faced with novel experiences in general. 

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1. Schwartz, C., S. Issanchou, and S. Nicklaus, Developmental changes in the acceptance of the five basic tastes in the first year of life. Br J Nutr, 2009. 102(9): p. 1375-85.

2. Beauchamp, G.K. and M. Moran, Acceptance  of sweet and salty tastes in 2-year old children. Appetite, 1984. 5: p. 291-305.

3. Blass, E.M. and L.B. Hoffmeyer, Sucrose as an analgesic for newborn infants. Pediatrics, 1991. 87(2): p. 215-218.

4. Pliner, P., M. Pelchat, and M. Grabski, Reduction of neophobia in humans by exposure to novel foods. Appetite, 1993. 20: p. 111-123.

5. Knaapila, A., et al., Food neophobia shows heritable variation in humans. Physiol. Behav., 2007. 91: p. 573-578.

A taste of emotion

If you study perception, you tend not to be particularly concerned with the “secondary” emotions that sensory experiences might evoke (for a fuller discussion of this, see: http://www.expo.rai.it/eng/2014/07/08/taste-neuroscience-prescott/). Except if you study taste, in which case you can hardly avoid it. Emotional responses to tastes are, we can say with a reasonable degree of certainty, built into the fabric of the taste experience. Jacob Steiner’s famous photographs of newborns smiling or grimacing in response to sucrose and quinine [1], respectively, are if not exactly proof of this, then nevertheless compelling. The adaptive argument, too, is simple: tastes evoke emotions because this activates motivations to consume (calories, salt) or avoid (toxins) and hence promote survival. 

Our everyday language provides us with some hints that taste may find links with our emotions more broadly. Thus, unpleasant emotional experiences will leave a bitter taste in your mouth; we say that we can taste the fear, and of course sweetness is synonymous with all sorts of pleasant emotions.  The usual interpretation of such figures of speech is that we have co-opted tastes to help us describe emotions, perhaps because we tend to be poor at this.

But increasingly this does not seem to be the whole picture. A recently published study by Herbert and colleagues [2] examined the way in which autonomic nervous system responses - eye-blinks and changes in pupil diameter in response to startling bursts of white noise - are modified by emotion-inducing pictures. Importantly, though, they compared these responses in tasters and non-tasters of the bitter compound 6-n-propylthiouracil (PROP). This study was prompted by an earlier study in which PROP supertasters showed more intense self-reported emotional responses (anger, tension, sadness and fear; decreased mood and joy) than non-tasters or medium tasters after an anger-inducing film clip.

Herbert and colleagues found that startle responses were increased for pictures meant to elicit fear, anger, disgust, or pictures that were pleasant in content, relative to neutral pictures – but in the PROP-taster group only, and not the non-tasters. This suggests that the PROP tasters are hyper-responsive to both negative and positive emotions generally, not just to tastes.

Why would broad emotional responsiveness be linked to the ability to taste a particular bitter compound? Certainly, facial expressions to bitterness – the familiar grimace, nose-wrinkle and gape – has previously been thought to be the basis of the classic disgust facial response and perhaps even the origin of this basic emotion itself. Indeed, PROP super-tasters has been shown to be more responsive to the visceral – but not moral – aspects of disgust than are (medium) tasters and non-tasters, with taste sensitivity being positively correlated with degree of disgust [3].

But a common origin for disgust and bitterness dislike suggests something broader than the involvement of one particular bitter compound linked to a specific taste receptor (T2R38), one of perhaps 30 or more such bitter receptors. Two possibilities suggest themselves. The first is that responses to bitterness in general are reflective of an underlying overall emotional responsiveness, a relationship yet to be tested. In this sense, bitter substances are simply effective at eliciting emotions, in the same way as pictures of disgusting scenes or objects are effective. In addition, though, ratings of PROP intensity are often used as a proxy measure for taste responsiveness in general. PROP tasters also find sweet, salty sour and bitter tastes more intense than do PROP non-tasters (see for example, [4]).  This is more than likely due to the fact that increased numbers of taste buds underlie overall taste responsiveness, including (at least for those not ‘blind’ to it), PROP bitterness.

