Odour liking physiological indices: a correlation of sensory and electrophysiological responses to odour

The perception of smell is dominated by an hedonic dimension, with changes in left and right orbitofrontal activation evident in responses to odours of different valence. Electrophysiological (EEG) recordings were used to investigate differences in hemispheric activation associated with different hedonic responses to a low concentration of a single compound (damascenone: fruity, berry smell). Stimulus delivery (air, or air with odour) was synchronised with inspiration using a continuous respiration olfactometer. EEG responses were analysed using traditional power spectrum techniques to determine the relationship of the brain activity to the reported odour liking responses. Differences in response to the odour were evident in comparison with air, and also between response groups. Using the same odour to evoke different hedonic responses, power spectrum analysis revealed a non-significant trend for left frontal differences in EEG associated with different liking responses to damascenone. This demonstrated quantification of the neurophysiological effects associated with odour liking.     

Application of a written scenario to evoke a consumption context in a laboratory setting: Effects on hedonic ratings

Consumer hedonic testing of products is typically conducted under controlled sensory laboratory conditions. This setting does not accurately represent how food and drink are consumed. Literature demonstrates that consumer hedonic ratings elicited in the natural consumption context differ to those elicited under controlled conditions. This suggests that when removing a product from its natural consumption context, accurate hedonic ratings may not be obtained. The interest of this research was to develop an approach that evokes a consumption context in the sensory laboratory and study its impact on hedonic ratings. A written scenario was developed that was effective at making participants imagine an occasion when they desired a refreshing beverage. Consumer hedonic ratings of four apple juice samples elicited using the evoked consumption context (context condition) were compared to those elicited in a control condition (i.e., no evoked context). Differences in mean hedonic ratings of the samples were observed between the two conditions with greater sample discrimination observed for the evoked context condition. Consumers using the evoked context found it easy to indicate their product liking/disliking, and felt that the liking information they provided was accurate, more so than consumers in the control setting. Sensory practitioners need to be aware of the potential use of an evoked context in a control setting for eliciting product hedonic ratings, and understand its impact on mean hedonic ratings.     

A new approach to measuring Overall Liking with the Many-Facet Rasch Model

The 9-point hedonic scale is the most common hedonic rating scale used to provide an assessment of overall liking. Studies have shown that consumer judgements of overall liking could be influenced by their ratings of the liking of flavour, texture, aroma or appearance. However, this is not directly taken into account when using the holistic variable of overall liking. A new approach is proposed for measuring overall liking that is firstly based on initially considering what sensory characteristics (attributes or modalities) defines the latent sensory construct of OVERALL LIKING. The aim of this study was to develop a single measure of Overall Liking that incorporates the relative importance of liking ratings from different sensory characteristics by applying a Many-Facet Rasch model to produce interval-scaled estimates of Overall Liking. A homogeneity test found significant differences (p < 0.01) between the Rasch means estimates of the cured 10 hams that were evaluated by a consumer panel (n = 90), with the two different definitions of the Rasch measure of Overall Liking. No significant differences were found when comparing Rasch measures with raw scores using an intrablock BIB ANOVA and Durbin test. The degree of Relevance, shown on a Many-Facet Wright map, indicated the extent which a variable contributed to the measure of Overall Liking. Of the 10 sensory attributes used for the Individual Attribute Measure, Hardness and Juiciness contributed the most, while Sweetness and Typical Flavour contributed the least. However, the modalities used in rating the Likings of Overall Flavour, Texture, Aroma and Appearance contributed almost to the same extent to Overall Liking in the Total Attribute Measure. The Wright Map also showed that the categories on the 9-point hedonic scale were unequally spaced and the distance between them became increasingly larger the further away from the central category of ‘Neither like nor dislike’.     

Does Information about Sugar Source Influence Consumer Liking of Products Made with Beet and Cane Sugars?

Beet sugar contains an off‐aroma, which was hypothesized to generate expectations on the acceptability of a product made with beet sugar. Thus, the objective of this study was to assess the impact of information about the sugar source (beet vs. cane) on the overall liking of an orange‐flavored beverage. One hundred panelists evaluated an orange‐flavored powdered beverage mix and beverage made with beet and cane sugars using a 5‐phase testing protocol involving a tetrad test and hedonic ratings performed under blind and informed conditions. Tetrad test results indicated that there was a significant difference (P < 0.05) between the beverage mix made with beet sugar and cane sugar; however, no difference was found between the beverage made with beet sugar and cane sugar. Hedonic ratings revealed the significance of information conditions on the panelists evaluation of sugar (F = 24.67, P < 0.001); however, no difference in the liking was identified for the beverage mix or beverage. Average hedonic scores were higher under informed condition compared to blind condition for all products, possibly because labels tend to reduce uncertainty about a product. Results from this study are representative of the responses from the general population and suggest that they are not affected by sugar source information in a beverage product. Based on concerns with the use of beet sugar expressed in the popular press, there may be a subgroup of the population that has a preconceived bias about sugar sources due to their prior experiences and knowledge and, thus, would be influenced by labels indicating the sugar source used in a product.     

