Multisensory Flavor Perception Research Articles

Flavor-food ingredient interactions in fortified or reformulated novel food: Binding behaviors, manipulation strategies, sensory impacts, and future trends in delicious and healthy food design.

With consumers gaining prominent awareness of health and well-being, a diverse range of fortified or reformulated novel food is developed to achieve personalized or tailored nutrition using protein, carbohydrates, or fat as building blocks. Flavor property is a critical factor in the acceptability and marketability of fortified or reformulated food. Major food ingredients are able to interact with flavor compounds, leading to a significant change in flavor release from the food matrix and, ultimately, altering flavor perception. Although many efforts have been made to elucidate how food matrix components change flavor binding capacities, the influences on flavor perception and their implications for the innovation of fortified or reformulated novel food have not been systematically summarized up to now. Thus, this review provides detailed knowledge about the binding behaviors of flavors to major food ingredients, as well as their influences on flavor retention, release, and perception. Practical approaches for manipulating these interactions and the resulting flavor quality are also reviewed, from the scope of their intrinsic and extrinsic influencing factors with technologies available, which is helpful for future food innovation. Evaluation of food-ingredient interactions using real food matrices while considering multisensory flavor perception is also prospected, to well motivate food industries to investigate new strategies for tasteful and healthy food design in response to consumers' unwillingness to compromise on flavor for health.

‘Tasting Imagination’: What Role Chemosensory Mental Imagery in Multisensory Flavour Perception?

A number of perplexing phenomena in the area of olfactory/flavour perception may fruitfully be explained by the suggestion that chemosensory mental imagery can be triggered automatically by perceptual inputs. In particular, the disconnect between the seemingly limited ability of participants in chemosensory psychophysics studies to distinguish more than two or three odorants in mixtures and the rich and detailed flavour descriptions that are sometimes reported by wine experts; the absence of awareness of chemosensory loss in many elderly individuals; and the insensitivity of the odour-induced taste enhancement (OITE) effect to the mode of presentation of olfactory stimuli (i.e., orthonasal or retronasal). The suggestion made here is that the theory of predictive coding, developed first in the visual modality, be extended to chemosensation. This may provide a fruitful way of thinking about the interaction between mental imagery and perception in the experience of aromas and flavours. Accepting such a suggestion also raises some important questions concerning the ecological validity/meaning of much of the chemosensory psychophysics literature that has been published to date.

Exploring the Links between Colours and Tastes/Flavours

The colour and other visual appearance properties of food and drink constitute a key factor determining consumer acceptance and choice behaviour. Not only do consumers associate specific colours with particular tastes and flavours, but adding or changing the colour of food and drink can also dramatically affect taste/flavour perception. Surprisingly, even the colour of cups, cutlery, plates, packages, and the colour of the environment itself, have also been shown to influence multisensory flavour perception. The taste/flavour associations that we hold with colour are context-dependent, and are often based on statistical learning (though emotional mediation may also play a role). However, to date, neither the computational principles constraining these ubiquitous crossmodal effects nor the neural mechanisms underpinning the various crossmodal associations (or correspondences) that have been documented between colours and tastes/flavours have yet been established. It is currently unclear to what extent such colour-taste/flavour correspondences ought to be explained in terms of semantic congruency (i.e., statistical learning), and/or emotional mediation. Bayesian causal inference has become an increasingly important tool in helping researchers to understand (and predict) the multisensory interactions between the spatial senses of vision, audition, and touch. However, a network modelling approach may be of value moving forward. As made clear by this review, there are substantial challenges, both theoretical and practical, that will need to be overcome by those wanting to apply computational approaches both to understanding the integration of the chemical senses in the case of multisensory flavour perception, and to understanding the influence of colour thereon.

What Is the Relationship between the Presence of Volatile Organic Compounds in Food and Drink Products and Multisensory Flavour Perception?

