Exploring the effects of genotypical and phenotypical variations in bitter taste sensitivity on perception,liking and intake of brassica vegetables in the UK

Brassicaceous vegetables (BV) have chemoprotective effects and yet consumption of BV in the UK is low. Previous studies suggest perception, liking and intake of BV are influenced by bitter taste sensitivity which this study further explores. Phenotypical taste sensitivity of 136 subjects was classified using propythiouracil (PROP) and sodium chloride and fungiform papillae density (FPD) was measured from tongue images. Polymorphisms of TAS2R38 and gustin (CA6) genes were analysed. Liking and bitterness of four raw vegetables (two BV (broccoli and white cabbage) and two non-BV (spinach and courgette)), as well as habitual consumption, were evaluated.There was a significant association between TAS2R38 genotype and PROP taster status (p < 0.0001) and between FPD and PROP taster status (p = 0.029). Individuals with greater sensitivity for PROP predominantly had TAS2R38 PAV/PAV genotype and greater FPD. BV were perceived as more bitter than non-BV (p < 0.0001) with PAV/PAV subjects perceiving significantly stronger bitter intensity. There was a significant difference in liking for the four vegetables (p = 0.002), and between consumers of different TAS2R38 genotype (p = 0.0024). Individuals with TAS2R38 AVI/AVI genotype liked BV more. Regarding intake, both PAV/PAV and AVI/AVI individuals consumed more total vegetables and BV than PAV/AVI. Although PROP nontasters tended to consume more vegetables and BV than the other two phenotype groups, liking and vegetable intake were not significantly affected by taste phenotype. Although there was not a significant effect of CA6 genotype on bitterness ratings, there was a significant interaction between CA6 and TAS2R38, and in addition CA6 genotype was significantly associated with BV intake. However, these effects require validation as the proportions of the population with the CA6 G/G genotype was extremely small (7%).Our results confirmed that bitter taste perception in vegetables was influenced by both genotype and phenotype of bitter taste sensitivity. Moreover, our findings demonstrated that neither genotype nor phenotype of taste sensitivity alone accurately predict vegetable liking and intake as demographic factors were found to have a substantial influence.     

Molecular insights into human taste perception and umami tastants: A review

Understanding taste is key for optimizing the palatability of seaweeds and other non-animal-based foods rich in protein. The lingual papillae in the mouth hold taste buds with taste receptors for the five gustatory taste qualities. Each taste bud contains three distinct cell types, of which Type II cells carry various G protein-coupled receptors that can detect sweet, bitter, or umami tastants, while type III cells detect sour, and likely salty stimuli. Upon ligand binding, receptor-linked intracellular heterotrimeric G proteins initiate a cascade of downstream events which activate the afferent nerve fibers for taste perception in the brain. The taste of amino acids depends on the hydrophobicity, size, charge, isoelectric point, chirality of the alpha carbon, and the functional groups on their side chains. The principal umami ingredient monosodium l -glutamate, broadly known as MSG, loses umami taste upon acetylation, esterification, or methylation, but is able to form flat configurations that bind well to the umami taste receptor. Ribonucleotides such as guanosine monophosphate and inosine monophosphate strongly enhance umami taste when l -glutamate is present. Ribonucleotides bind to the outer section of the venus flytrap domain of the receptor dimer and stabilize the closed conformation. Concentrations of glutamate, aspartate, arginate, and other compounds in food products may enhance saltiness and overall flavor. Umami ingredients may help to reduce the consumption of salts and fats in the general population and increase food consumption in the elderly.     

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.     

Consumption of lingonberries by TAS2R38 genotype and sensory quality of texture-designed lingonberry samples

Bitter taste receptor genotypes may be associated with the perception of bitterness in berries, and different processing methods may be used to modify the flavor of berry products. The aims of the present study were to investigate the consumption frequency of lingonberries among TAS2R38 genotyped subjects (n = 83) and to evaluate the sensory characteristics of different texture-modified lingonberry samples (subjects n = 12, samples n = 8). Reported intake of lingonberries varied with TAS2R38 genotype, with more bitter sensitive individuals consuming them less frequently. The flavor profile of lingonberries was modifiable by food structure. In particular, foam and/or emulsion structures decreased the perceived intensity of bitterness, astringency and sourness of lingonberry samples. Sweetness was significantly higher in heavy foamed jelly and foamed emulsion compared to pulp or foamed juice. In conclusion, new flavor and texture modification options should be investigated to increase the palatability and consumption of bitter tasting foods.     