It has been hypothesized for some time that the pleasure given by sweetness is really no different than pleasure of any other sort, and that a common reward system in the brain underlies the popularity of sex, drugs and rock ‘n roll ….. and cake. But yet another broad link between taste and more general responsiveness to reward has been reported [5]. I have discussed the phenomenon of sweet liking and disliking previously (How sweet it is ... or is it?). The origins of this hedonic dimension are not well understood, but this study suggests that it may be linked to variations in overall disinhibition. Here, disinhibition was defined in terms of delay discounting – the idea of how much we value a given reward given now versus one that may be much larger, if we are willing to wait for it. So, if I say that I would rather have $10 now rather than $20 in a month, I am effectively discounting the later amount. In food terms, I can have one piece of chocolate now or three pieces in an hour. If you opt for the smaller reward now, you are unable to inhibit your need to satisfy your immediate desire. It turns out that such “discounters” are more likely to be sweet likers, that is, to prefer higher levels of sweetness. This then is another case of taste responses being seen in terms of more general responsiveness to reward.

An obvious interpretation is that, as mentioned above, pleasant tastes are merely part of an overall reward system that has adaptive value. However, there is an intriguing alternative explanation of why tastes might be so tied into other aspects of emotional life. If we start with the premise that tastes are responsible for some of the earliest emotions that we experience, it becomes possible to think about these early experiences having a large impact in shaping our broader emotional landscape. So, in this scenario, the fact you respond more positively to sweetness than I do becomes a major factor in whether or not you delay discount, not just for chocolates but in general for all reward. Similarly, sensitivity to bitterness – present at birth – has such a strong emotional impact that it influences the way you subsequently respond to all emotional stimuli. As a corollary, individual variations in taste sensitivity or hedonic value becomes a primary determinant of variations in our emotional responsiveness generally. 

Admittedly, this is a “chicken/egg” argument that may be impossible to determine but ….. the chronological primacy of taste hedonics does mean that we ought to consider the possibility that the taste of fear is not a way of helping us describe emotions but rather a clue to where our emotions originate.

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1. Steiner, J.E., et al., Comparative expression of hedonic impact: affective reactions to taste by human infants and other primates. . Neurosci. Biobehav. Rev., 2001. 25(1): p. 53-74.

2. Herbert, C., et al., Supertaster, super reactive: Oral sensitivity for bitter taste modulates emotional approach and avoidance behavior in the affective startle paradigm. Physiol Behav, 2014. 135C: p. 198-207.

3. Herz, R.S., PROP Taste Sensitivity is Related to Visceral but Not Moral Disgust. Chem. Percept., 2011. 4: p. 72-79.

4. Prescott, J., N. Ripandelli, and I. Wakeling, Intensity of tastes in binary mixtures in PROP non-tasters, medium-tasters and super-tasters. . Chem. Senses, 2001. 26: p. 993-1003.

5.    Weafer, J., A. Burkhardt, and H. de Wit, Sweet taste liking is associated with impulsive behaviors in humans. Front Behav Neurosci, 2014. 8: p. 228.

The subtext on context

“What’s the weirdest food you have encountered?”. I suppose that’s a reasonable question if you write about food preferences – we all are fascinated by the unusual. And it is why I opened Taste Matters [1] with a description of hakarl, the (to me) repulsive Icelandic dish made from rotten shark meat. My more general answer, though, is usually disappointing: any food – including what you ate for lunch today – can be weird, depending on whom you ask. If rotten shark meat is a delicacy, who’s to say that roast chicken, or oysters, or flat bread topped with tomato, cheese, and tiny fish won’t seem like odd things to eat.

