One of the main functions of olfaction is to activate approach/avoidance behavior, toward or away from people, foods, or other odor sources. These behaviors are partly automated and therefore poorly accessible via introspection. Explicit tests need therefore be complemented by implicit tests to provide additional insights into the underlying processes of these behaviors. Affective responses to seven food odors plus one control nonodor were assessed in 28 female participants (1830 years) using explicit tests [pleasantness, intensity, and non-verbal emotional ratings (PrEmo)] as well as implicit tests that reflect dynamic expressive emotional reactions (facial expressions) as well as behavioral-preparation responses (autonomic nervous system responses: heart rate, skin conductance, and skin temperature). Explicit tests showed significant differences in pleasantness (P < 0.05), and all PrEmo emotions (P < 0.05) except shame. Explicit emotional responses were summarized by valence (explaining 83% of the responses variance) and arousal (14%) as principal components. Early implicit facial and ANS responses (after 1 s) seem to reflect the odors' arousal, whereas later ANS responses (after 3-4 s) reflected the odors' valence. The results suggest that explicit measures primarily reflect the odors' valence, as result of from relatively long (conscious) processing, which may be less relevant for odor acceptance in the real world where fast and automated processes based on arousal may play a larger role.

Traditional sensory and hedonic tests are often limited to predict market performance. Investigating emotional responses to food stimuli may contribute to a better understanding of consumers’ eating behavior. In the present study, 26 female participants were exposed to an orange (pleasant) and a fish (unpleasant) odor presented in three different concentrations perceived as weak, medium and strong intensity in a semi-random order via an olfactometer. Emotional responses to those food odors were measured discretely using non-verbal subjective reports, and continuously using facial expressions. Non-verbal reports reflected primarily the odor’s valence with positive emotions, such as joy, satisfaction and hope, related to orange and negative emotions, such as dissatisfaction, fear and disgust, related to fish. Facial expressions varied dynamically over the 4s following stimulation, whereby expressions at 1250 and 2000ms associated best with odor valence and odor intensity, respectively. The correlation between non-verbal subjective reports and facial expressions reached a maximum during the second sec after exposure. Pleasant odors were associated with neutral and surprised expressions, and with fewer expressions of disgust. More intense odors were associated with fewer neutral expressions and more expressions of disgust. Facial expressions reflect the dynamic sequential unfolding of different emotional responses, whereas non-verbal reports primarily reflect the end result of valence appraisal. The distinction between initial and subsequent reactions detected by facial expressions may offer a new valuable perspective for sensory and consumer research.

As a food is consumed, its perceived pleasantness declines compared to that of other foods. Although this phenomenon, referred to as sensory-specific satiety, is well-established by means of measuring food intake and pleasantness ratings, this study was aimed at gaining more insight into the mechanisms that underlie such cognitive output behavior using two measures used in (food) emotion research, namely Autonomic Nervous System (ANS) responses and facial expressions. Twenty-four healthy female participants visited four times in a hungry state, in which they received 4 different semi-liquid meals (2 sweet and 2 savory) delivered via a time-controlled pump leading to sensory-specific satiety. Before and after the meals they were presented with a sip of all four different test meals where ANS responses (heart rate, skin conductance and skin temperature) and facial expressions were recorded. As expected, pleasantness ratings showed a significant decrease after eating the same meal or a meal similar in taste (sweet or savory) (p<0.001), and less decrease after eating a meal with a different taste. In general, consumption of the test meals resulted in increased heart rate, reduced skin conductance and skin temperature, as well as intensified anger and disgusted facial expressions (p<0.05). In addition, skin conductance, skin temperature, sad and angry expressions also showed effects reflecting sensory-specific satiety. In conclusion, ANS responses and facial expressions indicate that sensory specific satiety of foods 1) not only reduces the food's pleasantness but also arousal and 2) are possibly mediated by changes in food emotions.

The high failure rate of new market introductions, despite initial successful testing with traditional sensory and consumer tests, necessitates the development of other tests. This study explored the ability of selected physiological and behavioral measures of the autonomic nervous system (ANS) to distinguish between repeated exposures to foods from a single category (breakfast drinks) and with similar liking ratings. In this within-subject study 19 healthy young adults sipped from five breakfast drinks, each presented five times, while ANS responses (heart rate, skin conductance response and skin temperature), facial expressions, liking, and intensities were recorded. The results showed that liking was associated with increased heart rate and skin temperature, and more neutral facial expressions. Intensity was associated with reduced heart rate and skin temperature, more neutral expressions and more negative expressions of sadness, anger and surprise. Strongest associations with liking were found after 1 second of tasting, whereas strongest associations with intensity were found after 2 seconds of tasting. Future studies should verify the contribution of the additional information to the prediction of market success.

