Macronutrient Sensing in the Oral Cavity and Gastrointestinal Tract: Alimentary Tastes.

There are numerous and diverse factors enabling the overconsumption of foods, with the sense of taste being one of these factors. There are four well established basic tastes: sweet, sour, salty, and bitter; all with perceptual independence, salience, and hedonic responses to encourage or discourage consumption. More recently, additional tastes have been added to the basic taste list including umami and fat, but they lack the perceptual independence and salience of the basics. There is also emerging evidence of taste responses to kokumi and carbohydrate. One interesting aspect is the link with the new and emerging tastes to macronutrients, with each macronutrient having two distinct perceptual qualities that, perhaps in combination, provide a holistic perception for each macronutrient: fat has fat taste and mouthfeel; protein has umami and kokumi; carbohydrate has sweet and carbohydrate tastes. These new tastes can be sensed in the oral cavity, but they have more influence post- than pre-ingestion. Umami, fat, kokumi, and carbohydrate tastes have been suggested as an independent category named alimentary. This narrative review will present and discuss evidence for macronutrient sensing throughout the alimentary canal and evidence of how each of the alimentary tastes may influence the consumption of foods.

Quantitative Comparative Integrated Proteomic and Phosphoproteomic Analysis of Chicken Egg Yolk Proteins under Diverse Storage Temperatures.

To investigate the alterations of egg yolk protein abundances and their phosphorylation status at different storage temperatures, a comparative quantitative study of unfertilized chicken egg yolk after 15 days of storage at 4 and 37 °C was performed. Altogether, 445 proteins were identified in our study, of which the abundances of 154 proteins were significantly changed when comparing high-temperature storage with low-temperature storage, including 42 up-regulated and 112 down-regulated proteins. In the phosphoproteome, we identified a total of 137 phosphorylated sites on 326 peptides corresponding to 51 proteins. The results showed that the degree of phosphorylation for most egg yolk proteins was enhanced during high-temperature storage. Furthermore, GO analysis indicated that these phosphoproteins of egg yolk may be closely related to the binding, catalysis, and transport functions. The results provide further insights into the effect of storage temperature on egg proteome changes and their phosphorylation level. Moreover, this study can provide a theoretical basis for the improvement of egg quality during storage by phosphorylation modification in the food industry.

A low-fat diet up-regulates expression of fatty acid taste receptor gene FFAR4 in fungiform papillae in humans: a co-twin randomised controlled trial.

Fatty acid taste (FAT) perception is involved in the regulation of dietary fat intake, where impaired FAT is associated with increased fatty food intake. There are a number of FAT receptors identified on human taste cells that are potentially responsible for FAT perception. Manipulating dietary fat intake, and in turn FAT perception, would elucidate the receptors that are associated with long-term regulation of FAT perception. The present study aimed to assess associations between diet-mediated changes to FAT receptors and FAT perception in humans. A co-twin randomised controlled trial was conducted, where each matching twin within a pair were randomly allocated to either an 8-week low-fat (LF; <20 % energy fat) or an 8-week high-fat (HF; >35 % energy fat) diet. At baseline and week 8, fungiform papillae were biopsied in the fasted state and FAT receptor gene expressions (cluster of differentiation 36 (CD36), free fatty acid receptor 2 (FFAR2), FFAR4, G protein-coupled receptor 84 (GPR84) and a delayed rectifying K+ channel (K+ voltage-gated channel subfamily A member 2; KCNA2)) were measured using RT-PCR; and FAT threshold (FATT) was assessed using three-alternate forced choice methodology. Linear mixed models were fitted, adjusting for correlation between co-twins. Intake was compliant with the study design, with the LF and HF groups consuming 14·8 and 39·9 % energy from fat, respectively. Expression of FFAR4 increased by 38 % in the LF group (P = 0·023; time-diet interaction P = 0·063). ΔFFAR4 (Δ, week 8-baseline) was associated with Δfat intake (g) ( = -159·4; P < 0·001) and ΔFATT ( = -8·8; P = 0·016). In summary, FFAR4 is involved in long-term diet-mediated changes to FAT perception. Manipulating dietary fat intake, and therefore FFAR4 expression, might aid in reducing taste-mediated passive overconsumption of fatty foods.

The Response of More Health Focused and Less Health Focused People to a Physical Activity Calorie Equivalent Label on Discretionary Snack Foods.