This narrative review examines the complex relationship that exists between the presence of specific configurations of volatile organic compounds (VOCs) in food and drink products and multisensory flavour perception. Advances in gas chromatography technology and mass spectrometry data analysis mean that it is easier than ever before to identify the unique chemical profile of a particular food or beverage item. Importantly, however, there is simply no one-to-one mapping between the presence of specific VOCs and the flavours that are perceived by the consumer. While the profile of VOCs in a particular product undoubtedly does tightly constrain the space of possible flavour experiences that a taster is likely to have, the gustatory and trigeminal components (i.e., sapid elements) in foods and beverages can also play a significant role in determining the actual flavour experience. Genetic differences add further variation to the range of multisensory flavour experiences that may be elicited by a given configuration of VOCs, while an individual’s prior tasting history has been shown to determine congruency relations (between olfaction and gustation) that, in turn, modulate the degree of oral referral, and ultimately flavour pleasantness, in the case of familiar foods and beverages.

Adaptive weighting of taste and odor cues during flavor choice.

Colloquially referred to as "taste," flavor is in reality a thoroughly multisensory experience. Yet, a mechanistic understanding of the multisensory computations underlying flavor perception and food choice is lacking. Here, we used a multisensory flavor choice task in rats to test specific predictions of the statistically optimal integration framework, which has previously yielded much insight into cue integration in other multisensory systems. Our results confirm three key predictions of this framework in the unique context of flavor choice behavior, providing novel mechanistic insight into multisensory flavor processing.NEW & NOTEWORTHY The authors demonstrate that rats make choices about which flavor solution (i.e., taste-odor mixture) to consume by weighting the individual taste and odor components according to the reliability of the information they provide about which solution is the preferred one. A similar weighting operation underlies multisensory cue combination in other domains and offers novel insight into the computations underlying multisensory flavor perception and food choice behavior.

Multisensory Flavour Perception: Blending, Mixing, Fusion, and Pairing Within and Between the Senses.

This review summarizes the various outcomes that may occur when two or more elements are paired in the context of flavour perception. In the first part, I review the literature concerning what happens when flavours, ingredients, and/or culinary techniques are deliberately combined in a dish, drink, or food product. Sometimes the result is fusion but, if one is not careful, the result can equally well be confusion instead. In fact, blending, mixing, fusion, and flavour pairing all provide relevant examples of how the elements in a carefully-crafted multi-element tasting experience may be combined. While the aim is sometimes to obscure the relative contributions of the various elements to the mix (as in the case of blending), at other times, consumers/tasters are explicitly encouraged to contemplate/perceive the nature of the relationship between the contributing elements instead (e.g., as in the case of flavour pairing). There has been a noticeable surge in both popular and commercial interest in fusion foods and flavour pairing in recent years, and various of the ‘rules’ that have been put forward to help explain the successful combination of the elements in such food and/or beverage experiences are discussed. In the second part of the review, I examine the pairing of flavour stimuli with music/soundscapes, in the emerging field of ‘sonic seasoning’. I suggest that the various perceptual pairing principles/outcomes identified when flavours are paired deliberately can also be meaningfully extended to provide a coherent framework when it comes to categorizing the ways in which what we hear can influence our flavour experiences, both in terms of the sensory-discriminative and hedonic response.

The visual appearance of beer: A review concerning visually-determined expectations and their consequences for perception.

This review critically evaluates the literature concerning the impact of visual appearance cues (including colour, foam, and cloudiness) on people's perception in the beer category. The authors assess both the sensory expectations that are elicited by the visual appearance of beer, and the extent to which those expectations carry-over to influence the actual tasting experience. Beer is a particularly intriguing category to study since the differing production rules in different countries mean that there is not always the same scope to modify the colour in order to meet perceived consumer demands. What is more, there is currently disagreement in the literature concerning the impact of beer colour and foam on people's expectations of beer prior to tasting, and their multisensory flavour perception on tasting. Given how much beer is consumed annually, it is surprising that more research has not been published that assesses the undoubtedly important role of visual appearance in this beverage category. Part of the reason for this may simply be that it is difficult to create consistent experimental stimuli given the rapid transition of the head of the beer post-serving.

