Recent developments in identifying and quantifying emotions during food consumption

Neuroscience tools to study the effect of the presentation form on food-evoked emotion for senior population

The elderly population holds significance among consumers because many of them experience alterations in taste and smell or suffer from physical disorders. These factors can lead to reduced food intake, malnutrition, and, consequently, serious health problems. Therefore, there is a need to develop tailored products for seniors, offering both nutrition and appealing foods with easily consumable textures. Among the various characteristics of food, appearance stands out as one of the most critical aspects influencing food preferences and choices. Surprisingly, there is limited knowledge about how food shape affects the holistic emotional responses of seniors. The objective of this study was to investigate the impact of food shape on the emotional responses of seniors. This exploration involved the use of explicit methods, such as self-reported questionnaires, and implicit methods, including the measurement of skin conductance responses and facial expressions, as well as their combination. To achieve this goal, we enlisted the participation of 50 individuals (54 % women) from the senior population aged between 55 and 75 years. These participants evaluated two food products with identical sensory characteristics in terms of taste, texture, and flavor. However, these products differed in terms of their shape. We measured their degree of liking and emotional responses using a 7-point hedonic scale, EsSense25, in conjunction with galvanic skin response, and facial expressions, which served as representatives of behavioural and physiological responses. The multivariate analysis allowed to examine sample configurations by gender and establish associations between variables. The combination of implicit and explicit methods led to better discrimination of samples of the same category than the use of each of the methods independently. Although both samples elicited equivalent liking perceptions, they evoked distinct emotional responses, measured at cognitive, physiological, and behavioural levels. In general, men and women experienced different emotions while observing, smelling, handling, or consuming both samples, both consciously and unconsciously. This newfound knowledge could be valuable when designing food products for this demographic. The ultimate goal is to engage consumers and enhance their enjoyment of the food experience by offering more visually appealing food options.

The Effect of Response Conditions on Food Images-Evoked Emotions Measured Using the Valence × Arousal Circumplex-Inspired Emotion Questionnaire (CEQ)

In 2020, a single-response-based, valence × arousal circumplex-inspired emotion questionnaire (CEQ) was developed. Using a between-participants design, previous studies have found that a multiple response (MR) condition better discriminated test samples (e.g., written food names) based on their evoked emotions than a single response (SR) condition. This research, comprising Studies 1 and 2, aimed to determine the effect of response conditions (i.e., SR vs. MR) on emotional responses to food image samples, using a within-participants design. In Study 1, 105 Korean participants were asked to select a pair of emotion terms (i.e., SR condition) or select all pairs representing their evoked emotions (i.e., MR condition) from a list of 12 pairs of emotion terms of the CEQ, in response to the 14 food images. Both SR and MR conditions were tested within a remote (online) session. To minimize both a potential carry-over effect of the "within-participants design" and an influence of environmental factors in the remote testing, Study 2 asked 64 U.S. participants to do so over two separated sessions on two different days in a controlled laboratory setting. In both Studies 1 and 2, participants selected the CEQ's emotion-term pairs in the MR condition more frequently than in the SR condition, leading to the MR condition's higher capacity to discriminate test samples. While the configurations of the correspondence analysis biplots drawn in the SR and MR conditions were similar, those in the MR condition were more likely to be similar to the configurations of the principal component analysis biplots drawn from the ratings of valence and arousal for food image samples. In conclusion, this study provides robust empirical evidence that the MR condition can perform better in capturing sample differences in food-evoked emotions, while the SR condition is also effective in characterizing emotional profiles of test samples. Our findings will provide practical insights to sensory professionals, enabling them to effectively leverage the CEQ or its variants when measuring food-evoked emotions.

Analysis of facial emotion expression in eating occasions using deep learning

Eating is experienced as an emotional social activity in any culture. There are factors that influence the emotions felt during food consumption. The emotion felt while eating has a significant impact on our lives and affects different health conditions such as obesity. In addition, investigating the emotion during food consumption is considered a multidisciplinary problem ranging from neuroscience to anatomy. In this study, we focus on evaluating the emotional experience of different participants during eating activities and aim to analyze them automatically using deep learning models. We propose a facial expression-based prediction model to eliminate user bias in questionnaire-based assessment systems and to minimize false entries to the system. We measured the neural, behavioral, and physical manifestations of emotions with a mobile app and recognize emotional experiences from facial expressions. In this research, we used three different situations to test whether there could be any factor other than the food that could affect a person's mood. We asked users to watch videos, listen to music or do nothing while eating. This way we found out that not only food but also external factors play a role in emotional change. We employed three Convolutional Neural Network (CNN) architectures, fine-tuned VGG16, and Deepface to recognize emotional responses during eating. The experimental results demonstrated that the fine-tuned VGG16 provides remarkable results with an overall accuracy of 77.68% for recognizing the four emotions. This system is an alternative to today's survey-based restaurant and food evaluation systems.