A Physical Activity Calorie Equivalent (PACE) label shows the minutes of physical activity required to burn off the caloric content of a particular food. This study investigated the influence of PACE labelling on liking and consumption of discretionary snack foods in a group of more health focused and less health focused consumers. Participants (n = 97) tasted and rated (i.e., liking, prospective consumption) a range of snack foods with or without a PACE label. Total sampling consumption was also measured. Participants completed a shortened version of the International Physical Activity Questionnaire and the General Health Interest Scale questionnaire. Paired samples t-test, independent samples t-tests, a General Linear Model and Chi-Square tests were used to check for statistical significance. For more health focused participants (n = 57), the PACE label decreased only liking (p = 0.02). The PACE label was not effective in reducing liking (p = 0.49), prospective consumption (defined as the amount of the sample participants thought that they could consume) (p = 0.10) or consumption (p = 0.41) of energy-dense discretionary snack foods for less health focused individuals (n = 40). The level of participants' physical activity did not facilitate the influence of PACE labelling on liking, consumption or prospective consumption. The PACE label was found to not be effective among less health focused individuals or the overall sample population. Therefore, the PACE label may not be an effective labelling strategy to reduce the liking or consumption of discretionary snack foods.

Physical activity-equivalent label reduces consumption of discretionary snack foods.

OBJECTIVE: The present research aimed to investigate the impact of the physical activity calorie equivalent (PACE) front-of-pack label on consumption, prospective consumption and liking of familiar and unfamiliar discretionary snack foods. DESIGN: In a within-subject randomised design, participants tasted and rated liking (9-point hedonic scale) and prospective consumption (9-point category scale) of four different snack foods with four different labels (i.e. blank, fake, PACE, PACE doubled) and four control snack foods. The twenty snack foods were presented during two 45 min sessions (i.e. ten snack foods per session) which were separated by one week. The amount participants sampled of each snack food was measured. SETTING: The study was conducted in the Centre for Advanced Sensory Sciences laboratory at Deakin University, Australia. SUBJECTS: The participants were 153 university students (126 females, twenty-seven males, mean age 24·3 (sd 4·9) years) currently enrolled in an undergraduate nutrition degree at Deakin University. RESULTS: When the PACE label was present on familiar snack foods, participants sampled 9·9 % (22·8 (sem 1·4) v. 25·3 (sem 1·5) g, P=0·03) less than when such label was not present. This was in line with a decreased prospective snack food consumption of 9·1 % (3·0 (sem 0·2) v. 3·3 (sem 0·2) servings, P=0·03). Such pattern was not seen in unfamiliar snacks. CONCLUSIONS: The PACE label appears to be a promising way to decrease familiar discretionary snack food consumption in young, health-minded participants.

Oil Perception-Detection Thresholds for Varying Fatty Stimuli and Inter-individual Differences.

Multiple lines of research have demonstrated that humans can perceive fat in the form of free fatty acids (FFAs). However, the dietary concentration of FFAs is generally very low and fat is mainly consumed as triacylglycerol (TAG). The aim of this study was to examine the perception of different fatty stimuli and possible associations between them. Therefore, detection thresholds for 4 fatty stimuli (oleic acid [FFA], paraffin oil [mixture of hydrocarbon molecules], canola oil [TAG-rich], and canola oil spiked with oleic acid [rich in TAGs and FFAs]) were determined in 30 healthy participants. Additionally, inter-individual differences in fat perception were examined. It was observed that oleic acid was perceivable at significantly lower concentrations than all other stimuli (P < 0.001). Similarly, canola oil with oleic acid was detectable at lower concentrations than canola oil alone (P < 0.001). Moreover, canola oil detection thresholds were significantly lower than paraffin oil detection thresholds (P = 0.017). Participants who were sensitive for low concentrations for oleic acid showed lower detection thresholds for canola oil with and without oleic acid, compared with participants that were less sensitive for oleic acid. The results of this study demonstrate that the higher the concentrations of FFAs in the stimuli, the lower the individual fat detection threshold. Moreover, participants being sensitive for lower concentrations of FFAs are also more likely to detect low concentrations of TAG-rich fats as it is found in the human diet.

A Comparison of Collection Techniques for Gene Expression Analysis of Human Oral Taste Tissue.