Background soundscapes influence the perception of ice-cream as indexed by electrophysiological measures.

Listening to specific soundscapes can influence multisensory flavour perception. In the present study, changes in people's perception of the flavour of ice-cream were tracked over time as they listened to a café soundscape, and when this soundscape was overlaid with either bird, machine, or forest soundscapes. In addition, emotions and electrophysiological measures were recorded in order to help understand any changes in taste/flavour perception. The results of Temporal Dominance of Sensation (TDS) analysis revealed that cocoa was dominant early in the consumption episode while listening to the control café soundscape. Sweetness and creaminess were dominant at the start of the consumption episode while listening to the café-forest soundscape. Creaminess was dominant at the start of the consumption episode while listening to the café-bird soundscape. Bitterness was perceived at the end of the consumption period while listening to the café control and café-machine soundscapes. These findings demonstrate the crossmodal influence of audition on perception in the chemical senses. As expected, negative emotions were significantly higher when listening to the machine soundscape, while positive emotions were significantly higher when listening to café-forest and café-bird soundscapes. Evaluating ice-cream while listening to the café-machine soundscape evoked negative emotions associated with bitterness and creaminess, that were also associated with increased heart rate (HR) and respiration rate (RESP). When listening to the café-forest soundscape, ice-cream was associated with sweetness, and positive emotions (e.g., love, satisfaction, happiness, amusement and enjoyment). This might have led to increased blood volume pulse (BVP) amplitude, which is itself indicative of a relaxed state. Enhancing eating experiences by means of atmospheric soundscapes that are designed specifically to accentuate specific aspects of multisensory taste/flavour perception is currently an area of interest in the food sciences literature and will likely lead to future commercial applications.

The Role of Intrinsic and Extrinsic Sensory Factors in Sweetness Perception of Food and Beverages: A Review.

When it comes to eating and drinking, multiple factors from diverse sensory modalities have been shown to influence multisensory flavour perception and liking. These factors have heretofore been strictly divided into either those that are intrinsic to the food itself (e.g., food colour, aroma, texture), or those that are extrinsic to it (e.g., related to the packaging, receptacle or external environment). Given the obvious public health need for sugar reduction, the present review aims to compare the relative influences of product-intrinsic and product-extrinsic factors on the perception of sweetness. Evidence of intrinsic and extrinsic sensory influences on sweetness are reviewed. Thereafter, we take a cognitive neuroscience perspective and evaluate how differences may occur in the way that food-intrinsic and extrinsic information become integrated with sweetness perception. Based on recent neuroscientific evidence, we propose a new framework of multisensory flavour integration focusing not on the food-intrinsic/extrinsic divide, but rather on whether the sensory information is perceived to originate from within or outside the body. This framework leads to a discussion on the combinability of intrinsic and extrinsic influences, where we refer to some existing examples and address potential theoretical limitations. To conclude, we provide recommendations to those in the food industry and propose directions for future research relating to the need for long-term studies and understanding of individual differences.

Changes in flavour, emotion, and electrophysiological measurements when consuming chocolate ice cream in different eating environments

The eating context influences eating behaviour as well as the hedonic response to food. This study investigated temporal changes in the perceived flavour of chocolate ice cream when consumed in a laboratory, café, university study area, and a city bus stop, and further examined how emotion and electrophysiological measures were influenced by these environments. In this study, three measures were obtained from 160 participants. First, temporal changes in multisensory flavour perception after consuming chocolate ice cream in different environments were determined using the Temporal Dominance of Sensations (TDS) method. Second, participants’ emotional responses were measured after consuming ice cream using a check-all-that-apply (CATA) list of emotions. Finally, standard electrophysiological measures of heart rate (HR), blood volume pulse (BVP), and skin conductance (SC) were also obtained. When ice cream was consumed in the café, it was associated with positive emotions and a sweet taste/flavour. When consumed in the university study area, it was correlated with both positive and negative emotions, and cocoa and milky flavours. Consumption at the city bus stop was correlated with the most negative emotions, and with roasted and bitter tastes/flavours. The laboratory environment was only correlated with the attributes of ‘concentrating’ and creamy flavour. SC was significantly increased in the university study area as compared to the laboratory, and HR was significantly decreased in the university study area environment as compared to the bus stop. The evidence from this study therefore indicates that the eating context constitutes an important factor to consider when carrying out sensory testing as participants’ emotions, perceptions, and electrophysiological responses are influenced differently dependent upon the eating context.

