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Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Context: Dietary zinc oxide (ZnO) (a bitter antimicrobial chemical) in pigs is being gradually phased out due to pollution and antibiotic resistance. Bitter compounds like quinine hydrochloride (HCl) have shown potential to enhance growth and feed efficiency by slowing gastric emptying and intestinal passage rates in pigs. Aims: This study aimed to evaluate quinine's ability to improve performance in weanling pigs without ZnO. Methods: Two experiments were conducted. Experiment 1: 120 Landrace (LD) × Large White (LW) weaned piglets (initial BW 6.8 ± 0.1 kg) were randomly assigned to one of four diets in a 2 × 2 factorial design: with/without ZnO and copper sulfate (CuSO4) (3000 and 250 ppm, respectively) and two quinine levels (0 and 500 ppm). Parameters measured included average daily feed intake (ADFI), average daily gain (ADG), gain to feed ratio (G:F), and faecal score. Experiment 2: 1440 LD × LW piglets (initial BW 7.4 ± 0.2 kg) were housed in groups of 18 per pen and assigned the same four dietary treatments as in Experiment 1. Key results: Growth performance parameters were recorded and analysed, showing that ZnO/CuSO4 supplement improved growth and feed efficiency (P < 0.05) compared to the ZnO/CuSO4-free diet group. In Experiment 1, pigs supplemented with quinine in non-ZnO/CuSO4 diets showed similar (P > 0.05) performance levels to the ZnO/CuSO4 fed group. In addition, an interaction (P < 0.05) was found, indicating that adding quinine improved or worsened ADG and G:F depending on the absence or presence of ZnO/CuSO4 in the diet, respectively. In Experiment 2, quinine inclusions in non-ZnO diets improved (P < 0.05) ADG but did not affect (P > 0.05) ADFI and G:F. Conclusion: Our findings suggest that the anticipated deleterious effects of phasing out the use of dietary ZnO can be partially compensated by includingquinine in the diet of post-weaning pigs. The negative effect of quinine when provided together with ZnO is compatible with a competitive exclusion mechanism linked to both stimulating bitterness, a mechanism that warrants further investigation. Implications: Quinine shows potential as a partial replacement for ZnO in post-weaning pig diets, providing a promising alternative to maintain piglet health and growth while transitioning away from ZnO. Quinine shows promise in improving the sustainability of pig farming by enhancing piglet growth while addressing environmental concerns linked to zinc oxide. Our studies revealed that quinine, comparable to traditional supplements, not only boosts piglet growth but also does so independently of zinc oxide showing promise as a viable alternative. This finding suggests that quinine could play a crucial role in promoting more sustainable pig nutrition practices. [ABSTRACT FROM AUTHOR]

Bitter food, because of its unique taste, is not popular with the public, and is even considered to be difficult to swallow. By binding to specific sites of bitter receptors (26 hTAS2Rs), bitter compounds activate the downstream signaling pathways mediated by G protein, which convert chemical signals into electrical signals that are ultimately transmitted to the brain to produce the bitter perception. The intensity of bitterness is mainly determined by the hydrophobic recognition region of bitter receptors. The bitter compounds in foods mainly include alkaloids, polyphenols, terpenoids, amino acids, etc. Foods rich in bitter taste are mostly natural such as beans, nuts, and coffee, etc. Studies have proven that bitter foods have biological activities such as preventing hyperlipidemia, hypertension, hyperglycemia, anti-inflammatory, antitumor, antibacterial, antioxidant, and exhibit neuroprotective effects and other biological activities. The purpose of this review is to explore the bitter perception and the biological activity of bitter compounds, clarify the mechanism of their action on human health, and provide theoretical guidance for the development and application of functional foods. [ABSTRACT FROM AUTHOR]

Gentiana lutea L. subsp. aurantiaca M. Lainz is a plant endemic to the north-western mountainous areas of the Iberian Peninsula. Its roots are widely used mainly because of the high content of bitter compounds. The occurrence of these valuable bitter compounds in the roots is rather inhomogeneous, resulting in fluctuating root quality. Methanolic extracts obtained from different parts and tissues of wild and cultivated gentian, in and out of its natural environment, were analysed using HPLC chromatography to investigate the variation in the concentration of amarogentin, gentiopicroside, sweroside and swertiamarin. The distribution patterns of these compounds in the different analysed fractions showed that the concentration of bitter compounds varies significantly. Amarogentin is much more highly concentrated in the secondary roots, and all of the analysed compounds were found in a significantly higher content in the root cortex than in the vascular tissues. Roots cultivated in the natural habitat showed much higher concentrations in amarogentin and more biomass, while in those cultivated out of the natural environment, sweroside concentration was higher. These results allow us to understand that, when cultivated, the variability in the concentration of the different bitter compounds is linked with the edaphoclimatic conditions, but more importantly that it is linked with the dominating kind of tissues and the root system structure, especially when analysing the content of amarogentin and sweroside. The selection of plants with an optimal root system structure for breeding may increase the yield in bitter compounds and contribute to developing the commercial cultivation of this protected plant. [ABSTRACT FROM AUTHOR]