Variability in human taste perception is associated with both genetic and environmental factors. The influence of taste receptor expression on this variability is unknown, in part, due to the difficulty in obtaining human oral tissue that enables quantitative expression measures of taste genes. In a comparison of six current techniques (Oragene RNeasy Kit, Isohelix swab, Livibrush cytobrush, tongue saliva, cheek saliva collection, and fungiform papillae biopsy), we identify the fungiform papillae biopsy is the optimal sampling technique to analyse human taste gene expression. The fungiform papillae biopsy resulted in the highest RNA integrity, enabling amplification of all the assessed taste receptor genes (TAS1R1, TAS1R2, TAS1R3, SCNN1A and CD36) and taste tissue marker genes (NCAM1, GNAT3 and PLCß2). Furthermore, quantitative expression was observed in a subset of taste genes assessed from the saliva collection techniques (cheek saliva, tongue saliva and Oragene RNA kit). These saliva collection techniques may be useful as a non-invasive alternative sampling technique to the fungiform papillae biopsy. Identification of the fungiform papillae biopsy as the optimal collection method will facilitate further research into understanding the effect of gene expression on variability in human taste perception.

A prospective cohort study of the effects of adjuvant breast cancer chemotherapy on taste function, food liking, appetite and associated nutritional outcomes.

BACKGROUND: 'Taste' changes are commonly reported during chemotherapy. It is unclear to what extent this relates to actual changes in taste function or to changes in appetite and food liking and how these changes affect dietary intake and nutritional status. PATIENTS AND METHODS: This prospective, repeated measures cohort study recruited participants from three oncology clinics. Women (n = 52) prescribed adjuvant chemotherapy underwent standardised testing of taste perception, appetite and food liking at six time points to measure change from baseline. Associations between taste and hedonic changes and nutritional outcomes were examined. RESULTS: Taste function was significantly reduced early in chemotherapy cycles (p<0.05) but showed recovery by late in the cycle. Ability to correctly identify salty, sour and umami tastants was reduced. Liking of sweet food decreased early and mid-cycle (p<0.01) but not late cycle. Liking of savory food was not significantly affected. Appetite decreased early in the cycle (p<0.001). Reduced taste function was associated with lowest kilojoule intake (r = 0.31; p = 0.008) as was appetite loss with reduced kilojoule (r = 0.34; p = 0.002) and protein intake (r = 0.36; p = 0.001) early in the third chemotherapy cycle. Decreased appetite early in the third and final chemotherapy cycles was associated with a decline in BMI (p = <0.0005) over the study period. Resolution of taste function, food liking and appetite was observed 8 weeks after chemotherapy completion. There was no association between taste change and dry mouth, oral mucositis or nausea. CONCLUSION: The results reveal, for the first time, the cyclical yet transient effects of adjuvant chemotherapy on taste function and the link between taste and hedonic changes, dietary intake and nutritional outcomes. The results should be used to inform reliable pre-chemotherapy education.

Oleocanthal, a phenolic derived from virgin olive oil: a review of the beneficial effects on inflammatory disease.

Virgin olive oil (VOO) is credited as being one of many healthful components of the Mediterranean diet. Mediterranean populations experience reduced incidence of chronic inflammatory disease states and VOO is readily consumed as part of an everyday dietary pattern. A phenolic compound contained in VOO, named oleocanthal, shares unique perceptual and anti-inflammatory characteristics with Ibuprofen. Over recent years oleocanthal has become a compound of interest in the search for naturally occurring compounds with pharmacological qualities. Subsequent to its discovery and identification, oleocanthal has been reported to exhibit various modes of action in reducing inflammatory related disease, including joint-degenerative disease, neuro-degenerative disease and specific cancers. Therefore, it is postulated that long term consumption of VOO containing oleocanthal may contribute to the health benefits associated with the Mediterranean dietary pattern. The following paper summarizes the current literature on oleocanthal, in terms of its sensory and pharmacological properties, and also discusses the beneficial, health promoting activities of oleocanthal, in the context of the molecular mechanisms within various models of disease.

Experiences and consequences of altered taste, flavour and food hedonics during chemotherapy treatment.