Co-acting strangers but not friends influence subjective liking and facial affective responses to food stimuli

In recent years, consumers' emotional responses have been found to be an important complement to sensory and hedonic evaluations for the prediction of food choice and consumption behaviour. Given this trend, it is essential that the influence of contextual variables on emotion are investigated. The present study contributes to the discussion with an investigation of the effect of social context on implicit emotional responses to food images. 87 participants (56 female, 31 male) viewed food images of varying acceptability either alone, with a stranger, or with a friend. Subjective liking ratings were measured using a labelled affective magnitude scale, and facial muscle activity from zygomaticus major (contracted during smiling), corrugator supercilii (contracted during frowning) and levator labii superioris (contracted during nose wrinkling) were measured with an EMG recording system. Controlling for individual differences in facial expressivity and food image acceptability using linear mixed models, it was found that the presence of a co-acting stranger facilitated muscle activity indicative of a disgust response, increased the strength of relationship between muscle activity and subjective liking ratings, and led to lower subjective liking overall. No differences in muscle activity or subjective liking were found between subjects who participated alone and with a co-acting friend. This suggests that the influence of social context is complex, where the relationship between the subject and the social environment can impact both hedonic and emotional evaluations of food stimuli. These findings indicate that facial EMG can be a useful dynamic and implicit measure of emotion in consumer research, but it is critical to consider the social context of the testing environment.     

The importance of liking of appearance, -odour, -taste and -texture in the evaluation of overall liking. A comparison with the evaluation of sensory satisfaction

The response variable of overall liking is often used to measure consumers’ overall hedonic response to food. However, little research is done to understand, if liking of all four sensory modalities; appearance, odour, taste and texture, are reflected in the evaluation of overall liking, or if a single sensory modality stands out and is of most importance. The term sensory satisfaction was recently introduced as an alternative to overall liking and should (at least in theory) be used by consumers as a more holistic response variable than overall liking. The aim of the analyses reported in the present paper were, to study the importance of the sensory modalities (liking of appearance, odour, taste and texture) in consumers’ evaluation of overall liking and compare the findings to the importance of the sensory modalities (liking of appearance, odour, taste and texture) in consumers’ evaluation of sensory satisfaction. The data came from a cross-over consumer case-study on apple-cherry fruit drinks (n = 67). The fruit drinks varied in: type of sweetener used, and addition of aroma and fibre. The modalities driving overall liking and sensory satisfaction were studied through slopes of a regression line relating overall liking and sensory satisfaction, respectively, to liking of the sensory modalities: liking of appearance, -odour, -taste and -texture. Results showed the steepest slope between overall liking and liking of taste, whereas the least steep slope was found for liking of odour. The same pattern between slopes was found for sensory satisfaction and overall liking. Therefore, it was concluded that consumers primarily paid attention to liking of taste (to be understood as flavour) and least attention to liking of odour, when evaluating overall liking and sensory satisfaction, respectively, and that consumers did not use sensory satisfaction as a more holistic response variable than overall liking.     

Creating memorable products: Actual liking and remembered liking

Product choice is influenced by the remembered liking for that product at the time that the choice is made. Little research has been carried out on memory for the liking of foods, and yet remembered liking at the time of purchase may be more influential on choice than liking ratings obtained during actual product consumption. A recent study examines how liking ratings made during consumption are integrated to produce an overall remembered evaluation. Its results enable quantifying differences between actual and remembered liking experiences.

Introduction

Product choice is partly influenced by the remembered liking for that product at the time of consumption. The relationship between actual and remembered liking has received almost no attention in the food literature. How do my hedonic responses, made ‘on-line’ as I consume the product, become integrated to form a holistic retrospective memory? If we understood this process, we could design products so as to maximize remembered liking in order to ensure repeat purchase and use.From pain research it is known that the pattern of the pain intensity interferes with memory: an acute pain pattern with a peak just before the end of the pain experience scores higher on remembered pain intensity than a chronic pain pattern with no peak at the end (the so-called ‘peak-at-end effect’; Ariely, 1998 and Kahneman et al., 1993). The present study was an initial attempt to extrapolate these negative effect findings from pain research to the positive affective experiences in the food domain. We hypothesised that products that deliver the maximum of the sensory stimuli at the end (peak-at-end rule) of the eating experience will score higher on remembered liking than products that follow a constant or a different liking pattern. The food product used was a crunchy cheese snack filled with soft processed cheese. The cheese filling varied in salt and cheese flavour intensity (Low and High) to examine four different sensory patterns: (1) a high constant pattern, (2) a low constant pattern, (3) a peak-at-end pattern and (4) a drop-at-end pattern (see Table 1).     