Compounds that confer a bitter taste on fruits and vegetables (FAVs) play crucial roles in both plant defense and health promotion. This review details the current knowledge of the distribution, properties (toxicity, pharmacological effects and receptors) and environmental plant responses relating to the biosynthesis, catabolism and transcriptional regulation of 53 bitter plant metabolites in diverse species of FAVs. Some bitter compounds, such as flavonoids, are common in all plant species and make a minor contribution to bitter flavor, but many are synthesized only in specific taxa. They make major contributions to the bitter taste of the corresponding species and some also have significant pharmacological effects. Levels of bitter metabolites are genetically determined, but various environmental cues can affect their final concentration during preharvest development and postharvest storage processes. Molecular approaches are helping to unravel the mechanisms of biosynthesis and regulation of bitter compounds in diverse crop species. This review not only discusses the theoretical basis for utilizing breeding programs and other agricultural technologies to produce FAVs with improved safety, favorable taste and healthier profiles, but also suggests new directions for the utilization of bitter compounds in FAVs for the development of natural pesticides and health-promoting medicines. [ABSTRACT FROM AUTHOR]

Bitter food, because of its unique taste, is not popular with the public, and is even considered to be difficult to swallow. By binding to specific sites of bitter receptors (26 hTAS2Rs), bitter compounds activate the downstream signaling pathways mediated by G protein, which convert chemical signals into electrical signals that are ultimately transmitted to the brain to produce the bitter perception. The intensity of bitterness is mainly determined by the hydrophobic recognition region of bitter receptors. The bitter compounds in foods mainly include alkaloids, polyphenols, terpenoids, amino acids, etc. Foods rich in bitter taste are mostly natural such as beans, nuts, and coffee, etc. Studies have proven that bitter foods have biological activities such as preventing hyperlipidemia, hypertension, hyperglycemia, anti-inflammatory, antitumor, antibacterial, antioxidant, and exhibit neuroprotective effects and other biological activities. The purpose of this review is to explore the bitter perception and the biological activity of bitter compounds, clarify the mechanism of their action on human health, and provide theoretical guidance for the development and application of functional foods.

Bone marrow microenvironmental stimuli profoundly impact hematopoietic stem cell fate and biology. As G protein-coupled receptors, the bitter taste receptors (TAS2Rs) are key in transmitting extracellular stimuli into an intracellular response, within the oral cavity but also in extraoral tissues. Their expression in the bone marrow (BM)-derived cells suggests their involvement in sensing the BM microenvironmental fluctuation. In the present study, we demonstrated that umbilical cord blood (UCB)-derived CD34+ cells express fully functional TAS2Rs along with the signal transduction cascade components and their activation by the prototypical agonist, denatonium benzoate, significantly modulated genes involved in stemness maintenance and regulation of cell trafficking. The activation of these specific pathways was confirmed in functional in vitro experiments. Denatonium exposure exerted an antiproliferative effect on UCB-derived CD34+ cells, mainly affecting the most undifferentiated progenitor frequency. It also reduced their clonogenicity and repopulating potential in vitro. In addition, the TAS2R signaling activation impaired the UCB-derived CD34+ cell trafficking, mainly reducing the migration toward the chemoattractant agent CXCL12 and modulating the expression of the adhesion molecules CD62L, CD49d, and CD29. In conclusion, our results in UCB-derived CD34+ cells expand the observation of TAS2R expression in the setting of BM-resident cells and shed light on the role of TAS2Rs in the extrinsic regulation of hematopoietic stem cell functions. [ABSTRACT FROM AUTHOR]

Bitter compounds widely exist in foods and have an important impact on food flavor. The major bitter compounds in foods include amino acids, peptides, polyphenols, alkaloids, and inorganic salts. Bitterness is perceived through binding between bitter compounds and the specific sites of the 25 human bitter taste receptors (hTAS2Rs), which further activates the downstream signal pathway mediated by G protein, converting chemical signals into electrical signals and transmitting them to the brain. Some foods with strong bitterness taste are not well accepted by consumers, so appropriately reducing bitterness in foods can improve consumers’ preference. At present, there are two main methods to reduce the perception of food bitterness: 1) masking bitterness by polymerization/complexation or flavor interaction, and 2) removing bitterness by reducing the content of bitter compounds or changing their structure. In this paper, the bitter compounds in foods, the analytical methods for them, the mechanism of bitterness perception and the methods used to reduce bitterness perception are reviewed in an effort to provide theoretical guidance for food bitterness regulation.

