Multidimensional measurement of individual differences in taste perception

Pomegranate Quality from Consumers' Perspective: Drivers of Liking, Preference Patterns, and the Relation between Sensory and Physico-Chemical Properties

Acquiring information on consumer preferences for the sensory properties of pomegranates is a cue for breeding programmes to set their quality targets and promote the consumption of this particularly healthy fruit. In this study, a total of 12 pomegranate varieties were evaluated, including commercial (Valenciana, Illina, Tastem, Rugalate, Wonderful, Mollar 49 y Mollar 45) and new varieties (Ref 102, Ref 383, H3/27, and D27/12). For the first time, consumers not only scored their acceptance of different pomegranate varieties but also described their sensory properties using CATA questions. This approach allowed us to identify the main drivers of liking, preference patterns, and the relationship between sensory and physico-chemical properties. Of all the sensory attributes, acidity intensity was revealed as the main driver of liking/disliking, and two different consumer preference patterns were identified: 'low acid pomegranate lovers' and 'acid pomegranate lovers'. Seed properties like the intensity of woody flavour and seed/aril ratio were also key drivers for preferences. A relationship between sensory and physico-chemical properties was also established. Interestingly, sweetness perception correlated more strongly with low titratable acidity levels than with high total soluble solids levels, corroborating that acidity level is a key measurement for quality assessments. 'H3/27' was the most promising of the new varieties for having the well-appreciated internal properties of the 'Mollar' varieties and external and internal red colouration, which makes it much more appealing to consumers. This study shows that there is still room on the market for pomegranate varieties with very different sensory properties and highlights the need to develop sensory labels that help consumers make the right choices.

Factors explaining individual differences in the oral perception of capsaicin, l-menthol, and aluminum ammonium sulfate

This research focused on the oral perception of naturally occurring chemical food compounds that are used in the pharma and food industries due to their pharmacological properties. They stimulate chemically sensitive receptors of the somatosensory system and are also chemesthetic compounds. Capsaicin is a naturally occurring alkaloid activating pungency perception. l-Menthol is a cyclic monoterpene working also as a medical cooling agent. Aluminum ammonium sulfate is used as a dehydrating agent and additive known to activate astringency in oral cavity. The objective of the study was to identify factors explaining individual differences in the perception of oral chemesthesis measured as sensitivity to chemesthetic compounds and their recognition. The subjects (N = 205) evaluated quality-specific prototypic compounds at five different concentration levels. Differences between gender were discovered in capsaicin sensitivity with men being less sensitive than women. Age was associated with the perception of capsaicin, l-menthol, aluminum ammonium sulfate, and the combined oral chemesthetic sensitivity. Quality-specific recognition ratings were also contributing to the sensitivity to chemesthetic compounds. A combined oral chemesthetic recognition score was created based on quality-specific recognition ratings. Increasing age generally indicated weaker recognition skills. Better recognizers had a higher combined oral chemesthetic sensitivity score than poorer recognizers. These results provide new information about chemesthesis. The results suggest that age and gender are important factors in explaining individual differences in sensitivity to capsaicin, l-menthol, and aluminum ammonium sulfate. In addition, recognition skills are associated with the sensitivity based on the quality-specific recognition scores.

Salivary microbial profiles associate with responsiveness to warning oral sensations and dietary intakes