The glucosinolates sinigrin and progoitrin are important determinants for taste preference and bitterness of Brussels sprouts

The glucosinolates, sinigrin and progoitrin, are related to the bitterness observed in Brussels sprouts. The role of these glucosinolates in taste preference for Brussels sprouts (Brassica oleracea var gemmifera) was studied with two different consumer taste panels and an analytical panel. Four different taste trials were conducted between 1989 and 1995 to study the role of sinigrin and progoitrin on taste preference and bitterness of sprouts. Sinigrin and progoitrin correlated negatively with taste preference of sprouts when their combined content was higher than 2·2 g kg⁻¹. Under these conditions the overall preference for different Brussels sprouts cultivars, in two different trial designs, was accounted for, respectively, 64 (Novartis Seeds BV) and 86% (TNO) by the contents of the glucosinolates sinigrin and progoitrin. In two additional trials, in which the combined content of sinigrin and progoitrin of all cultivars was below 2·2 g kg⁻¹, no relationship between taste preference and the content of both glucosinolates was observed. In the latter trials the content of sinigrin and progoitrin was found to be correlated with bitterness (r²_multiple = 0·67 and 0·93, respectively) as assessed by an analytical panel. The results of the taste trials show that both bitterness and taste preference for sprouts are correlated with the content of sinigrin and progoitrin. Taste preference for sprouts is only correlated with sinigrin and progoitrin when their combined content exceeds 2·2 g kg⁻¹, while bitterness is correlated with both glucosinolates for the whole studied content range. © 1998 Society of Chemical Industry.     

Natural antioxidants and antioxidant capacity of Brassica vegetables: A review

Dietary antioxidants, such as water-soluble vitamin C and phenolic compounds, as well as lipid-soluble vitamin E and carotenoids, present in vegetables contribute both to the first and second defense lines against oxidative stress. As a result, they protect cells against oxidative damage, and may therefore prevent chronic diseases, such as cancer, cardiovascular disease, and diabetes. Brassica vegetables, which include different genus of cabbage, broccoli, cauliflower, Brussels sprouts, and kale, are consumed all over the world. This review focuses on the content, composition, and antioxidant capacity both lipid- and water-soluble antioxidants in raw Brassica vegetables. The effects of post-harvest storage, industrial processing, and different cooking methods on stability of bioactive components and antioxidant activity also are discussed.     

Genetic and environmental influences on liking and reported intakes of vegetables in Irish children

Variation in the bitterness of 6-n-propylthiouracil (PROP) is partially explained by polymorphisms in the TAS2R38 gene. Based on their perception of bitterness from PROP, people may be classified into non-, medium and supertasters. PROP perception has previously been linked to liking for cruciferous vegetables in children in some studies, but only one study to date has examined TAS2R38 genotype and its relationship with vegetable intake in children. Children’s vegetable consumption generally does not meet the recommended guidelines, thus the present study aimed to examine the influence of oral sensory measures, genetic variation and social factors on vegetable liking and intake. Vegetable liking in 7–13 year old Irish children (n = 525) was measured on a 5-point liking scale, and dietary intakes were assessed via a 3-day diet history. Vegetable intakes were calculated and standardised per kg body weight. A subset of children (n = 485) were genotyped for SNPs in TAS2R38, (A49P, V262A, I296V), and fungiform papilla (FP) were counted. The bitterness of PROP and sweetness of sucrose were rated on a generalised labelled magnitude scale (gLMS). PROP and sucrose intensity were significantly correlated (R² = 0.33, p = 0.001), although neither sucrose intensity nor FP density differed across the TAS2R38 genotype groups. Supertasters were less likely than nontasters to have tried/tasted cruciferous vegetables p < 0.04). A small, positive correlation was seen in FP density and vegetable intake, but only in the AVI homozygous children, (R² = 0.17, p = 0.035). 174 Nutrient acceptable children reported an intake of one or more of the vegetables of interest in the 3-day period. Liking of cruciferous vegetables and reported intake were significantly correlated. In multiple regression analyses in this subsection of the cohort, socioeconomic status (SES) and gender were more important than PROP bitterness or TAS2R38 genotype in predicting intakes (approximately 15% of liking and 67% of intake was explained by these models). Overall, neither PROP taster status nor TAS2R38 genotype alone had significant impact on bitter vegetable liking or intake. Further research into FP density and vegetable liking and intake may be warranted.     