PURPOSE: Self-reported taste alterations are common in people receiving chemotherapy; however, it is usually unclear whether these reports refer to changes to the sense of taste itself or to problems related to the broader phenomenon of flavour, or the hedonic experience of eating and drinking. The purpose of this study was to explore patient and carer descriptions, experiences and consequences of taste and flavour changes associated with oxaliplatin treatment. METHODS: This study utilised a grounded theory research design. Purposeful sampling was used to recruit eligible patients who had self-reported taste changes in relation to oxaliplatin-containing chemotherapy for colorectal cancer. Content analysis of interview data was performed using an analysis framework derived from previous sensory and nutritional sciences and supportive care research. RESULTS: Ten patients and four carers participated in semi-structured interviews. The overarching theme identified from the data was reduced food enjoyment. In addition to changes to taste, participants described sensory and hedonic changes which influence overall flavour perception and food enjoyment. Reduced food enjoyment had dietary, social and emotional consequences for patients and carers. CONCLUSIONS: 'Taste' problems during oxaliplatin treatment mostly relate to the broader phenomena of flavour. This study has helped to unravel the major sensory determinants of the eating and drinking experience in the chemotherapy setting and has provided guidance regarding relevant and measurable endpoints of chemotherapy-related flavour changes. There remains a gap in knowledge between the pattern of flavour changes associated with chemotherapy treatment and how this influences dietary intake and nutritional status.

The influence of chemotherapy on taste perception and food hedonics: a systematic review.

PURPOSE: Altered food relationships in people receiving chemotherapy are prevalent and distressing. Whether, or to what extent, taste perception and food hedonics plays in altered food relationships is unknown among people receiving chemotherapy. This two-armed systematic review addressed the question "Does chemotherapy influence taste perception and hedonic experience of food?" METHODS: A systematic review was undertaken of (1) taste perception and (2) food hedonics. Search phrases used in the taste arm were: "chemotherapy AND taste", and in the food hedonics arm, "chemotherapy AND (liking OR food OR appetite OR hedonic(∗))". Databases searched were PsycINFO, PubMed, Medline, CINAHL, EMBASE and the Cochrane Library. English language, peer-reviewed publications investigating adults (>18years) receiving chemotherapy as the only cancer treatment were eligible. RESULTS: One hundred and sixty three papers were screened in the taste arm, of which eight (5%) met inclusion criteria. Nine hundred and seventy two papers were screened in the food hedonics arm of which 25 (3%) met inclusion criteria. Chemotherapy had variable influence on both taste sensitivity and perceived intensity of the taste qualities sweet, salty, sour and bitter. Liking of food and drink decreased after chemotherapy treatment commenced. Caffeinated foods and drinks, red meat and citrus fruits or juices were most frequently reported as aversive during chemotherapy. A reduction in appetite was reported between baseline (pre-chemotherapy) and cycles 1-3 of chemotherapy with no further worsening in latter chemotherapy cycles and an improvement after completion of chemotherapy treatment. CONCLUSIONS: There was a lack of consistency of results between studies due to differences in study design, chemotherapy regimen, tumor type and stage of treatment examined. These results provide insufficient evidence to suggest chemotherapy has a significant or consistent influence on taste. There is a consistent, albeit small, body of evidence indicating food liking and appetite are adversely affected by chemotherapy and some evidence that declines in liking and appetite are reversed over time. Overall, more longitudinal studies of specific classes of chemotherapy drugs are required to accurately define the nature, magnitude and time course of taste, food liking and appetite changes over the treatment trajectory.

Molecular mechanisms of inflammation. Anti-inflammatory benefits of virgin olive oil and the phenolic compound oleocanthal.

Chronic inflammation is a critical factor in the pathogenesis of many inflammatory disease states including cardiovascular disease, cancer, diabetes, degenerative joint diseases and neurodegenerative diseases. Chronic inflammatory states are poorly understood, however it is known that dietary habits can evoke or attenuate inflammatory responses. Popular methods to deal with inflammation and its associated symptoms involve the use of non steroidal anti-inflammatory drugs, however the use of these drugs are associated with severe side effects. Therefore, investigations concerned with natural methods of inflammatory control are warranted. A traditional Mediterranean diet has been shown to confer some protection against the pathology of chronic diseases through the attenuation of pro-inflammatory mediators and this has been partially attributed to the high intake of virgin olive oil accompanying this dietary regime. Virgin olive oil contains numerous phenolic compounds that exert potent anti-inflammatory actions. Of interest to this paper is the recently discovered phenolic compound oleocanthal. Oleocanthal is contained in virgin olive oil and possesses similar anti-inflammatory properties to ibuprofen. This pharmacological similarity has provoked interest in oleocanthal and the few studies conducted thus far have verified its anti-inflammatory and potential therapeutic actions. A review of the health benefits of the Mediterranean diet and anti-inflammatory properties of virgin olive oil is presented with the additional emphasis on the pharmacological and anti-inflammatory properties of the phenolic compound oleocanthal.