On the Relationship(s) Between Color and Taste/Flavor.

. Experimental psychologists, psychophysicists, food/sensory scientists, and marketers have long been interested in, and/or speculated about, what exactly the relationship, if any, might be between color and taste/flavor. While several influential early commentators argued against there being any relationship, a large body of empirical evidence published over the last 80 years or so clearly demonstrates that the hue and saturation, or intensity, of color in food and/or drink often influences multisensory flavor perception. Interestingly, the majority of this research has focused on vision’s influence on the tasting experience rather than looking for any effects in the opposite direction. Recently, however, a separate body of research linking color and taste has emerged from the burgeoning literature on the crossmodal correspondences. Such correspondences, or associations, between attributes or dimensions of experience, are thought to be robustly bidirectional. When talking about the relationship between color and taste/flavor, some commentators would appear to assume that these two distinct literatures describe the same underlying empirical phenomenon. That said, a couple of important differences (in terms of the bidirectionality of the effects and their relative vs. absolute nature) are highlighted, meaning that the findings from one domain may not necessarily always be transferable to the other, as is often seemingly assumed.

“Jastrow's Bistable Bite”: What happens when visual Bistable illusion meets the culinary arts?

We report on the creative process underlying the development of an edible version of Jastrow's (1899) famous bistable duck/rabbit illusion. The culinary research team at Kitchen Theory took this well-known visual illusion as the inspiration for the creation of a new dish using both duck and rabbit as key ingredients. A simplified version of the illusion was stencilled onto the plate and a ‘crispy dumpling’ of confit duck and rabbit leg placed to one side. We report the results of a large-scale online study designed to assess the visual percept elicited on first viewing the edible version of “Jastrow's Bistable Bite” dish. We assessed whether the orientation in which the dish is presented initially would influence the percept that dominates initially. The results revealed that when served in certain specific orientations the two interpretations – duck and rabbit – were roughly equally dominant. Hence, serving the dish to the diner in one of these specific orientations is likely ideal for generating discussion at the dinner table around the role of vision in multisensory flavour perception. The hope is that the introduction of this dish onto the menu can be used to promote a sustainability message (given that many people believe that we should be eating more rabbit than is currently the case).

Multisensory flavor perception: The relationship between congruency, pleasantness, and odor referral to the mouth

Our hedonic response to a food is determined by its flavor, an inherently multisensory experience that extends beyond the mere addition of its odor and taste. While congruency is known to be important for multisensory processes in general, little is known about its specific role in flavor processing. The aim of the present study was to delineate the effects of odor-taste congruency on two central aspects of flavor: odor referral (or mislocalization) to the mouth, and pleasantness. We further aimed to test whether an eventual effect on pleasantness was mediated by odor referral. Aqueous solutions containing odors and tastes were prepared to create food-like stimuli with varying degrees of congruency, ranging from maximally incongruent to maximally congruent in nine steps. Thirty participants reported where they perceived the odors, and how much they liked the solutions. Congruency had a positive linear effect both on odor referral to the oral cavity and on pleasantness. However, the effect of congruency on pleasantness was not mediated by odor referral. These results indicate that as an odor-taste mixture approximates a mental representation of a familiar food, its components are increasingly merged into one perceptual object sensed in the mouth. In parallel, the mixture is evaluated as increasingly pleasant, which promotes consumption of familiar foods that have been determined through experience to be non-toxic. While the modulatory role of congruency on pleasantness and odor referral was confirmed, our results also indicate that these effects arise through distinct perceptual mechanisms.