Variation in the content of glucosinolates,hydroxycinnamic acids,carotenoids, total antioxidant capacity and low‐molecular‐weight carbohydrates in Brassica vegetables

Bioactive compounds were investigated in genotypes (cauliflower 10, white cabbage 10, curly kale 1) and plant parts of the three crops. The content of most of the major glucosinolates glucobrassicin, sinigrin and glucoiberin differed significantly between cultivars. Samples harvested in 2000 had higher amounts of several glucosinolates than samples from 1999. Within cauliflower the buds of the floret had 1.5 to 2.5‐fold higher concentration of glucobrassicin and 4‐methoxyglucobrassicin than the stalk. In white cabbage several glucosinolates had their highest content in the outer leaves (up to 2‐fold higher). Upper leaves of curly kale contained 5‐fold more of total glucosinolates than lower leaves. Chlorogenic acid was the dominating hydroxycinnamate in curly kale, which also contained at least ten times more of carotenoids (mainly lutein) than white cabbage. Total antioxidant capacity (TAC) assayed with the FRAP method was 0.76 (0.06) µmol/g fw (mean (SD)) in water‐soluble and 0.32 (0.04) in water‐insoluble extracts of cauliflower which was 62–68% higher than in white cabbage. Curly kale contained 6.4 and 6.1 µmol/g fw TAC in water‐soluble and water‐insoluble extracts. TAC did not differ between plant parts. Progoitrin and 4‐hydroxyglucobrassicin were correlated to water‐soluble TAC in white cabbage, probably reflecting a variation in other compounds. Cauliflower contained less glucose, fructose and sorbitol but more sucrose than white cabbage. Curly kale had lower contents of glucose (～2 times), fructose (～4–5 times) and sucrose (20 and 36 times, respectively) than cauliflower and white cabbage, while inositol was only found in curly kale. Storage of white cabbage reduced the amount of sorbitol and sucrose. The study shows that cultivar, plant part and storage affect the content of bioactive compounds in Brassica vegetables. The variation between years, as in cauliflower, is due to environmental factors. Since the cultivar ranking order was rather stable for several components the data could provide a basis for the selection of cultivars optimised for valuable health components for fresh market consumption. Copyright © 2005 Society of Chemical Industry     

The role of taste in alcohol preference,consumption and risk behavior

Alcohol consumption is widespread, and high levels of use are associated with increased risk of developing an alcohol use disorder. Thus, understanding the factors that influence alcohol intake is important for disease prevention and management. Additionally, elucidating the factors that associate with alcohol preference and intake in non-clinical populations allows for product development and optimisation opportunities for the alcoholic beverage industry. The literature on how taste (orosensation) influences alcohol behavior is critically appraised in this review. Ethanol, the compound common to all alcoholic beverages, is generally aversive as it primarily elicits bitterness and irritation when ingested. Individuals who experience orosensations (both taste and chemesthetic) more intensely tend to report lower liking and consumption of alcoholic beverages. Additionally, a preference for sweetness is likely associated with a paternal history of alcohol use disorders. However, conflicting findings in the literature are common and may be partially attributable to differences in the methods used to access orosensory responsiveness and taste phenotypes. We conclude that while taste is a key driver in alcohol preference, intake and use disorder, no single taste-related factor can adequately predict alcohol behaviour. Areas for further research and suggestions for improved methodological and analytical approaches are highlighted.     