Background: It’s known that respiratory diseases are the top of the list of systemic diseases, and accumulating evidence suggests that one of the important reasons for the high incidence of respiratory diseases is the difficulty in delivering drugs effectively to the respiratory system. Purpose: In this review, we summarized the potential roles of targeting T2Rs in combination with bitter compounds for the treatment of respiratory diseases, and also discussed the potential of ABC transmembrane transporter proteins to deliver bitter compounds to cells to combat drug resistance, providing a reference for future studies on bitter receptor therapy related to respiratory diseases. Results: The airway epithelium cells serve as a lung barrier against the invasion of various harmful substances in the respiratory system, and many receptors have been found to exist in the airway epithelium cells. Interestingly, it’s reported that lots of bitter compounds (quercetin, resveratrol, etc.) can reduce oxidative stress and other responses in respiratory diseases via bitter taste receptors (T2Rs). Conclusion: Collectively T2Rs, seem as feasible drug targets and alternative treatment option for for natural bitter agents from traditional Chinese medicine to respiratory diseases in the future.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The bitter taste is generally considered an undesirable sensory attribute. However, bitter‐tasting compounds can significantly affect the overall flavor of many foods and beverages and endow them with various beneficial effects on human health. To better understand the relationship between chemical structure and bitterness, this paper has summarized the bitter compounds in foodstuffs and classified them based on the basic skeletons. Only those bitter compounds that are confirmed by human sensory evaluation have been included in this paper. To develop food products that satisfy consumer preferences, correctly ranking the key bitter compounds in foodstuffs according to their contributions to the overall bitterness intensity is the precondition. Generally, three methods were applied to screen out the key bitter compounds in foods and beverages and evaluate their sensory contributions, including dose‐over‐threshold factors, taste dilution analysis, and spectrum descriptive analysis method. This paper has discussed in detail the mechanisms and applications of these three methods. Typical procedures for separating and identifying the main bitter compounds in foodstuffs have also been summarized. Additionally, the activation of human bitter taste receptors (TAS2Rs) and the mechanisms of bitter taste transduction are outlined. Ultimately, a conclusion has been drawn to highlight the current problems and propose potential directions for further research. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tea Science is the property of Journal of Tea Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is important to identify the bitter substances in natural compounds and determine their bitterness threshold for finding out the bitter molecules that affect the flavor of food and developing some foods with unique flavors. Identifying bitter molecules and predicting the threshold of bitter molecules based on the quantitative structure-activity relationship is a low-cost and rapid method. This research used Molecular Operating Environment (MOE), Chemopy and Mordred to generate 2D molecular descriptor to establish bitterness molecular recognition models with Support Vector Machine (SVM) and Random Forests (RF) algorithms. This study used above descriptors to establish bitterness threshold prediction models with Partial Least Squares Regression (PLSR), Random Forests Regression (RFR), k-Nearest Neighbor Regression (kNNR), and Principle Component Regression (PCR) algorithms. The results showed that the MOE-RF model had the highest accuracy of 0.982, the ChemoPy-PLSR model had the best bitterness prediction effect with a coefficient of determination of 0.85 and a root mean square error of 0.43. The two models would be combined to predict whether the molecule has bitterness and the threshold of bitterness or not.

Trub, a brewing by-product, can be used as alternative ingredient for foods nutritional enrichment after its bitter compounds extraction. Study presents the optimisation of bitter compounds extraction from trub by Box-Behnken design, and use of debittered trub (DT) as new ingredient to enrich pasta. Bitterness extraction process was evaluated at different pH levels, time and extraction steps, and physical-chemical properties of DT (obtained under optimal conditions) were evaluated. Pasta was enriched with DT (5%, 10% and 15%) and its physical-chemical and quality properties were evaluated. Protein structure and chemical composition of trub were altered after process, also modifying its technological properties. Pasta with 10% DT increased in 33.51% protein content. Interaction of DT and wheat proteins resulted in a more compact structure, and DT water absorption capacity provided pasta texture changes. DT use improved pasta nutritional and quality properties, enabling trub valorisation and its use as vegetable proteins alternative source. [ABSTRACT FROM AUTHOR]

Abstract Bitter taste-sensing type 2 receptors (TAS2Rs or T2Rs), belonging to the subgroup of family A G-protein coupled receptors (GPCRs), are of crucial importance in the perception of bitterness. Although in the first instance, TAS2Rs were considered to be exclusively distributed in the apical microvilli of taste bud cells, numerous studies have detected these sensory receptor proteins in several extra-oral tissues, such as in pancreatic or ovarian tissues, as well as in their corresponding malignancies. Critical points of extra-oral TAS2Rs biology, such as their structure, roles, signaling transduction pathways, extensive mutational polymorphism, and molecular evolution, have been currently broadly studied. The TAS2R cascade, for instance, has been recently considered to be a pivotal modulator of a number of (patho)physiological processes, including adipogenesis or carcinogenesis. The latest advances in taste receptor biology further raise the possibility of utilizing TAS2Rs as a therapeutic target or as an informative index to predict treatment responses in various disorders. Thus, the focus of this review is to provide an update on the expression and molecular basis of TAS2Rs functions in distinct extra-oral tissues in health and disease. We shall also discuss the therapeutic potential of novel TAS2Rs targets, which are appealing due to their ligand selectivity, expression pattern, or pharmacological profiles.