It is all about context. As food consumers, our focus is naturally on the foods that we eat. Are they tasty, healthy, interesting and so on? But if you shift focus from the food to consumers themselves, it becomes apparent that all responses to foods – likes, dislikes, strangeness - are relative …. to something. Even the question of whether a taste is strong or weak is only partly based in the food itself. Is your coffee very sweet? That’s merely a function of how much sugar you normally add to it – in other words, your memory of how sweet coffee should be. Is the dish too spicy? Probably not, if it is similar to what you normally eat. Your accumulated memories of what you have eaten, and in particular most recently eaten, provide an internal context against which a food or flavour can be said to be weak or strong, and hence pleasant or unpleasant.

Similarly, our past experiences with foods and the combinations of tastes, aromas, textures and colours that typically occur lead to expectations prior to eating. Violating these expectations can lead to a variety of outcomes, depending on the context. At a purely perceptual level, it is easy to demonstrate that a lime-flavoured drink will be identified most often as berry-flavoured if it is coloured red. On the other hand, a colourless drink will be judged as less intense in flavour. We tend to trust our eyes more than our ability to identify flavours. Such demonstrations can be a source of embarrassment when this is done with wine enthusiasts, who will talk at length about the cherry, blackberry and tobacco notes of a white wine to which red food colouring has been added. 

Confounding expectations is not always a bad thing. A favourite traveller’s tale concerns the tiny restaurant found in a back alley of a small town off the beaten track in an exotic location. The seating was fruit crates, the waiter spoke only the local language, and the kitchen wasn’t large enough for two people. The food, however, was sensational and produced an enduring memory of a great meal experience. Of course, we can have great meal experiences at Michelin-starred restaurants in major cities, but it is the surprise element – the wonderful flavours despite the context – that provide both the additional pleasure, and a way of locking it into our memory. Moreover, our surprise meal transported to a different context – say, a plush restaurant with formal service – is far less likely to be memorable precisely because our expectations for fine food were met exactly. Consumer scientist Herb Meiselman showed some years ago that the pleasantness of the same meal would be judged quite differently served in different contexts such as a restaurant, a canteen or in a hospital setting [2].

Part of the enjoyment of our exotic-location meal derives, of course, from the idea of authenticity. The food takes on an added pleasure if we feel that we are experiencing what the locals experience. This is such a common pursuit these days that authenticity – real or perceived - becomes a selling point and sometimes also a way of subtly pushing us towards particular food choices. What’s more appealing: long noodles with meat sauce or tagliatelle a la Bolognese? One is just a meal but the other is an ethnic meal (unless you are from Bologna, of course). And what would you rather drink with it? Even if you can afford to order a nice Burgundy, doesn’t the idea of the unknown local red wine – the owner’s selection – draw your interest just that much more? A great wine versus a wine experience.

The influence of a context doesn’t have to be subtle. Most people can convince themselves about the added appeal of a meal in a restaurant in which a few cultural stereotypes are on display over the same meal cooked at home or in a generic restaurant environment. Rude waiter – check. Brass fittings – check. Edith Piaf soundtrack – check. Yes, this is not a steak, chips and wilted lettuce leaf, it’s a genuine steak frites. Sophisticated and worldly diners might expect themselves to be immune from such obvious influences: their focus is on the food, the technique, the playful presentation. But the cues to context that set up expectations are not necessarily open to conscious inspection. One study, for example, examined the impact of playing French or German style background music on alternate days in the wine section of a supermarket [3]. Despite the fact that when questioned, consumers were unaware of the type of music being played, German and French wines were more often purchased on days when German and French music, respectively, was played. The researchers’ quite plausible explanation is that the music activated other, unconscious, nationality-based associations that nudged the consumers towards the purchase of a wine that was congruent – that is, a good fit – with those associations.