A comparative study on the polyphenolic content,antibacterial activity and antioxidant capacity of different solvent extracts of Brassica oleracea vegetables

Brassica vegetables are rich in polyphenols, flavonoids and glucosinolates. Investigation was undertaken to optimise the best solvents among 60% ethanol, acetone and methanol for the extraction of polyphenols from Brassica vegetables. Furthermore, different properties such as antibacterial activity and antioxidant capacity were also investigated. Results showed that a 60% methanolic extract showed the highest total phenolic content which was 23.6, 20.4 and 18.7 mg gallic acid equivalents (GAE) g^?1 extract for broccoli, Brussels sprouts and white cabbage, respectively. The hydroxybenzoic acid content of various solvent extracts ranged from 5.86 to 8.91 GAE g^?1 extract for broccoli, 2.70 to 5.44 GAE g^?1 extract for Brussels sprouts and 3.69 to 4.86 GAE g^?1 extract for white cabbage, while the hydroxycinnamic acid content ranged from 0.78 to 1.26 chlorogenic acid equivalents (CAE) g^?1 extract for broccoli, 1.41 to 3.45 CAE g^?1 extract for Brussels sprouts and 0.49 to 1.14 CAE g^?1 extract for white cabbage. A concentration‐dependent antioxidative capacity was confirmed for different reactive oxygen species, and moderate antibacterial activity was observed against a number of Gram‐negative and Gram‐positive food spoilage and food pathogenic bacteria. Solvents significantly affected polyphenolic content and its different properties, and the methanol was found to be the best solvent for the extraction of polyphenols from studied Brassica vegetables.     

A review of the associations between single nucleotide polymorphisms in taste receptors,eating behaviors,and health

Food preferences and dietary habits are heavily influenced by taste perception. There is growing interest in characterizing taste preferences based on genetic variation. Genetic differences in the ability to perceive key tastes may impact eating behavior and nutritional intake. Therefore, increased understanding of taste biology and genetics may lead to new personalized strategies, which may prevent or influence the trajectory of chronic disease risk. Recent advances show that single nucleotide polymorphisms (SNPs) in the CD36 fat taste receptor are linked to differences in fat perception, fat preference, and chronic-disease biomarkers. Genetic variation in the sweet taste receptor T1R2 has been shown to alter sweet taste preferences, eating behaviors, and risk of dental caries. Polymorphisms in the bitter taste receptor T2R38 have been shown to influence taste for brassica vegetables. Individuals that intensely taste the bitterness of brassica vegetables (“supertasters”) may avoid vegetable consumption and compensate by increasing their consumption of sweet and fatty foods, which may increase risk for chronic disease. Emerging evidence also suggests that the role of genetics in taste perception may be more impactful in children due to the lack of cultural influence compared to adults. This review examines the current knowledge of SNPs in taste receptors associated with fat, sweet, bitter, umami, and salt taste modalities and their contributions to food preferences, and chronic disease. Overall, these SNPs demonstrate the potential to influence food preferences and consequently health.     

The black agonist-receptor model of high potency sweeteners, and its implication to sweetness taste and sweetener design

The dose responses of the most commonly used high potency sweeteners (HPSs) have been measured by a more precise sensory procedure. The data were analyzed by Black's pharmacological model that takes into account not only agonist binding affinity but transduction efficiency as well. HPSs are clearly segregated into 2 groups depending on whether they bind to T1R2 or T1R3 of the receptor heterodimer. Surprisingly, the more potent sweeteners have lower transduction efficiencies. The implications of these on consumer product development and HPS design are discussed.     