Oral microbiota-host interactions are gaining recognition as potential factors contributing to interindividual variations in taste perception. However, whether such possible links imply specific bacterial co-occurrence networks remains unknown. To address this issue, we used 16 s rRNA gene sequencing to profile the salivary microbiota of 100 healthy individuals (52 % women; 18-30 y/o), who provided hedonic and psychophysical responses to 5 liquid and 5 solid commercially-available foods, each chosen to elicit a target sensation (sweet, sour, bitter, salty, pungent). The same cohort also completed several psychometric measures and a 4-day food diary. Unsupervised data-driven clustering of genus-level Aitchison distances supported the existence of two salivary microbial profiles (CL-1, CL-2). While CL-1 (n = 57; 49.1 % women) exhibited higher α-diversity metrics and was enriched in microbial genera assigned to the class Clostridia (e.g., Lachnospiraceae_[G-3]), CL-2 (n = 43; 55.8 % women) harbored greater amounts of taxa with potential cariogenic effects (e.g., genus Lactobacillus) and significantly lower abundances of inferred MetaCyc pathways related to the metabolic fate of acetate. Intriguingly, CL-2 showed enhanced responsiveness to warning oral sensations (bitter, sour, astringent) and a higher propensity to crave sweet foods or engage in prosocial behaviors. Further, the same cluster reported habitually consuming more simple carbohydrates and fewer beneficial nutrients (vegetable proteins, monounsaturated fatty acids). In summary, while the mediating role of participants' baseline diet on findings can not be definitively excluded, this work provides evidence suggesting that microbe-microbe and microbe-taste interactions may exert an influence on dietary habits and motivates further research to uncover a potential "core" taste-related salivary microbiota.

TDS Similarity: Outlier Analysis Using a Similarity Index to Compare Time-Series Responses of Temporal Dominance of Sensations Tasks

Temporal dominance of sensations (TDS) methods are used to record temporally developing sensations while eating food samples. Results of TDS tasks are typically discussed using averages across multiple trials and panels, and few methods have been developed to analyze differences between individual trials. We defined a similarity index between two time-series responses of TDS tasks. This index adopts a dynamic level to determine the importance of the timing of attribute selection. With a small dynamic level, the index focuses on the duration for attributes to be selected rather than on the timing of the attribute selection. With a large dynamic level, the index focuses on the temporal similarity between two TDS tasks. We performed an outlier analysis based on the developed similarity index using the results of TDS tasks performed in an earlier study. Certain samples were categorized as outliers irrespective of the dynamic level, whereas the categorization of a few samples depended on the level. The similarity index developed in this study achieved individual analyses of TDS tasks, including outlier detection, and adds new analysis techniques to TDS methods.

The Individual Differences in the Perception of Oral Chemesthesis Are Linked to Taste Sensitivity

Chemesthesis is a part of the flavor experience of foods. Chemesthetic perception is studied to understand its effect on food-related behavior and health. Thus, the objective of this research was to study individual differences in chemesthetic perception. Our study involved sensory tests of three chemesthetic modalities (astringency, pungency, and cooling). Participants (N = 196) evaluated the intensity of samples in different concentrations using a line scale under sensory laboratory conditions. Aluminum ammonium sulfate, capsaicin, and menthol were used as the prototypic chemesthetic compounds. The participants were divided into sensitivity groups in different chemesthetic modalities by hierarchical clustering based on their intensity ratings. In addition, an oral chemesthesis sensitivity score was determined to represent the generalized chemesthesis sensitivity. The results showed that people can perceive chemesthesis on different intensity levels. There were significantly positive correlations between (1) sensitivity scores for oral chemesthesis and taste as well as (2) each chemesthesis and taste modalities. Moreover, based on the multinomial logistic regression model, significant interactions between oral chemesthesis and taste sensitivity were discovered. Our findings showed that people can be classified into different oral chemesthesis sensitivity groups. The methods and results of this study can be utilized to investigate associations with food-related behavior and health.

Data-Driven Clustering Approach to Derive Taste Perception Profiles from Sweet, Salt, Sour, Bitter, and Umami Perception Scores: An Illustration among Older Adults with Metabolic Syndrome

BACKGROUND

Current approaches to studying relations between taste perception and diet quality typically consider each taste-sweet, salt, sour, bitter, umami-separately or aggregately, as total taste scores. Consistent with studying dietary patterns rather than single foods or total energy, an additional approach may be to study all 5 tastes collectively as "taste perception profiles."

OBJECTIVE

We developed a data-driven clustering approach to derive taste perception profiles from taste perception scores and examined whether profiles outperformed total taste scores for capturing individual variability in taste perception.