Biological activities of phenolic compounds present in virgin olive oil.

The Mediterranean diet is associated with a lower incidence of atherosclerosis, cardiovascular disease, neurodegenerative diseases and certain types of cancer. The apparent health benefits have been partially ascribed to the dietary consumption of virgin olive oil by Mediterranean populations. Much research has focused on the biologically active phenolic compounds naturally present in virgin olive oils to aid in explaining reduced mortality and morbidity experienced by people consuming a traditional Mediterranean diet. Studies (human, animal, in vivo and in vitro) have demonstrated that olive oil phenolic compounds have positive effects on certain physiological parameters, such as plasma lipoproteins, oxidative damage, inflammatory markers, platelet and cellular function, antimicrobial activity and bone health. This paper summarizes current knowledge on the bioavailability and biological activities of olive oil phenolic compounds.

Sensory characterization of the irritant properties of oleocanthal, a natural anti-inflammatory agent in extra virgin olive oils.

Oleocanthal is an olive oil phenolic possessing anti-inflammatory activity. Anecdotal evidence suggests that oleocanthal elicits a stinging sensation felt only at the back of the throat (oropharynx). Due to this compound possessing potentially health-benefiting properties, investigation into the sensory aspects of oleocanthal is warranted to aid in future research. The important link between the perceptual aspects of oleocanthal and health benefits is the notion that variation in sensitivity to oleocanthal irritation may relate to potential differences in sensitivity to the pharmacologic action of this compound. The current study assessed the unique irritant attributes of oleocanthal including its location of irritation, temporal profile, and individual differences in the perceived irritation. We show that the irritation elicited by oleocanthal was localized to the oropharynx (P < 0.001) with little or no irritation in the anterior oral cavity. Peak irritation was perceived 15 s postexposure and lasted over 180 s. Oleocanthal irritation was more variable among individuals compared with the irritation elicited by CO(2) and the sweetness of sucrose. There was no correlation between intensity ratings of oleocanthal and CO(2) and oleocanthal and sucrose (r = -0.15, n = 50, P = 0.92 and r = 0.17, n = 84, P = 0.12, respectively), suggesting that independent mechanisms underlie the irritation of CO(2) and oleocanthal. The unusual spatial localization and independence of acid (CO(2)) sensations suggest that distinct nociceptors for oleocanthal are located in the oropharyngeal region of the oral cavity.

Influence of heat on biological activity and concentration of oleocanthal--a natural anti-inflammatory agent in virgin olive oil.

The olive oil phenolic oleocanthal is a natural nonsteroidal anti-inflammatory compound that irritates the oral pharynx in a dose-dependent manner. It has been proposed that the biological activity of oleocanthal is partially responsible for the beneficial health effects of the Mediterranean diet. Virgin olive oil containing oleocanthal is often added as an ingredient in a number of cooked dishes, and therefore it is of great importance to understand how best to preserve the putative health-promoting benefits of this compound, as olive oil phenolics are subject to degradation upon heating in general. One extra virgin olive oil containing 53.9 mg/kg oleocanthal was heated at various temperatures (100, 170, and 240 degrees C) for set time periods (0, 1, 5, 20, 60, and 90 min). Oleocanthal concentrations were quantified using HPLC, and its biological activity was determined with a taste bioassay measuring the intensity of throat irritation. Results demonstrated that oleocanthal was heat stable compared with other olive oil phenolics, with a maximum loss of 16% as determined by HPLC analysis. However, there was a significant decrease of up to 31% (p < 0.05) in the biological activity of oleocanthal as determined by the taste bioassay. Although there was minimal degradation of oleocanthal concentration, there was a significant decrease in the biological activity of oleocanthal upon extended heating time, indicating a possible loss of the putative health -benefiting properties of oleocanthal. Alternatively, the difference in the concentration and biological activity of oleocanthal after heat treatment could be a result of an oleocanthal antagonist forming, decreasing or masking the biological activity of oleocanthal.