The taste of blue honeysuckle (Lonicera caerulea L.) berries is wrapped in bitterness, and awareness about the essence of bitterness is lacking. In the current study, 7-ketologanin, sweroside and loganin were isolated and identified as key bitter compounds using sensory-guided analysis. The bitterness thresholds of these compounds were determined to be 11.9 μg/mL, 33.5 μg/mL and 60.2 μg/mL. Subsequently, the differences in bitterness among 16 blue honeysuckle varieties were evaluated. The wild varieties A1 and A2 exhibited the highest bitter intensity. 7-Ketologanin, with the highest concentration of 34.70–37.11 mg/100 g and taste activity values of 29.16–31.18 in A1 and A2, was first identified as a bitter contributor in blue honeysuckle. There was no significant difference in bitter intensity between the reconstitution model and the original sample, confirming the contribution of the three bitter compounds. This study lays the foundation for the bitter improvement and variety selection of blue honeysuckle resources. [Display omitted] • There were 32 potential bitter compounds identified in blue honeysuckle berries. • 7-Ketologanin was firstly identified in blue honeysuckle berries. • 7-Ketologanin, sweroside and loganin were determined as the key bitter compounds. • The threshold values of 3 bitter compounds in water were firstly determined. • Bitter differences were explored among 16 blue honeysuckle varieties. [ABSTRACT FROM AUTHOR]

Papaya fruit is one of economic crops in Taiwan, mostly eaten as table fruits. In some Asian countries, unripe papaya fruit is eaten as salad and this led to trends in Taiwan as well. However, unripe papaya fruit may taste bitter during cool seasons. Glucosinolate and cyanogenic glucoside are among the substances that cause bitter taste in many plants, which can also be found in papaya. However, there is still no report about the relationship between seasons and bitter taste in papaya fruits. Thus, the purpose of this study is to investigate the glucosinolate biosynthesis and its correlation between bitterness intensity during cool and warm seasons. The bitterness intensity was highest at the young fruit stage and decreased as it developed. In addition, the bitterness intensity in cool season fruits is higher than in warm season fruits. Cyanogenic glucoside and BITC content showed negative correlation with bitterness intensity (r = −0.54 ***; −0.46 ***). Phenylalanine showed positive correlation with bitterness intensity (r = 0.35 ***), but its content did not reach the bitterness threshold concentration, which suggested that phenylalanine only acts as cyanogenic glucoside and glucosinolate precusors. Glucosinolate content showed positive correlation with bitterness intensity at different developmental stages (r = 0.805 ***). However, the correlation value in different lines/cultivars decreased (0.44 ***), suggesting that glucosinolate was not the only substance that caused bitter taste in immature papaya fruits. [ABSTRACT FROM AUTHOR]

Bitter taste-sensing type 2 receptors (TAS2Rs or T2Rs), belonging to the subgroup of family A G-protein coupled receptors (GPCRs), are of crucial importance in the perception of bitterness. Although in the first instance, TAS2Rs were considered to be exclusively distributed in the apical microvilli of taste bud cells, numerous studies have detected these sensory receptor proteins in several extra-oral tissues, such as in pancreatic or ovarian tissues, as well as in their corresponding malignancies. Critical points of extra-oral TAS2Rs biology, such as their structure, roles, signaling transduction pathways, extensive mutational polymorphism, and molecular evolution, have been currently broadly studied. The TAS2R cascade, for instance, has been recently considered to be a pivotal modulator of a number of (patho)physiological processes, including adipogenesis or carcinogenesis. The latest advances in taste receptor biology further raise the possibility of utilizing TAS2Rs as a therapeutic target or as an informative index to predict treatment responses in various disorders. Thus, the focus of this review is to provide an update on the expression and molecular basis of TAS2Rs functions in distinct extra-oral tissues in health and disease. We shall also discuss the therapeutic potential of novel TAS2Rs targets, which are appealing due to their ligand selectivity, expression pattern, or pharmacological profiles. [ABSTRACT FROM AUTHOR]

Roots of Gentiana purpurea are known to have an intense bitter taste due to its high content of secoiridoids. In folk medicine roots have commonly been prepared as water decoctions, soaked in ethanol, or boiled with milk, wine, or beer. The aim of this study was to explore how various historical preparation methods influence yields of major bitter compounds in G. purpurea. HPLC-DAD analysis revealed that maceration with 40% and 70% ethanol, boiling with acetic acid (3% and 6%), vinegar and raw milk gave the highest extraction yields of gentiopicrin. Erythrocentaurin was detected when the roots were added to cold water before boiling, possibly because of enzymatic degradation. In contrast, erythrocentaurin was not detected in preparations where roots were added to boiling water, or when they were extracted with acetic acid or alcohol. The results stress the significance of traditional preparation methods to optimize yield of bioactive compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