METHODS

The cohort included 367 community-dwelling adults [55-75 y; 55% female; BMI (kg/m2): 32.2 ± 3.6] with metabolic syndrome from PREDIMED-Plus, Valencia. Cluster analysis identified subgroups of individuals with similar patterns in taste perception (taste perception profiles); quantitative criteria were used to select the cluster algorithm, determine the optimal number of clusters, and assess the profiles' validity and stability. Goodness-of-fit parameters from adjusted linear regression evaluated the individual variability captured by each approach.

RESULTS

A k-means algorithm with 6 clusters best fit the data and identified the following taste perception profiles: Low All, High Bitter, High Umami, Low Bitter & Umami, High All But Bitter and High All But Umami. All profiles were valid and stable. Compared with total taste scores, taste perception profiles explained more variability in bitter and umami perception (adjusted R2: 0.19 vs. 0.63, respectively; 0.40 vs. 0.65, respectively) and were comparable for sweet, salt, and sour. In addition, taste perception profiles captured differential perceptions of each taste within individuals, whereas these patterns were lost with total taste scores.

CONCLUSIONS

Among older adults with metabolic syndrome, taste perception profiles derived via data-driven clustering may provide a valuable approach to capture individual variability in perception of all 5 tastes and their collective influence on diet quality. This trial was registered at https://www.isrctn.com/ as ISRCTN89898870.

Does Responsiveness to Basic Tastes Influence Preadolescents' Food Liking? Investigating Taste Responsiveness Segment on Bitter-Sour-Sweet and Salty-Umami Model Food Samples

The objective of this study was to investigate the relationships between taste responsiveness and food liking in preadolescents. Model food samples of grapefruit juice (GF) and vegetable broth (VB) modified with four additions of sucrose and sodium chloride, respectively, were employed. Intensity perception for sweetness, sourness, and bitterness were measured in GF while saltiness and umami were measured in VB. The children (N = 148) also completed food choice, familiarity, stated liking and neophobia questionnaires. The test was conducted at school, with instructions provided remotely via video call. Four segments were defined differing in basic taste responsiveness. Segments and sucrose concentrations significantly affected liking for GF, while no significant effect of segments and sodium chloride concentrations occurred on liking for VB. An increasing sucrose concentration was positively associated with liking for GF only in the segment with low responsiveness to bitter and sour tastes. No significant differences across segments were found for food choice, familiarity, stated liking, and neophobia. Conclusively, relationships between taste responsiveness and liking are product and basic taste-dependent in addition to being subject-dependent. Strategies to improve acceptance by using sucrose as a suppressor for warning sensations of bitterness and sourness can be more or less effective depending on individual responsiveness to the basic tastes.

The prevalence of constipation and its relation to sweet taste preference among patients receiving methadone maintenance treatment

BACKGROUND

Preference for sweet-tasting foods, weight gain, and constipation characterize patients receiving methadone maintenance treatment (MMT). The prevalence of constipation in MMT and its relation to preference for sweet taste and body mass index (BMI) are undetermined.

METHODS

A random sample of 83 patients was interviewed for constipation with the Patient Assessment Constipation Quality of Life (PAC-QOL) questionnaire. They rated taste intensity and reward of sweet, salty, and sour solutions by means of a nine-point Likert scale. Data on their BMI, drugs in urine, methadone dose, and serum levels were analyzed.

RESULTS

Forty-two patients reported minimum to severe constipation. They characterized as having longer durations of opioid usage before MMT and worse sleep quality than non-constipated patients (logistic regression). Constipation intensity was inversely correlated with duration in MMT and linearly correlated with the Patient Assessment Constipation Quality of Life score. Patients with constipation rated reward to sweet taste significantly higher with no differences in taste intensity compared to non-constipated patients. Patients with high methadone serum levels (≥750 ng/mL) rated taste intensity significantly lower compared to those with normal methadone serum levels (<750 ng/mL), and the lowest rates were reported among patients with no constipation and high methadone serum levels.

CONCLUSIONS

Constipation was highly prevalent among MMT patients and associated with poor sleep and lower quality of life. The relation to preference for sweets, as reflected by higher reward rating, strongly supports the need for nutritional intervention to alleviate constipation symptoms and improve quality of life and sleep.