This idea helps explain too how wonderful food or wine in one context totally fails to impress when removed to a different context. Sitting in the sun, watching the ocean, a piece of grilled fish on the plate and a glass of local wine in hand seems a perfect combination. Remove the sun, ocean and carefree thoughts, however, and the same wine seems like a very odd purchase to have brought home from holidays. These important contextual cues are now being explicitly utilized by some chefs who have recognized that eating is a multisensory experience, the pleasure of which is enhanced by an environment that stimulates our senses and activates memories of past experiences. A well-known example of this is apparent in a dish entitled “The Sounds of the Sea”, created by British chef Heston Blumenthal [4]. The diner listens to the sound of waves on the shore (via an iPod hidden in a conch shell) to accentuate the visual presentation of seafood on a tapioca-based ‘sandy beach’, with a vegetable and seafood based foam as the rolling waves. The result is a multisensory immersion in sights, sounds, odours, textures and tastes with contributions from memories and emotions that evoke warm feelings of nostalgia for days on the seashore. 

An ethnic theme in a restaurant may influence our food selection and enjoyment, but our actual culture is really the key context through which food preferences are formed and foods are interpreted. Around 30 years ago, food psychologist Paul Rozin and his wife, food writer Elizabeth Rozin, formulated the idea of culturally-based flavour principles by asking two important questions [5]. The first of these was whether each culture’s cuisine could be defined in a list of key ingredients and cooking styles that distinguished it from all other cuisines. Essentially, what they wanted to know was what made Italian food Italian or Greek food Greek and, for example, if we ate a chicken dish each from Italy, Spain and Greece, what would be the essential features that would allow us to know their origins.  After all, each of these cuisines uses olive oil, garlic and tomato in their cooking, so they are in many ways similar. But we can still see differences between them in the use of different herbs and spices such as oregano, basil, rosemary, chilli, paprika, saffron, thyme, parsley, fennel and so on. Even when there is overlap in the types of spices used, there will be different combinations and emphases in the cultures for different dishes. Of course, when cultures are geographically more remote, or the history of influences is dramatically different, the differences in flavour principles become more obvious. 

Secondly, the Rozins asked whether flavour principles might have some purpose, other than being merely a matter of convenience is using whatever ingredients were locally available. They proposed that flavour principles actually performed a vital, biologically important function (apart from making chicken more interesting to eat). They recognized that all of us tend to be rather wary of incorporating new foods into our diet – the scientific term is food neophobia – an evolutionary hangover from our time in the wild where new plants could as often be poisonous as nutritious. But given that even in more modern times, the environment is not always friendly to food sources, and it pays to be flexible and be able to incorporate new sources of proteins and plant foods in the diet. Cooking in a familiar way, with familiar ingredients, converts a potential source of neophobia into a recognizable dish that is more likely to be accepted than rejected as unfamiliar.

The members of each culture learn that the flavour is the acceptable context for the various ingredients that provide sources of protein – whether it be chicken, fish, insects, rotten shark, tripe – and other nutrients. And this learning takes place even before we are born. Research over the past two decades has shown that flavours are passed from a mother’s diet into the amniotic fluid surrounding a foetus. Importantly, this provides exposure to, and hence familiarity with, these flavours that can be seen in the preferences of the baby at the time of weaning. Foetal exposure to the flavour of a vegetable such as carrot will mean that carrot flavour is more readily accepted even when the infant is 2 years old. Of course, what the mother is doing is inadvertently passing of culturally-based food knowledge: the flavour principles of the mother’s diet become those of the infant. The culture of food thus is transmitted from generation to generation - but how such transmission will survive globalization of foods is unclear.

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1. Prescott, J., Taste Matters. Why we like the foods we do. 2012, London: Reaktion Books.
2. Edwards, J.S., et al., The influence of eating location on the acceptability of identically prepared foods. Food Qual Pref, 2003. 14: p. 647-652.
3. North, A.C., D.J. Hargreaves, and J. McKendrick, The influence of in-store music on wine selections. J Appl Psychol., 1999. 84(2): p. 271-276.
4. Blumenthal, H., The Big Fat Duck Cookbook 2008, London: Bloomsbury.
5. Rozin, E. and P. Rozin, Culinary themes and variations. Nat. Hist., 1981. 90(2): p. 6-14.