Emotional responses to taste and smell stimuli: Self-reports, physiological measures, and a potential role for individual and genetic factors

Taste and olfaction elicit conscious feelings by direct connection with the neural circuits of emotions that affects physiological responses in the body (e.g., heart rate and skin conductance). While sensory attributes are strong determinants of food liking, other factors such as emotional reactions to foods may be better predictors of consumer choices even for products that are equally-liked. Thus, important insights can be gained for understanding the full spectrum of emotional reactions to foods that inform the activities of product developers and marketers, eating psychologist and nutritionists, and policy makers. Today, self-reported questionnaires and physiological measures are the most common tools applied to study variations in emotional perception. The present review discusses these methodological approaches, underlining their different strengths and weaknesses. We also discuss a small, emerging literature suggesting that individual differences and genetic variations in taste and smell perception, like the genetic ability to perceive the bitter compound PROP, may also play a role in emotional reactions to aromas and foods.

Studying the Emotional Response to Insects Food Products

Insects have been proposed as a sustainable food solution due to their environmental, nutritional, and socioeconomic value; however, in the western world, insects are viewed as disgusting. This research aimed to understand the acceptance of insect-based products in the US market by studying the emotional response to such. A survey of 826 consumers was conducted using (1) a modified version of the EsSense Profile^® questionnaire to capture the emotional response to pictures of different kinds of foods, (2) images to evaluate the influence of the presence or absence of non-visible insects in food products, (3) information about the environmental value of insects, and (4) socioeconomic demographics. Disgust was found as a barrier to product acceptance. Insect food products were positively correlated with the emotions of interest, understanding, daring, adventurous, and worried, and negatively correlated with the emotions satisfied, good, pleasant, happy, calm, warm, nostalgic, and secure. The influence of sustainability-related information on the emotional response to such products is complex and should be carefully considered.

The Asymmetric Emotional Associations to Beverages: An Approach through the Theory of Positive Asymmetry

Consumers experience mainly positive emotions in response to food products, and the reason is that, for most individuals, eating and drinking is a pleasurable experience. On this premise, in light of the Theory of Positive Asymmetry, this study answers the following question: “What emotions prevail in beverage consumption?” A MANOVA test was developed comparing emotions associated with spirits (n = 247), alcoholic beverages (n = 560) and non-alcoholic beverages (n = 254). The findings report that the positive asymmetry of emotions occurs in beverage consumption, regardless of the type of beverage product, since pleasant or positive emotions are primarily associated with beverages’ consumption. The analysis suggests that individuals predominantly associate beverages with pleasant emotions, regardless of the type of beverage, while the level of alcohol content seems to be influencing the different emotions and affect. The research results provide valuable insights to help managers and marketers understand the choice and preference for different beverages.

The Evaluation of Dark Chocolate-Elicited Emotions and Their Relation with Physico Chemical Attributes of Chocolate

The aim of this study was to evaluate the effect of different origin (Venezuela, Ghana, Peru) dark chocolates on emotions induced for consumers, and to analyse the relationships among overall acceptability (OA), emotions, and physicochemical attributes of the chocolate (fatty acids (FAs) and volatile compounds (VC)). Chocolate-elicited emotions were measured with FaceReader 8 software, scaling 10 emotion patterns (neutral, happy, sad, angry, surprised, scared, disgusted, contempt, valence, arousal). The OA was carried out by using a 10-point hedonic scale, ranging from 1 (extremely dislike) to 10 (extremely like). The obtained results showed that, among all chocolate-elicited emotions, the intensity of “happy” was the highest. In most cases, the influence of the different origin chocolate on the emotions induced for consumers was significant (except on emotions “neutral”, “scared”, and “disgusted”). Significant differences between the tested chocolates OA were not found. The origin of chocolate had a significant effect on most of the identified VC and the content of the main FAs (methyl palmitate, methyl stearate, cis,trans-9- oleic acid methyl ester, and methyl linoleate). Significant correlations between chocolate-elicited emotions and separate FAs and VC were found. Finally, this study showed that the origin of dark chocolate significantly influenced most of chocolate-elicited emotions and physicochemical attributes of chocolate, while separate FAs or VC can be used as chocolate quality indicators related to the chocolate OA, as well as chocolate-elicited emotions.