Impact of Very Hot Drink Consumption Habits, Age, and Sex, on Taste Sensitivity

The temperature range for consuming hot drinks includes temperatures that can damage cells on the tongue. We hypothesized that the consumption of very hot drinks can lead to a decrease in the ability to perceive low concentrations of tastants. We evaluated the ability to perceive low concentrations of five prototypical sapid compounds in 42 women and 40 men aged 18-65. A questionnaire made it possible to collect the usual frequencies (number of unit/day) and consumption temperature levels (medium hot/very hot) for four very common hot drinks (coffee, tea, herbal infusions, and hot chocolate). Our results showed that subjects who consumed very hot drinks (versus medium hot) were less sensitive to sweet (p = 0.020) and salty (p = 0.046) tastes. An aggravating effect of high consumption frequencies was only shown for sweet taste (p = 0.036). Moreover, our data also showed that women were more sensitive than men to sour, bitter, and umami tastes (p values < 0.05), as well as that taste sensitivity decreases with age, especially after 50 years old (all tastes; p values < 0.05). These findings strengthen our knowledge about the influence of sex and age on taste sensitivity, and they provide knowledge on the influence of consumption habits related to hot drinks on taste sensitivity.

Mechanisms of umami taste perception: From molecular level to brain imaging

Due to unique characteristics, umami substances have gained much attention in the food industry during the past decade as potential replacers to sodium or fat to increase food palatability. Umami is not only known to increase appetite, but also to increase satiety, and hence could be used to control food intake. Therefore, it is important to understand the mechanism(s) involved in umami taste perception. This review discusses current knowledge of the mechanism(s) of umami perception from receptor level to human brain imaging. New findings regarding the molecular mechanisms for detecting umami tastes and their pathway(s), and the peripheral and central coding to umami taste are reviewed. The representation of umami in the human brain and the individual variation in detecting umami taste and associations with genotype are discussed. The presence of umami taste receptors in the gastrointestinal tract, and the interactions between the brain and gut are highlighted. The review concludes that more research is required into umami taste perception to include not only oral umami taste perception, but also the wider "whole body" signaling mechanisms, to explore the interaction between the brain and gut in response to umami perception and ingestion.

Comparing the taste-modifying properties of nanocellulose and carboxymethyl cellulose

The taste-modifying properties of nanofibrillar cellulose (NFC) and carboxymethyl cellulose (CMC) are compared for the first time. The samples were prepared in the form of gels, with and without added sweet and bitter taste components. As viscosity itself is known to affect taste perception, the viscosities of NFC and CMC samples were set to the same level as shear rates commonly found in the oral cavity. A trained panel of 10 assessors evaluated the bitterness and sweetness of the samples. Further, the assessors were given an opportunity to describe the samples in free words. The taste-modifying capacities of the thickening agents were at the same level when sweet compounds were added. However, CMC was better able to reduce the bitterness of quinine hydrochloride than NFC, which did not show any bitterness-reduction ability with the compound. This was unexpected, as our previous studies of NFC showed fairly high binding capacity with quinine. The open-ended responses revealed that the NFC-containing samples had an astringent sensation, while certain assessors observed a sensation of saltiness in the CMC samples. This may explain the inability of NFC to mask the bitterness of quinine hydrochloride, as astringency may act as a bitterness enhancer, while saltiness may suppress it. Both thickening agents were perceived as slightly bitter. Our study reveals the need for further assessment of the orosensory properties of NFC, particularly the magnitude and origin of its astringency, before it can be fully utilized in food industry applications.