De‐oiled canola meals are sources of protein‐containing flavor‐active phenolic compounds. Conventional canola oil processing utilizes an excess amount of solvents and is associated with the release of high‐intensity bitter flavor‐active phenolic compounds, limiting the use of the canola meal. Recent advances in the extraction and isolation of the bitter favor‐active phenolic compounds from canola by‐products produce protein isolates, however, would benefit the industry by producing a side‐stream ingredient rich in phenolics. High temperature and pressure‐aided processing, namely the accelerated solvent extraction (ASE) was investigated to extract the flavor‐active bitter molecules from the canola meal. The extractability of flavor‐active phenolic compounds including the major sinapates, kaempferol derivatives, and other thermo‐generative compounds including thomasidioc acid (TA) was evaluated. The effects of temperature, solvent extractant and concentration, and the particle size of the meal were examined on the extraction efficiency of these phenolic compounds. Extraction temperature (180°C) was the primary determinant (p < 0.05) for the attenuation of major sinapates including sinapine and sinapic acid. Both ethanol and methanol extractants at a concentration of 70% (v/v) significantly (p < 0.05) extracted the flavor‐active phenolic compounds. The pressurized high temperature through optimized ASE conditions attenuated the bitter undesirable flavor‐active phenolic molecules from canola meal, thereby facilitating a potential value‐added phenolic‐rich by‐product. [ABSTRACT FROM AUTHOR]

Although most Drosophila species lay eggs in overripe fruit, the agricultural pest Drosophila suzukii lays eggs in ripe fruit. We found that changes in bitter taste perception have accompanied this adaptation. We show that bitter-sensing mutants of Drosophila melanogaster undergo a shift in egg laying preference toward ripe fruit. D. suzukii has lost 20% of the bitter-sensing sensilla from the labellum, the major taste organ of the head. Physiological responses to various bitter compounds are lost. Responses to strawberry purées are lost from two classes of taste sensilla. Egg laying is not deterred by bitter compounds that deter other species. Profiling of labellar transcriptomes reveals reduced expression of several bitter Gr genes (gustatory receptors). These findings support a model in which bitter compounds in early ripening stages deter egg laying in most Drosophila species, but a loss of bitter response contributes to the adaptation of D. suzukii to ripe fruit.

The contribution of cell-extrinsic factors in Acute Myeloid Leukemia (AML) generation and persistence has gained interest. Bitter taste receptors (TAS2Rs) are G protein-coupled receptors known for their primary role as a central warning signal to induce aversion toward noxious or harmful substances. Nevertheless, the increasing amount of evidence about their extra-oral localization has suggested a wider function in sensing microenvironment, also in cancer settings. In this study, we found that AML cells express functional TAS2Rs. We also highlighted a significant association between the modulation of some TAS2Rs and the poor-prognosis AML groups, i.e., TP53- and TET2-mutated, supporting a potential role of TAS2Rs in AML cell biology. Gene expression profile analysis showed that TAS2R activation with the prototypical agonist, denatonium benzoate, significantly modulated a number of genes involved in relevant AML cellular processes. Functional assay substantiated molecular data and indicated that denatonium reduced AML cell proliferation by inducing cell cycle arrest in G0/G1 phase or induced apoptosis via caspase cascade activation. Moreover, denatonium exposure impaired AML cell motility and migratory capacity, and inhibited cellular respiration by decreasing glucose uptake and oxidative phosphorylation. In conclusion, our results in AML cells expand the observation of cancer TAS2R expression to the setting of hematological neoplasms and shed light on a role of TAS2Rs in the extrinsic regulation of leukemia cell functions.

• Analysis using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) was conducted to screen for the content of amygdalin in the fruit flesh of 'Katy' and 'Kuijin' apricots at 42 and 84 days after full bloom (DAF). The results showed that the content of amygdalin in both cultivars was higher at 84 DAF compared to 42 DAF. Additionally, at 84 DAF, 'Kuijin' had a higher content of amygdalin compared to 'Katy'. • The bitter compounds in 'Katy' and 'Kuijin' apricots are not limited to amygdalin; they also contain 44 other compounds, with the most abundant being 19 phenolic compounds. • A key transcription factor, PARG18533 , regulating the transcription of the enzyme involved in amygdalin synthesis, was identified. This transcription factor belongs to the bHLH family. Interestingly, the transcription factor regulating amygdalin synthesis in the bitter almond's kernel has leucine at position 371, while the sweet almond has phenylalanine. The PARG18533 transcription factor also has leucine at position 371. • KEGG enrichment analysis of these differentially expressed genes revealed that phenolic compounds were mainly enriched in the flavonoid biosynthesis pathway. There are a total of 18 differentially expressed genes and 21 UDP-glycosyltransferases (UGTs) in the way. A phylogenetic tree analysis was performed on 21 UDP-glycosyltransferases and known functional glycosyltransferases, which classified them into five branches. Among the 44 substances, the glycosyltransferases associated with them were assigned to branches C, D, and e. Analysis of the fruit flesh of 'Katy' and 'Kuijin' apricots at 42 and 84 days after full (DAF) bloom was conducted using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) to screen for potential bitter compounds during different developmental stages. Transcriptomic approaches were employed to identify key genes involved in the synthesis of bitter compounds during different developmental stages, based on public databases and a self-built database by Maevi. Results showed that the ripe stage of 'Kuijin' apricots had higher levels of amygdalin, a bitter compound, compared to 'Katy'. The apricot fruit flesh also contained 44 other bitter compounds, including 19 phenolic compounds. Bitter compound variations between developmental phases were larger than those between varieties. The 8 phenolic compounds revealed greater amounts during the young fruit stage of 'Kuijin' compared to both the ripe stage of 'Kuijin' and the young fruit stage of 'Katy'. Differential gene screening identified two genes, PARG26876 and PARG24542 , belonging to the CYP79 and CYP71 subfamilies of cytochrome P450 enzymes involved in amygdalin synthesis, respectively. PARG18533 is the bHLH2 homolog gene that may regulate the transcription of these two genes in apricot flesh. KEGG enrichment analysis of differential genes revealed that phenolic compounds were mainly enriched in flavonoid biosynthesis and flavone and flavonol biosynthesis pathways. There were 18 structural genes and 21 UDP-glycosyltransferases implicated in these two pathways. Evolutionary tree analysis of UDP-glycosyltransferases identified that 13 glycosyltransferases formed five distinct branches, with three genes associated with the synthesis of bitter compounds situated in branches C, D, and E. [ABSTRACT FROM AUTHOR]