Influences of sensory attribute intensity, emotional responses, and non-sensory factors on purchase intent toward mixed-vegetable juice products under informed tasting condition

Product-related sensory and non-sensory cues have been studied in the past to understand purchase behavior among consumers. However, there has been little research related to integrating emotional responses with such cues to achieve better prediction of consumer purchase behavior. This study aimed to determine the impacts of sensory attribute intensities (SAI), non-sensory factors (NSF), and emotions on purchase intent and consumer choice. Emotional responses were measured using a self-reported emotion questionnaire (EQ), facial expression analysis (FE), and autonomic nervous system responses (ANS). Sixty-nine adults were asked to view product labels, and look at, smell, and drink five commercially-available vegetable juice samples. For each sample, SAI, NSF, EQ, FE, ANS, and purchase intent ratings were measured. Participants were also asked to select the one they would be most likely to buy. Results showed that the five samples differed significantly with respect to SAI, NSF, and emotional responses measured by EQ and FEs. SAI (bitterness intensity) and NSF (brand liking) played an extremely important role in purchase-related behavior of vegetable juice products. Correlation analysis and a PLSR prediction model further revealed that products with higher ratings of purchase intent elicited lower levels of negative emotions and higher levels of positive emotions, as measured by EQ as well as FE. In conclusion, this study shows that NSF in combination with SAI and emotions measured using EQ and FE can modulate consumer purchase intent toward vegetable juice products under informed tasting conditions.

Explicit and Implicit Responses to Tasting Drinks Associated with Different Tasting Experiences

Probing food experience or liking through verbal ratings has its shortcomings. We compare explicit ratings to a range of (neuro)physiological and behavioral measures with respect to their performance in distinguishing drinks associated with different emotional experience. Seventy participants tasted and rated the valence and arousal of eight regular drinks and a “ground truth” high-arousal, low-valence vinegar solution. The discriminative power for distinguishing between the vinegar solution and the regular drinks was highest for sip size, followed by valence ratings, arousal ratings, heart rate, skin conductance level, facial expression of “disgust,” pupil diameter, and Electroencephalogram (EEG) frontal alpha asymmetry. Within the regular drinks, a positive correlation was found between rated arousal and heart rate, and a negative correlation between rated arousal and Heart Rate Variability (HRV). Most physiological measures showed consistent temporal patterns over time following the announcement of the drink and taking a sip. This was consistent over all nine drinks, but the peaks were substantially higher for the vinegar solution than for the regular drinks, likely caused by emotion. Our results indicate that implicit variables have the potential to differentiate between drinks associated with different emotional experiences. In addition, this study gives us insight into the physiological temporal response patterns associated with taking a sip.

Development of emotion lexicons to describe chocolate using the Check-All-That-Apply (CATA) methodology across Asian and Western groups

Emotion-based terms selected by Asians and Westerners were analyzed to develop lexicons associated with chocolate consumption. Hence, an online-based questionnaire (Study 1: N = 206; 51% Asians, 49% Westerners) and a chocolate (milk and dark) tasting session (Study 2: N = 75; 52% Asians, 48% westerners) were conducted to assess emotion terms related to chocolate consumption using Check-All-That-Apply methodology. Emotional satisfaction was the main reason for chocolate consumption. Furthermore, selection of emotional terms was different between cultures and gender. For both studies (1 and 2), flavor of chocolate was the most important factor that determined purchase intention. For Study 2, milk and dark chocolate evoked different emotion terms for participants. The lexicon developed for milk chocolate had similar emotion terms compared to the Study 1 lexicon (online). Developing an emotion lexicon using an online survey could provide a reduced lexicon compared to lexicons generated during the tasting session and can be used as a fast-screening method to develop simplified emotion lexicons due to its similarity to the tasting lexicon. Newly developed lexicons from this study can be applied to sensory consumer tests of chocolate.

Methods for Evaluating Emotions Evoked by Food Experiences: A Literature Review

Besides sensory characteristics of food, food-evoked emotion is a crucial factor in predicting consumer's food preference and therefore in developing new products. Many measures have been developed to assess food-evoked emotions. The aim of this literature review is (i) to give an exhaustive overview of measures used in current research and (ii) to categorize these methods along measurement level (physiological, behavioral, and cognitive) and emotional processing level (unconscious sensory, perceptual/early cognitive, and conscious/decision making) level. This 3 × 3 categorization may help researchers to compile a set of complementary measures (“toolbox”) for their studies. We included 101 peer-reviewed articles that evaluate consumer's emotions and were published between 1997 and 2016, providing us with 59 different measures. More than 60% of these measures are based on self-reported, subjective ratings and questionnaires (cognitive measurement level) and assess the conscious/decision-making level of emotional processing. This multitude of measures and their overrepresentation in a single category hinders the comparison of results across studies and building a complete multi-faceted picture of food-evoked emotions. We recommend (1) to use widely applied, validated measures only, (2) to refrain from using (highly correlated) measures from the same category but use measures from different categories instead, preferably covering all three emotional processing levels, and (3) to acquire and share simultaneously collected physiological, behavioral, and cognitive datasets to improve the predictive power of food choice and other models.