Chemistry and health of olive oil phenolics.

The Mediterranean diet is associated with a lower incidence of atherosclerosis, cardiovascular disease, and certain types of cancer. The apparent health benefits have been partially attributed to the dietary consumption of virgin olive oil by Mediterranean populations. Most recent interest has focused on the biologically active phenolic compounds naturally present in virgin olive oils. Studies (human, animal, in vivo and in vitro) have shown that olive oil phenolics have positive effects on certain physiological parameters, such as plasma lipoproteins, oxidative damage, inflammatory markers, platelet and cellular function, and antimicrobial activity. Presumably, regular dietary consumption of virgin olive oil containing phenolic compounds manifests in health benefits associated with a Mediterranean diet. This paper summarizes current knowledge on the physiological effects of olive oil phenolics. Moreover, a number of factors have the ability to affect phenolic concentrations in virgin olive oil, so it is of great importance to understand these factors in order to preserve the essential health promoting benefits of olive oil phenolic compounds.

Phytochemistry: ibuprofen-like activity in extra-virgin olive oil.

Newly pressed extra-virgin olive oil contains oleocanthal--a compound whose pungency induces a strong stinging sensation in the throat, not unlike that caused by solutions of the non-steroidal anti-inflammatory drug ibuprofen. We show here that this similar perception seems to be an indicator of a shared pharmacological activity, with oleocanthal acting as a natural anti-inflammatory compound that has a potency and profile strikingly similar to that of ibuprofen. Although structurally dissimilar, both these molecules inhibit the same cyclooxygenase enzymes in the prostaglandin-biosynthesis pathway.

The influence of sodium salts on binary mixtures of bitter-tasting compounds.

In order to study potential mixture interactions among bitter compounds, selected sodium salts were added to five compounds presented either alone or as binary bitter-compound mixtures. Each compound was tested at a concentration that elicited 'weak' perceived bitterness. The bitter compounds were mixed at these concentrations to form a subset of possible binary mixtures. For comparison, the concentration of each solitary compound was doubled to measure bitterness inhibition at the higher intensity level elicited by the mixtures. The following sodium salts were tested for bitterness inhibition: 100 mM sodium chloride (salty), 100 mM sodium gluconate (salty), 100 and 20 mM monosodium glutamate (umami), and 50 mM adenosine monophosphate disodium salt (umami). Sucrose (sweet) was also employed as a bitterness suppressor. The sodium salts differentially suppressed the bitterness of compounds and their binary combinations. Although most bitter compounds were suppressed, the bitterness of tetralone was not suppressed, nor was the bitterness of the binary mixtures that contained it. In general, the percent suppression of binary mixtures of compounds was predicted by the average percent suppression of its two components. Within the constraints of the present study, the bitterness of mixtures was suppressed by sodium salts and sucrose independently, with few bitter interactions. This is consistent with observations that the bitter taste system integrates the bitterness of multi-compound solutions linearly.

Modifying the bitterness of selected oral pharmaceuticals with cation and anion series of salts.

PURPOSE: NaCl has proven to be an effective bitterness inhibitor, but the reason remains unclear. The purpose of this study was to examine the influence of a variety of cations and anions on the bitterness of selected oral pharmaceuticals and bitter taste stimuli: pseudoephedrine, ranitidine, acetaminophen, quinine, and urea. METHOD: Human psychophysical taste evaluation using a whole mouth exposure procedure was used. RESULTS: The cations (all associated with the acetate anion) inhibited bitterness when mixed with pharmaceutical solutions to varying degrees. The sodium cation significantly (P < 0.003) inhibited bitterness of the pharmaceuticals more than the other cations. The anions (all associated with the sodium cation) also inhibited bitterness to varying degrees. With the exception of salicylate, the glutamate and adenosine monophosphate anions significantly (P < 0.001) inhibited bitterness of the pharmaceuticals more than the other anions. Also, there were several specific inhibitory interactions between ammonium, sodium and salicylate and certain pharmaceuticals. CONCLUSIONS: We conclude that sodium was the most successful cation and glutamate and AMP were the most successful anions at inhibiting bitterness. Structure forming and breaking properties of ions, as predicted by the Hofmeister series. and other physical-chemical ion properties failed to significantly predict bitterness inhibition.