Papaya fruit is one of economic crops in Taiwan, mostly eaten as table fruits. In some Asian countries, unripe papaya fruit is eaten as salad and this led to trends in Taiwan as well. However, unripe papaya fruit may taste bitter during cool seasons. Glucosinolate and cyanogenic glucoside are among the substances that cause bitter taste in many plants, which can also be found in papaya. However, there is still no report about the relationship between seasons and bitter taste in papaya fruits. Thus, the purpose of this study is to investigate the glucosinolate biosynthesis and its correlation between bitterness intensity during cool and warm seasons. The bitterness intensity was highest at the young fruit stage and decreased as it developed. In addition, the bitterness intensity in cool season fruits is higher than in warm season fruits. Cyanogenic glucoside and BITC content showed negative correlation with bitterness intensity (r = −0.54 ***; −0.46 ***). Phenylalanine showed positive correlation with bitterness intensity (r = 0.35 ***), but its content did not reach the bitterness threshold concentration, which suggested that phenylalanine only acts as cyanogenic glucoside and glucosinolate precusors. Glucosinolate content showed positive correlation with bitterness intensity at different developmental stages (r = 0.805 ***). However, the correlation value in different lines/cultivars decreased (0.44 ***), suggesting that glucosinolate was not the only substance that caused bitter taste in immature papaya fruits.

Significant advances have been made in the past decade in mapping the distributions and the physiological functions of extra-oral bitter taste receptors (TAS2Rs) in non-gustatory tissues. In particular, it has been found that TAS2Rs are expressed in various muscle tissues and activation of TAS2Rs can lead to muscle cell relaxation, which suggests that TAS2Rs may be important new targets in muscle relaxation therapy for various muscle-related diseases. So far, however, there is a lack of potent extra-oral TAS2R agonists that can be used as novel drug agents in muscle relaxation therapies. Interestingly, traditional Chinese medicine (TCM) often characterizes a drug’s property in terms of five distinct flavors (bitter, sweet, sour, salty, and pungent) according to its taste and function, and commonly regards “bitterness” as an intrinsic property of “good medicine.” In addition, many bitter flavored TCM are known in practice to cause muscle relaxation after long term use, and in lab experiments the compounds identified from some bitter flavored TCM do activate TAS2Rs and thus relax muscle cells. Therefore, it is highly possible to discover very useful extra-oral TAS2R agonists for muscle relaxation therapies among the abundant bitter compounds used in bitter flavored TCM. With this perspective, we reviewed in literature the distribution of TAS2Rs in different muscle systems with a focus on the map of bitter flavored TCM which can regulate muscle contractility and related functional chemical components. We also reviewed the recently established databases of TCM chemical components and the bioinformatics software which can be used for high-throughput screening and data mining of the chemical components associated with bitter flavored TCM. All together, we aim to present a knowledge-based approach and technological platform for identification or discovery of extra-oral TAS2R agonists that can be used as novel drug agents for muscle relaxation therapies through screening and evaluation of chemical compounds used in bitter flavored TCM.

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Significant advances have been made in the past decade in mapping the distributions and the physiological functions of extra-oral bitter taste receptors (TAS2Rs) in non-gustatory tissues. In particular, it has been found that TAS2Rs are expressed in various muscle tissues and activation of TAS2Rs can lead to muscle cell relaxation, which suggests that TAS2Rs may be important new targets in muscle relaxation therapy for various muscle-related diseases. So far, however, there is a lack of potent extra-oral TAS2R agonists that can be used as novel drug agents in muscle relaxation therapies. Interestingly, traditional Chinese medicine (TCM) often characterizes a drug's property in terms of five distinct flavors (bitter, sweet, sour, salty, and pungent) according to its taste and function, and commonly regards "bitterness" as an intrinsic property of "good medicine." In addition, many bitter flavored TCM are known in practice to cause muscle relaxation after long term use, and in lab experiments the compounds identified from some bitter flavored TCM do activate TAS2Rs and thus relax muscle cells. Therefore, it is highly possible to discover very useful extra-oral TAS2R agonists for muscle relaxation therapies among the abundant bitter compounds used in bitter flavored TCM. With this perspective, we reviewed in literature the distribution of TAS2Rs in different muscle systems with a focus on the map of bitter flavored TCM which can regulate muscle contractility and related functional chemical components. We also reviewed the recently established databases of TCM chemical components and the bioinformatics software which can be used for high-throughput screening and data mining of the chemical components associated with bitter flavored TCM. All together, we aim to present a knowledge-based approach and technological platform for identification or discovery of extra-oral TAS2R agonists that can be used as novel drug agents for muscle relaxation therapies through screening and evaluation of chemical compounds used in bitter flavored TCM. [ABSTRACT FROM AUTHOR]