In our food abundant environment, food cues play an important role in the regulation of energy intake. Odours can be considered as external cues that can signal energy content in the anticipatory phase of eating. This study aims to determine whether exposure to olfactory cues associated with energy dense foods leads to increased food intake and greater preference for energy-dense foods. In addition, we assessed whether BMI and hunger state modulated this effect.Twenty-five overweight (mean BMI: 31.3kg/m2, S.E.: 0.6) and 25 normal-weight (mean BMI: 21.9kg/m2, S.E.: 0.4) females, matched on age and restraint score, participated. In 6 separate sessions they were exposed to odours of three different categories (signalling non-food, high-energy food and low-energy food) in two motivational states (hungry and satiated). After 10min of exposure food preference was assessed with a computerized two-item forced choice task and after 20min a Bogus Taste Test was used to determine energy intake (kcal and g).In a hungry state, the participants ate more (p<.001) and preferred high-energy products significantly more often (p<.001) when compared to the satiated state. A trend finding for the interaction between hunger and BMI suggested that the food preference of overweight participants was less affected by their internal state (p=.068). Neither energy intake (kcal: p=.553; g: p=.683) nor food preference (p=.280) was influenced by ambient exposure to odours signalling different categories.Future studies need to explore whether food odours can indeed induce overeating. More insight is needed regarding the possible influence of context (e.g. short exposure duration, large variety of food) and personality traits (e.g. restraint, impulsive) on odour-induced overeating.

Why we like or dislike certain products may be better captured by physiological and behavioral measures of the autonomic nervous system (ANS) than by conscious or classical sensory tests. Responses to pleasant and unpleasant food odors presented in varying concentrations were assessed continuously using facial expressions and responses of the ANS. Results of 26 young and healthy female participants showed that the unpleasant fish odor triggered higher heart rates and skin conductance responses, lower skin temperature, fewer neutral facial expressions and more disgusted and angry expressions (p < 0.05). Neutral facial expressions differentiated between odors within 100 ms, after the start of the odor presentation followed by expressions of disgust (180 ms), anger (500 ms), surprised (580 ms), sadness (820 ms), scared (1020 ms), and happy (1780 ms) (all p-values < 0.05). Heart rate differentiated between odors after 400 ms, whereas skin conductance responses differentiated between odors after 3920 ms. At shorter intervals (between 520 and 1000 ms and between 2690 and 3880 ms) skin temperature for fish was higher than that for orange, but became considerable lower after 5440 ms. This temporal unfolding of emotions in reactions to odors, as seen in facial expressions and physiological measurements supports sequential appraisal theories.

The studywas conducted to analyse the correlation between the sensory attributes and chemical components of black and green tea. Different kinds of black and green tea were chosen to study the key factors in the tea quality. By sensory evaluation and correlation analysis on various quality factors (appearance, aroma, liquor color, taste and infused leaves), taste was determined as the key factor. Ten taste attributes (heavy flavor, thick flavor, sweet flavor, fresh flavor, mellow flavor, astringency, tenderness, stale flavor, purity and fired flavor) was determined to evaluate taste profiles by yardstick estimation method. The contents of the three main flavor substances (polyphenols, caffeine, theanine) were determined. By the differently significant analysis of ten taste attributes among various tea and the correlated analysis between flavor profiles and the three flavor components, the freshness and astringency were dominated by the contents of theanine and caffeine respectively, and were the main differences of various tea species. This study established a method for tea grading and quantitative analysis on tea sensory quality.

Consumer food choice and intake are largely controlled by unconscious processes, which may be reflected better by implicit physiological and behavioural measures than by the more traditional explicit sensory tests. In this study, 26 human participants were exposed to an orange (pleasant) and a fish (unpleasant) odour presented in three different concentrations perceived as weak, medium and strong intensity, and five replications in a semi-random order via an olfactometer (Burghart OM2). Reactions to these odours were measured implicitly by means of facial expressions (automatically analysed with FaceReader), skin conductance responses and heart rate frequency (automatically analysed by Biolab), and explicitly with pleasantness ratings. Facial expressions reflected the odour’s valence (71% explained variance) and ranged from neutral (orange) to sadness/disgust/anger (fish) but showed additional differentiation with respect to odour intensity (15% explained variance). Skin conductance responses were largest for the unpleasant odour (p < 0.05), but showed no intensity effect. The unpleasant odour resulted in increased heart rate whereas the pleasant odour resulted in reduced heart rate (p < 0.05). The heart rate effects increased with intensity (p < 0.05). Different degrees of exposure were reflected in the implicit behavioural and physiological tests but not in the explicit pleasantness test. In summary, implicit physiological and behavioural responses provide detailed information on specific food odours that may not be provided by other more explicit tests.

The relationship between sensory and instrumental measurements of tea was investigated.Research was conducted to compare tea quality measured by a trained sensory panel and instrument analysis using electronic tongue.The electronic tongue was used in combination with principal component analysis (PCA) for the classification of tea samples from three quality grades.Results from these analysis demonstrated that tea samples with different quality grades can be separated clearly by electronic tongue.Electronic tongue can be also used to determine the electronic tongue sensors that were best correlated with sensory evaluation and provide the objective results in estimating tea quality.

Research was conducted to compare tea quality measured by a trained sensory panel and instrument analysis using a potentiometric sensor array. This array is formed by a set of non-specific all-solid-state potentiometric sensors and has been used in combination with principal component analysis (PCA) for the classification of tea samples from different geographical origins and quality grades. The method used to assess 10 sensory attributes in tea taste such as heavy flavor, thick flavor, sweet flavor, fresh flavor, mellow flavor, astringency, tenderness, stale flavor, purity and fired flavor were in accordance to the China National Institute of Standardization (CNIS) sensory profile test. The relationship between instrumental and sensory measurements of tea was also investigated. Results from these analyses demonstrate that the electronic tongue can be used to predict sensory characteristics and their relationship to the taste quality of tea measured by professional taster.