Taste Interactions between Sweetness of Sucrose and Sourness of Citric and Tartaric Acid among Chinese and Danish Consumers

Tastes interact in almost every consumed food or beverage, yet many aspects of interactions, such as sweet-sour interactions, are not well understood. This study investigated the interaction between sweetness from sucrose and sourness from citric and tartaric acid, respectively. A cross-cultural consumer study was conducted in China (n = 120) and Denmark (n = 139), respectively. Participants evaluated six aqueous samples with no addition (control), sucrose, citric acid, tartaric acid, or a mixture of sucrose and citric acid or sucrose and tartaric acid. No significant difference was found between citric acid and tartaric acid in the suppression of sweetness intensity ratings of sucrose. Further, sucrose suppressed sourness intensity ratings of citric acid and tartaric acid similarly. Culture did not impact the suppression of sweetness intensity ratings of citric or tartaric acid, whereas it did influence sourness intensity ratings. While the Danish consumers showed similar suppression of sourness by both acids, the Chinese consumers were more susceptible towards the sourness suppression caused by sucrose in the tartaric acid-sucrose mixture compared to the citric acid-sucrose mixture. Agglomerative hierarchical cluster analysis revealed clusters of consumers with significant differences in sweetness intensity ratings and sourness intensity ratings. These results indicate that individual differences in taste perception might affect perception of sweet-sour taste interactions, at least in aqueous solutions.

Food Consumption and Emotions at a Salad Lunch Buffet in a Multisensory Environment

The food experience is multisensory and multisensory external stimuli may affect food choice and emotions. The objective of this study was to evaluate the effect of a multisensory eating environment on food choice, intake and the emotional states of the subjects in a salad lunch buffet setting. A total of 30 female subjects consumed a salad lunch twice in the multisensory laboratory. The two test conditions (control and multisensory condition with environmental stimuli) were randomized and the visits were scheduled one week apart. Subjects selected and ate a meal from a salad buffet including 14 food items and the intake of each item was weighed. They answered an online questionnaire about the meal and their emotional states (20 different emotion terms) after the lunch. There was no significant difference in the food consumption between the control and multisensory conditions. The subjects were very satisfied with their lunch for both study visits but the pleasantness of the eating environment was rated higher under the multisensory condition. In emotional terms, the subjects selected the term "happy" significantly more frequently under the multisensory condition compared with the control. In conclusion, the multisensory eating environment in this study was not related to food intake but may be associated with positive emotions. The effect of the eating environment on food choice and experience deserves further study with a larger study population in a real lunch restaurant setting.

Almli V. Investigating the Relationships between Basic Tastes Sensitivities, Fattiness Sensitivity, and Food Liking in 11-Year-Old Children

This study investigates the relationships between basic tastes and fattiness sensitivity and food liking in 11-year-old children. The basic taste sensitivity of 106 children was measured using different methods, namely detection (DT) and recognition (RT) thresholds, and taste responsiveness. Caffeine and quinine (bitter), sucrose (sweet), citric acid (sour), sodium chloride (salty), and monosodium glutamate (umami) were investigated for DT and RT at five concentrations in water solutions. In addition, taste responsiveness and liking were collected for the high-intensity concentrations. PROP (6-n-propylthiouracil) responsiveness was tested on paper strips. Fattiness sensitivity was measured by a paired comparison method using milk samples with varying fat content. Liking for 30 food items was recorded using a food-list questionnaire. The test was completed in a gamified “taste detective” approach. The results show that DT correlates with RT for all tastes while responsiveness to PROP correlates with overall taste responsiveness. Caffeine and quinine differ in bitterness responsiveness and liking. Girls have significantly lower DTs than boys for bitterness and sweetness. Food liking is driven by taste and fattiness properties, while fatty food liking is significantly influenced by fattiness sensitivity. These results contribute to a better holistic understanding of taste and fattiness sensitivity in connection to food liking in preadolescents.

Factors related to sensory properties and consumer acceptance of vegetables

Many consumers perceive the bitter taste or other sensory characteristic of vegetables as unpleasant, posing a challenge to dietary recommendations aiming to increase vegetable consumption. Food experience is multisensory, with complex interactions between the senses and individual differences in sensory perception. This review focuses on the factors affecting sensory properties of vegetables and sensory perception of vegetables among adults. Topical examples of sensory quality and evaluation of vegetable samples are presented. Cultivar and growing conditions are related to the internal sensory quality of vegetables. The effects of different processing methods, such as freezing and cooking, on the sensory properties of vegetables are also reviewed. Flavor modification of vegetables with seasonings may be used to improve palatability and incorporating vegetables to meals may increase the intake of vegetables. Recently, external factors (e.g. visual and odor stimuli) have been tested in multisensory research in the context of vegetable perception and choice. These options to achieve better sensory quality, more palatable meals and pleasant eating context may be used to promote vegetable intake among adults.