The 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one (DDMP), 5-hydroxymethylfurfural (HMF), furfural, and 5-methylfurfural (MF) are the components of caramel colors with intense bitterness. In this study, a practical and simple method for the simultaneous analysis of these four bitter compounds in caramel colors and beverages was proposed using high-performance liquid chromatography–diode array detector–atmospheric pressure chemical ionization–mass spectrometry (HPLC-DAD-APCI-MS). For the sample preparation, the extract efficiencies from different extract solvents and quick, easy, cheap, effective, rugged, and safe (QuEChERS) salt pockets were compared. The correlation coefficients (R2) of all analytical curves were ≥ 0.9914. The satisfactory recoveries ranged between 70.1% and 101.5%, with relative standard deviations ranged from 1.7% to 9.1%. The matrix effect was evaluated, and HMF, furfural, and MF showed signal enrichment. This method was successfully applied to the analysis of bitter compounds content in several caramel colors and beverages from a local market in China. Four compounds were found in eight samples, with concentration ranging from 0.5 to 1058.1 mg kg−1. [ABSTRACT FROM AUTHOR]

• Bitter and sweet compounds are numerous and structurally diverse. • The majority of bitter compounds have higher hydrophobicity and more narrow range of sizes than sweet compounds. • hERG potassium channel, cytochrome P450 enzymes and carbonic anhydrases are common off-targets of bitterants. "Bitter" and "sweet" are frequently framed in opposition, both functionally and metaphorically, in regard to affective responses, emotion, and nutrition. This oppositional relationship is complicated by the fact that some molecules are simultaneously bitter and sweet. In some cases, a small chemical modification, or a chirality switch, flips the taste from sweet to bitter. Molecules humans describe as bitter are recognized by a 25-member subfamily of class A G-protein coupled receptors (GPCRs) known as TAS2Rs. Molecules humans describe as sweet are recognized by a TAS1R2/TAS1R3 heterodimer of class C GPCRs. Here we characterize the chemical space of bitter and sweet molecules: the majority of bitter compounds show higher hydrophobicity compared to sweet compounds, while sweet molecules have a wider range of sizes. Importantly, recent evidence indicates that TAS1Rs and TAS2Rs are not limited to the oral cavity; moreover, some bitterants are pharmacologically promiscuous, with the hERG potassium channel, cytochrome P450 enzymes, and carbonic anhydrases as common off-targets. Further focus on polypharmacology may unravel new physiological roles for tastant molecules. [ABSTRACT FROM AUTHOR]

Summary: The use of agro‐industrial waste for food enrichment can be limited, due to taste, odour, colour and other unpleasant characteristics. Trub (brewing waste) has important nutrients, such as proteins and carbohydrates, and phytochemical compounds; however, its applications are hindered by the astringent flavour. In order to reduce the bitterness of trub, aqueous extractions were realized at high temperature (100 °C per 1 h) in five steps. Two fractions were obtained; a liquid fraction (containing bitter compounds) and a solid fraction (the trub after the extraction process; TAP). Both fractions and the trub before the extraction process (TBP) were evaluated. The bitterness of TBP was significantly reduced in TAP while the protein content increased; TAP presented a branched network and changes in its structure. The reduction in bitterness and the high protein content allows the use of trub in the food industry. [ABSTRACT FROM AUTHOR]

It's known that respiratory diseases are the top of the list of systemic diseases, and accumulating evidence suggests that one of the important reasons for the high incidence of respiratory diseases is the difficulty in delivering drugs effectively to the respiratory system. In this review, we summarized the potential roles of targeting T2Rs in combination with bitter compounds for the treatment of respiratory diseases, and also discussed the potential of ABC transmembrane transporter proteins to deliver bitter compounds to cells to combat drug resistance, providing a reference for future studies on bitter receptor therapy related to respiratory diseases. The airway epithelium cells serve as a lung barrier against the invasion of various harmful substances in the respiratory system, and many receptors have been found to exist in the airway epithelium cells. Interestingly, it's reported that lots of bitter compounds (quercetin, resveratrol, etc.) can reduce oxidative stress and other responses in respiratory diseases via bitter taste receptors (T2Rs). Collectively T2Rs, seem as feasible drug targets and alternative treatment option for for natural bitter agents from traditional Chinese medicine to respiratory diseases in the future. [ABSTRACT FROM AUTHOR]