Physico-chemical and sensory properties of marmalades made from mixtures of fruits and under-exploited Andean tubers

BACKGROUND

This work studies the added value to the Andean tuber crops through the production of jams. The objective were: (1) to study the sensory and instrumental characteristics of dietetic marmalades made with fruits and Andean tubers; (2) to research consumer's acceptability and emotional responses; (3) to assess the relationship between sensory and instrumental variables and (4) to determine sensory, instrumental and emotional variables that influence the acceptability.

RESULTS

Pearson's correlations showed that spreadability was the variable better predicted by sensory and instrumental ones. The analysis of variance showed that sourness increased with the increase of strawberry and the decrease of apple contents (P < 0.05). The acceptability increased when the strawberry proportion was higher. The sweetness-sourness balance drove the hedonic response and some emotions changed from one feeling to its corresponding opposite when the strawberry proportion reached 50 or 60. According to a partial least square 2 and a principal components analysis of sensory/acceptability/emotion data, 'typical', 'autochthonous', 'urban' and 'present' resulted in positive emotions which favored the consumer liking.

CONCLUSION

Formulating marmalades with mixtures of fruits and Andean tubers will allow giving value-added to these crops. The elaboration of products using innovative raw materials will be an incentive for farmers to cultivate them. © 2017 Society of Chemical Industry.

Spices in a Product Affect Emotions: A Study with an Extruded Snack Product †

Food commonly is associated with emotion. The study was designed to determine if a spice blend (cinnamon, ginger, nutmeg, and cloves) high in antioxidants can evoke changes in consumer emotions. This was an exploratory study to determine the effects of these four spices on emotions. Three extruded, dry snack products containing 0, 4, or a 5% spice blend were tested. One day of hedonic and just-about-right evaluations (n = 100), followed by three days of emotion testing were conducted. A human clinical trial (n = 10), using the control and the 4% samples, measured total antioxidant capacity and blood glucose levels. The emotion “Satisfied” increased significantly in the 5% blend, showing an effect of a higher spice content. The 4% blend was significantly higher in total antioxidant capacity than the baseline, but blood glucose levels were not significantly different.

Predicting consumer liking and preference based on emotional responses and sensory perception: A study with basic taste solutions

Traditional methods of sensory testing focus on capturing information about multisensory perceptions, but do not necessarily measure emotions elicited by these food and beverages. The objective of this study was to develop an optimum model of predicting overall liking (rating) and preference (choice) based on taste intensity and evoked emotions. One hundred and two participants (51 females) were asked to taste water, sucrose, citric acid, salt, and caffeine solutions. Their emotional responses toward each sample were measured by a combination of a self-reported emotion questionnaire (EsSense25), facial expressions, and autonomic nervous system (ANS) responses. In addition, their perceived intensity and overall liking were measured. After a break, participants re-tasted the samples and ranked them according to their preference. The results showed that emotional responses measured using self-reported emotion questionnaire and facial expression analysis along with perceived taste intensity performed best to predict overall liking as well as preference, while ANS measures showed limited contribution. Contrary to some previous research, this study demonstrated that not only negative emotions, but also positive ones could help predict consumer liking and preference. In addition, since there were subtle differences in the prediction models of overall liking and preference, both aspects should be taken into account to understand consumer behavior. In conclusion, combination of evoked emotions along with sensory perception could help better understand consumer acceptance as well as preference toward basic taste solutions.

The effect of the research setting on the emotional and sensory profiling under blind, expected, and informed conditions: A study on premium and private label yogurt products

Although sensory and emotional evaluation of food products mostly occurs in a controlled laboratory environment, it is often criticized as it may not reflect a realistic situation for consumers. Moreover, products are mainly blind evaluated by participants, whereas external factors such as brand are often considered as key drivers of food choice. This study aims to examine the role of research setting (central location test versus home-use test) and brand information on the overall acceptance, and sensory and emotional profiling of 5 strawberry-flavored yogurts. Thereby, private label and premium brands are compared under 3 conditions: blind, expected, and informed (brand information). A total of 99 adult subjects participated in 3 sessions over 3 consecutive weeks. Results showed that overall liking for 2 yogurt samples was higher in the laboratory environment under the informed evaluation condition, whereas no effect of research setting was found under the blind and expected conditions. Although emotional profiles of the products differed depending on the research setting, this was less the case for the sensory profiles. Furthermore, brand information clearly affected the sensory perception of certain attributes but had less influence on overall liking and emotional profiling. These results indicate that both scientists and food companies should consider the effect of the chosen methodology on ecological validity when conducting sensory research with consumers because the laboratory context could lead to a more positive evaluation compared with a home-use test.