Taste Sensitivity Is Associated with Food Consumption Behavior but not with Recalled Pleasantness

As taste perception varies between individuals, it might be important in explaining food consumption behavior. Previous studies have focused on sensitivity to the bitter tastant PROP (6-n-propylthiouracil) concerning eating with little attention paid to other tastants. For the first time, connections between food consumption behavior, pleasantness, and taste sensitivity are studied with five taste modalities. Sensitivity to bitterness, sourness, umami, saltiness, and sweetness as well as an overall taste sensitivity score was determined with intensity evaluation for 199 Finnish adults. Recalled pleasantness and food consumption behavior were enquired with online questionnaires. Consumption concerned intake of vegetables, fruits, and berries; use-frequency of specific foods; and tendency to mask or modify tastes of foods. All modality-specific taste sensitivities were related to some consumption behavior but none to recalled pleasantness. A higher taste sensitivity score indicated avoidance of coffee, lower consumption of pungent foods, and a more frequent habit of adding ketchup to a meal. In conclusion, it may be more informative to study the influence of taste sensitivity on food consumption behavior with taste modalities separately rather than with a general indicator of taste sensitivity. Additionally, these results highlight the importance of studying actual behavior toward food and not just liking.

Individual Variation in PROP Status, Fungiform Papillae Density, and Responsiveness to Taste Stimuli in a Large Population Sample

Despite considerable research investigating the role of 6-n-propylthiouracil bitterness perception and variation of fungiform papillae density in food perception, this relationship remains controversial as well as the association between the 2 phenotypes. Data from 1119 subjects (38.6% male; 18-60 years) enrolled in the Italian Taste project were analyzed. Responsiveness to the bitterness of 6-n-propylthiouracil was assessed on the general Labeled Magnitude Scale. Fungiform papillae density was determined from manual counting on digital images of the tongue. Solutions of tastes, astringent, and pungent sensations were prepared to be moderate/strong on a general Labeled Magnitude Scale. Four foods had tastants added to produce 4 variations in target sensations from weak to strong (pear juice: citric acid, sourness; chocolate pudding: sucrose, sweetness; bean purée: sodium chloride, saltiness; and tomato juice: capsaicin, pungency). Women gave ratings to 6-n-propylthiouracil and showed fungiform papillae density that was significantly higher than men. Both phenotype markers significantly decreased with age. No significant correlations were found between 6-n-propylthiouracil ratings and fungiform papillae density. Fungiform papillae density variation does not affect perceived intensity of solutions. Responsiveness to 6-n-propylthiouracil positively correlated to perceived intensity of most stimuli in solution. A significant effect of fungiform papillae density on perceived intensity of target sensation in foods was found in a few cases. Responsiveness to 6-n-propylthiouracil positively affected all taste intensities in subjects with low fungiform papillae density whereas there were no significant effects of 6-n-propylthiouracil in those with high fungiform papillae density. These data highlight a complex interplay between 6-n-propylthiouracil status and fungiform papillae density and the need of a critical reconsideration of their role in food perception and acceptability.

Individual Differences in the Perception of Color Solutions

The color of food is important for flavor perception and food selection. The aim of the present study was to evaluate the visual color perception of liquid samples among Finnish adult consumers by their background variables. Participants (n = 205) ranked six different colored solutions just by looking according to four attributes: from most to least pleasant, healthy, sweet and sour. The color sample rated most frequently as the most pleasant was red (37%), the most healthy white (57%), the most sweet red and orange (34% both) and the most sour yellow (54%). Ratings of certain colors differed between gender, age, body mass index (BMI) and education groups. Females regarded the red color as the sweetest more often than males (p = 0.013) while overweight subjects rated the orange as the sweetest more often than normal weight subjects (p = 0.029). Personal characteristics may be associated with some differences in color associations.