Assessing the impact of the tableware and other contextual variables on multisensory flavour perception

Currently little is known about how the non-edible items associated with eating and drinking (tableware items such as the plates, bowls, cutlery, glasses, bottles, condiment containers, etc.), or even environmental factors (such as the lighting and/or background music), affect people’s perception of foodstuffs. Here, we review the latest evidence demonstrating the importance of these contextual variables on the consumer’s behavioural and hedonic response to, and sensory perception of, a variety of food and drink items. These effects are explained by a combination of psychological factors (high level attributes, such as perceived quality, that may be mediating the effects under consideration), perceptual factors (such as the Ebbinghaus-Titchener size-contrast illusion and colour contrast in the case of the colour of the plateware affecting taste/flavour perception), and physiological-chemical factors (such as differences in the release of volatile organic compounds from differently-shaped wine glasses). Together, these factors help to explain the growing body of evidence demonstrating that both the tableware and the environment can have a profound effect on our perception of food and drink.

MOUTH‐WATERING: THE INFLUENCE OF ENVIRONMENTAL AND COGNITIVE FACTORS ON SALIVATION AND GUSTATORY/FLAVOR PERCEPTION

ABSTRACTIn this article, the evidence demonstrating the significant role that saliva plays in taste and flavor perception in humans is reviewed. Empirical research highlighting the effects of a number of food‐related, environmental and higher‐order cognitive factors (such as attention, mental imagery and labeling) on salivary flow is critically examined. The argument is put forward that changes in salivary flow may have contributed to the results of a number of recent studies of multisensory flavor perception. Indeed, it is striking how rarely salivation is mentioned by cognitive psychologists and cognitive neuroscientists when studying gustatory and/or multisensory flavor perception. The hope is that this review may help to redress this potentially important imbalance. Recommendations for future research in this area are included, and finally, the potential commercial applications of these findings are also reviewed briefly.PRACTICAL APPLICATIONSThis review highlights the potential problems of interpretation that academic researchers interested either directly in the topic of taste or multisensory flavor perception, or indirectly in the effects of environmental (e.g., atmospheric) changes on flavor perception can run into if they fail to consider the role that any overt changes in salivation may have on the effects they report.This review also highlights the fact that in commercial settings, the large baseline individual differences in salivation are likely to swamp anything that the chef/company can do to modify the salivary flow of their customers via environmental/labeling interventions.

Multisensory flavor perception: Assessing the influence of fruit acids and color cues on the perception of fruit-flavored beverages

We report a study designed to investigate the influence of fruit acids (in particular, citric and malic acid) on people’s perception of the identity and the intensity of a variety of different fruit-flavored solutions. Participants had to identify the flavor of fruit-flavored drinks that were colored yellow, grey, orange, red, or else were presented as colorless solutions. The participants also rated the intensity of flavor, sweetness, and sourness of each solution using a Labelled Magnitude Scale (LMS). The participants identified the flavors of the beverages more accurately when citric and malic acids were added to the solutions, and/or when the solutions were colored appropriately. Moreover, the perception of flavor intensity was modulated by the presence of the fruit acids in the solutions.

The multisensory perception of flavor: Assessing the influence of color cues on flavor discrimination responses

Two experiments are reported that were designed to investigate the influence of visual color cues on people’s flavor discrimination and flavor intensity ratings for a variety of fruit-flavored solutions. In Experiment 1, the participants had to associate specific flavors with solutions of various colors simply by looking at them (i.e., without tasting them). In Experiment 2, the participants tasted the solutions and had to discriminate the flavor of solutions that had been colored either ‘appropriately’ or ‘inappropriately’, or else presented as colorless solutions. The participants were explicitly informed that the colors of the solutions provided no useful information regarding the actual flavor identity of the solutions. The participants also rated the flavor intensity of the solutions. The accuracy of participants’ flavor discrimination performance was significantly lower when the solutions were colored inappropriately than when they were colored appropriately (or else were presented as colorless solutions). These results show that the modulatory effect of visual cues on flavor perception can override participants’ awareness that the solutions would frequently be colored inappropriately.