Assessment of commercial lamb meat quality by British and Spanish taste panels

Trained sensory panels in Britain and Spain assessed loin meat from commercial lambs purchased in Spain, which included Welsh lamb (imported from Britain) and two Spanish breeds (Merino and Rasa Aragonesa). The British panel also assessed British lamb purchased in local butcher shops and supermarkets. Sensory panels, in each country, received meat from the same lambs and used their local methods of cooking and assessment. Spanish panels used unstructured line scales to measure lamb odour intensity, tenderness, juiciness, lamb flavour intensity and two hedonic scales of flavour liking and overall liking. The British panel used 8 point category scales with the same attributes. Results from both panels in objective parameters were in agreement, hence showing that different trained sensory panels may arrive at the same conclusion. However, when panellists were allowed to make hedonic judgements (preference), the British panel preferred British lamb and the Spanish panel preferred Spanish lamb. This finding has important consequences for lamb producers who export their lambs and demonstrates that the underlying reasons for different preferences should be investigated. Production variables are discussed in relation to their influence on lamb eating quality and as a way to tailor lamb eating quality attributes familiar to consumers in the importing country.     

CONSUMER TEXTURE PREFERENCES: EFFECT OF AGE, GENDER AND PREVIOUS EXPERIENCE

Four different strawberry candies with varying thickening agents (pectin, gelatin, starch, and gelatin + starch) were rated by three consumer age groups: teenagers (13–14 years), young adults (19–23 years) and the middle-aged (40–63 years) (n = 60 in each group). Age, gender, use frequencies and hedonic ratings often commercial candy types were collected as background information. Four preference groups were found by using preference mapping. The most important factor predicting preference of a sample were hedonic evaluations of commercial candies whose texture was similar to that of the test sample. If the consumers gave high hedonic ratings to one sample they also tended to report liking for the commercial candy with a similar texture. Age and gender also affected hedonic evaluations in most cases. For example, the middle-aged consumers were more clearly segmented into different preference groups than were the two younger groups. Use frequencies of commercial candies had no statistically significant effect on sample preference. We conclude that, in the case of candy, consumers' preferences can be explained by the liking of commercial candies with similar texture. Also, age and gender may have significant effects.     

Reaction to boar odour by different South African consumer groups

A consumer sensory study of South African pork consumers (n=300) including equal numbers of males and females and consumers from three ethnic groupings (black, white and coloured consumers) was conducted to determine the effects of gender and ethnicity on consumer reactions towards boar odour compounds. Samples consisted of boar fat with varying concentrations of skatole and androstenone. Each consumer evaluated the odour of seven fat samples. Consumers’ liking of pork meat in general had a significant effect on the hedonic rating of the boar odour. The majority of consumers represented in this study would be dissatisfied with pork meat exhibiting detectable levels of skatole. In general, more females compared with males, will also respond more negatively towards samples with detectable levels of androstenone. An apparent liking for samples with medium levels of androstenone (0.5–1 μg/g) was found for some consumers, especially males, and can be partly attributed to the inability of some consumers to smell this compound at these levels or a genuine liking for the odour of androstenone. Significant differences in the sensitivity of consumers from different ethnic groups were found with white females responding more negatively than white males and blacks. Although it was not possible to compare responses directly with the white and black groups, it was found that a higher percentage of coloureds responded negatively to boar odour compounds. Coloured males responded particularly negatively towards samples with detectable skatole, while black males, in general, were found to be more critical than black females. Based on these results it is predicted that the majority of consumers would be less willing to consume pork meat exhibiting detectable levels of boar odour.     

That smells filling: Effects of pairings of odours with sweetness and thickness on odour perception and expected satiety

Retronasal co-experience of odours with sweet tastes and thick textures have been shown to result in attribution of sweetness and thickness to odours when they are subsequently sniffed. Orosensory thickness and creaminess are also associated with expectations that a product will be filling. Here we test for the first time whether co-experience of odours with orosensory thickness and sweetness results in transfer of satiety expectations to these odours when subsequently sniffed. Eighty healthy volunteers evaluated the hedonic and sensory characteristics of odours, and expectations that products with the same flavour as the odour would be filling, before and after disguised co-experience of odours with sweetness (sucrose), thickness (tara gum solution) or the combination of sweet/thick, as well as untrained (control) odours. Odours paired with tara gum were subsequently rated as smelling thicker and more creamy, while odours paired with sucrose smelled sweeter. Pairing odours with tara gum increased the expectation that products predicted to have the same flavour as the sniffed odour would be more filling, and this was enhanced by sweetness, while pairing odours with tara-gum increased the expectation that products with that odour would reduce later hunger. Liking for odours paired with sweetness increased, but pairing with thickness alone reduced liking. These data suggest that satiety-consonant sensory characteristics can transfer to associated odours, and that this process is independent of changes in liking. This raises the possibility of using satiety-associated odour cues to manipulate consumer satiety expectations.     