The use of immersive technologies to improve consumer testing: The role of ecological validity,context and engagement in evaluating coffee

Traditionally, sensory consumer testing is completed in isolated sensory booths where the influence of non-product (e.g., environmental) attributes is controlled. However, these highly controlled environments strip away meaningful contextual (visual, auditory and olfactory) information important in forming consumer perceptions, liking and behaviors. Moreover, boredom and lack of panelist engagement associated with typical testing paradigms can result in uninformative or misleading consumer data. We utilized an immersive environment depicting a virtual coffeehouse, replete with visual, auditory and olfactory cues found regularly in this setting, and compared liking scores for five coffees to those obtained from the same individuals in a traditional testing environment in which contextual information was absent. We found significant differences in preference order and liking for coffees evaluated by the same people in the two settings and showed hedonic data collected in the virtual coffeehouse to be more discriminating and a more reliable predictor of future coffee liking unlike data collected in traditional sensory booths. Additionally, we found consumers to be more engaged in the testing when evaluating coffees in the virtual coffeehouse, an outcome that likely also contributed to improved data quality. These results suggest that during product evaluations, extrinsic contextual information is processed simultaneously with the intrinsic product attributes to influence hedonic assessments and shape reward outcomes. Further, these results suggest that methodological changes to current testing strategies have the potential to improve the reliability of consumer data providing food and consumer product companies significant savings on product development costs and failed launches.     

Correlates of food choice in unemployed young people: The role of demographic factors,self-efficacy,food involvement,food poverty and physical activity

Associations between socio-demographic and psychological factors and food choice patterns were explored in unemployed young people who constitute a vulnerable group at risk of poor dietary health. Volunteers (N = 168), male (n = 97) and female (n = 71), aged 15–25 years were recruited through United Kingdom (UK) community-based organisations serving young people not in education training or employment (NEET). Survey questionnaire enquired on food poverty, physical activity and measured responses to the Food Involvement Scale (FIS), Food Self-Efficacy Scale (FSS) and a 19-item Food Frequency Questionnaire (FFQ). A path analysis was undertaken to explore associations between age, gender, food poverty, age at leaving school, food self-efficacy (FS-E), food involvement (FI) (kitchen; uninvolved; enjoyment), physical activity and the four food choice patterns (junk food; healthy; fast food; high fat). FS-E was strong in the model and increased with age. FS-E was positively associated with more frequent choice of healthy food and less frequent junk or high fat food (having controlled for age, gender and age at leaving school). FI (kitchen and enjoyment) increased with age. Higher FI (kitchen) was associated with less frequent junk food and fast food choice. Being uninvolved with food was associated with more frequent fast food choice. Those who left school after the age of 16 years reported more frequent physical activity. Of the indirect effects, younger individuals had lower FI (kitchen) which led to frequent junk and fast food choice. Females who were older had higher FI (enjoyment) which led to less frequent fast food choice. Those who had left school before the age of 16 had low food involvement (uninvolved) which led to frequent junk food choice. Multiple indices implied that data were a good fit to the model which indicated a need to enhance food self-efficacy and encourage food involvement in order to improve dietary health among these disadvantaged young people.     

Extending the theory of planned behavior to understand consumer purchase behavior for organic vegetables in Brazil: The role of perceived health benefits,perceived sustainability benefits and perceived price

This study explores the factors that influence consumer purchase intention and behavior for organic vegetables in Brazil. A conceptual model based on the theory of planned behavior (TPB) was developed. In addition to all standard relationships in the TPB, the candidate variables of perceived health benefits, perceived sustainability benefits, and perceived price were added to the TPB-based model. Attitude was expected to mediate the relation between perceived health benefits and intention and the relation between perceived sustainability benefits and intention. Perceived price was expected to moderate the relation between intention and behavior. An online survey was conducted, resulting in a sample size of 504 participants. Data were analyzed by partial-least squares structural equation modeling. The results indicate that intention and perceived behavioral control influence the purchase behavior for organic vegetables, with intention presenting the strongest impact on behavior. Attitude has the strongest impact on consumer intention to purchase organic vegetables, followed by perceived behavioral control and subjective norms. The results also indicate that attitude mediates the relations between perceived health benefits and intention and perceived sustainability benefits and intention. Perceived price moderates the relationship between intention and behavior. Based on the results, managerial implications are presented.