Colour and shape of design elements of the packaging labels influence consumer expectations and hedonic judgments of specialty coffee

Packaging plays an important role on attracting the consumers’ attention and creating hedonic and sensory expectations, which may affect actual product experience. The present study aimed at investigating whether the colour and/or shape of design elements of packaging labels would influence sensory and hedonic judgments of specialty coffee by amateur consumers. Participants (n = 174) first evaluated their expectations of coffee acidity and sweetness by looking at the coffee package, and subsequently, their experience of the same attributes when tasting a cup of coffee, in addition to rating their liking and purchase intent. The experiment followed a 2 × 2, between-subject design for label type (green or pink, round or angular), and the same coffee was served to all participants. Multivariate analysis of variance was conducted in order to assess main effects of colour and shape of the design elements of the packaging labels as well as interactions on sensory and hedonic ratings. Both colour and shape significantly affected consumers’ sensory expectations (pre-tasting ratings) regarding the specialty coffee, but they had no significant effect on post-tasting (actual perception) sensory ratings. Interactions between colour × shape were found to affect the hedonic measures. The coffee associated with the congruent labels (i.e., angular/green or the round/pink) received higher liking and purchase intent ratings than the one associated with the incongruent labels (i.e., angular/pink and the round/green). The implications of these results for the design of coffee packaging that convey some functional benefit as well as possible directions for future research are discussed.     

Patterns of sweet liking in sucrose solutions and beverages

While preferred levels of sweetness are known to differ across individuals, investigations of hedonic responses to sweetness across multiple concentrations in both model system and beverage are limited. The objective of this study was to classify people according to their preferred sweetness in sucrose solutions and beverages. The stimuli were water and flavored beverages, each containing five levels of sucrose. A total of 200 female subjects rated liking and intensity of sweetness for sucrose solutions, and they conducted paired preference tests using the Monell forced-choice, paired-comparison, tracking procedure. These tests were replicated for the beverage. These evaluations were conducted on two separate occasions, once while the subjects were hungry and once relatively sated. Hierarchical cluster analysis revealed three distinct clusters based on the hedonic ratings. Cluster 1 showed positive hedonic ratings with increased sucrose concentration in both systems. Cluster 2 showed positive ratings to sucrose increases in the beverage, but not in the sucrose solution. Cluster 3 showed an inverted-U shaped pattern. These patterns were confirmed by the result of the Monell test. Similar trends were observed when the subjects were asked to rate liking of chocolates and in ratings of preferences for commonly consumed sweet and savory food items.     

The sensory optimum of chicken broths supplemented with calcium di-glutamate: A possibility for reducing sodium while maintaining taste

This study examined the effects of calcium di-glutamate (CDG) supplementation on the sensory and hedonic characteristics of chicken broth. Thirty-four normal weight men and women aged 20-35 years tasted 12 soups containing 4 different concentrations of sodium chloride (.16%, .53%, .85%, and 1.7% w/w) and three concentrations of CDG (0%, .17%, and .33% w/w). Participants tasted all the soups twice over 2 days and used computer-administered visual analog scales to record taste intensity and hedonic ratings. Soups were presented in random order, at least 3 min apart to allow for taste ratings and mouth rinsing. Data were analyzed using repeated measures analysis of variance. Response surface methodology (RSM) was used to determine the hedonic optima for sodium chloride and CDG. Results indicated that CDG could partly replace sodium chloride at constant levels of liking and pleasantness. These data provide evidence that lower sodium broths can be made more palatable with CDG supplementation.     

The effect of attribute questions on overall liking ratings

In food acceptance tests, it is typical for respondents to rate a product on overall liking and on a series of product attributes. This study was designed to determine if the inclusion of attribute questions can alter a respondent's rating of overall liking. Five groups of respondents evaluated four variations of a dairy dessert. Each group used a different questionnaire, comprised either of (a) overall liking only; (b) overall liking plus intensity scales, which asked respondents to rate the strength of 10 sensory characteristics; (c) overall liking plus attribute liking scales, which asked respondents to rate their liking of appearance, flavor and texture of the products; (d) overall liking plus just-about-right scales, which asked respondents to indicate whether the level of 10 sensory characteristics was “too high”, “too low”, or “just about right”; and (e) overall liking plus attribute liking and just-about-right scales. The inclusion of just-about-right questions on the questionnaire changed the average overall liking ratings of the products, whereas intensity scales had no such effect. Attribute liking questions also tended to alter overall liking ratings, but to a lesser extent than just-about-right questions. Several hypotheses concerning the source of these context effects are discussed.