Huanglongbing (HLB) or citrus greening is the most severe citrus disease, currently devastating the citrus industry worldwide. The presumed causal bacterial agent Candidatus Liberibacter spp. affects tree health as well as fruit development, ripening and quality of citrus fruits and juice. Fruit from infected orange trees can be either symptomatic or asymptomatic. Symptomatic oranges are small, asymmetrical and greener than healthy fruit. Furthermore, symptomatic oranges show higher titratable acidity and lower soluble solids, solids/acids ratio, total sugars, and malic acid levels. Among flavor volatiles, ethyl butanoate, valencene, decanal and other ethyl esters are lower, but many monoterpenes are higher in symptomatic fruit compared to healthy and asymptomatic fruit. The disease also causes an increase in secondary metabolites in the orange peel and pulp, including hydroxycinnamic acids, limonin, nomilin, narirutin, and hesperidin. Resulting from these chemical changes, juice made from symptomatic fruit is described as distinctly bitter, sour, salty/umami, metallic, musty, and lacking in sweetness and fruity/orange flavor. Those effects are reported in both Valencia and Hamlin oranges, two cultivars that are commercially processed for juice in Florida. The changes in the juice are reflective of a decrease in quality of the fresh fruit, although not all fresh fruit varieties have been tested. Earlier research showed that HLB-induced off-flavor was not detectable in juice made with up to 25% symptomatic fruit in healthy juice, by chemical or sensory analysis. However, a blend with a higher proportion of symptomatic juice would present a detectable and recognizable off flavor. In some production regions, such as Florida in the United States, it is increasingly difficult to find fruit not showing HLB symptoms. This review analyzes and discusses the effects of HLB on orange juice quality in order to help the citrus industry manage the quality of orange juice, and guide future research needs.

Huanglongbing (HLB) or citrus greening is the most severe citrus disease, currently devastating the citrus industry worldwide. The presumed causal bacterial agent Candidatus Liberibacter spp. affects tree health as well as fruit development, ripening and quality of citrus fruits and juice. Fruit from infected orange trees can be either symptomatic or asymptomatic. Symptomatic oranges are small, asymmetrical and greener than healthy fruit. Furthermore, symptomatic oranges show higher titratable acidity and lower soluble solids, solids/acids ratio, total sugars, and malic acid levels. Among flavor volatiles, ethyl butanoate, valencene, decanal and other ethyl esters are lower, but many monoterpenes are higher in symptomatic fruit compared to healthy and asymptomatic fruit. The disease also causes an increase in secondary metabolites in the orange peel and pulp, including hydroxycinnamic acids, limonin, nomilin, narirutin, and hesperidin. Resulting from these chemical changes, juice made from symptomatic fruit is described as distinctly bitter, sour, salty/umami, metallic, musty, and lacking in sweetness and fruity/orange flavor. Those effects are reported in both Valencia and Hamlin oranges, two cultivars that are commercially processed for juice in Florida. The changes in the juice are reflective of a decrease in quality of the fresh fruit, although not all fresh fruit varieties have been tested. Earlier research showed that HLB-induced off-flavor was not detectable in juice made with up to 25% symptomatic fruit in healthy juice, by chemical or sensory analysis. However, a blend with a higher proportion of symptomatic juice would present a detectable and recognizable off flavor. In some production regions, such as Florida in the United States, it is increasingly difficult to find fruit not showing HLB symptoms. This review analyzes and discusses the effects of HLB on orange juice quality in order to help the citrus industry manage the quality of orange juice, and guide future research needs. [ABSTRACT FROM AUTHOR]

Differences in the taste profile of corn puffed products formulated with refined versus whole grain mix flour were characterized. The perceived bitter intensity was reported to be the main taste difference between the samples. Based on multidimensional sensory-guided fractionation techniques and subsequent identification by MS and NMR analysis, the primary bitter compounds identified in the whole grain sample were l -tryptophan, chaenorpine, N 1 , N 5 -Di-[ E ]- p -coumaroyl-spermidine, and terrestribisamide. All compounds were reported to contribute to bitterness perception at the concentrations reported in the saliva after mastication of the extruded products; chaenorphine had the highest contribution to the perceived bitterness. All bitter compounds were endogenous products of the corn. [ABSTRACT FROM AUTHOR]

Chickens sense the bitter taste of structurally different molecules with merely three bitter taste receptors (Gallus gallus taste 2 receptors, ggTas2rs), representing a minimal case of bitter perception. Some bitter compounds like quinine, diphenidol and chlorpheniramine, activate all three ggTas2rs, while others selectively activate one or two of the receptors. We focus on bitter compounds with different selectivity profiles toward the three receptors, to shed light on the molecular recognition complexity in bitter taste. Using homology modeling and induced-fit docking simulations, we investigated the binding modes of ggTas2r agonists. Interestingly, promiscuous compounds are predicted to establish polar interactions with position 6.51 and hydrophobic interactions with positions 3.32 and 5.42 in all ggTas2rs; whereas certain residues are responsible for receptor selectivity. Lys3.29 and Asn3.36 are suggested as ggTas2r1-specificity-conferring residues; Gln6.55 as ggTas2r2-specificity-conferring residue; Ser5.38 and Gln7.42 as ggTas2r7-specificity conferring residues. The selectivity profile of quinine analogs, quinidine, epiquinidine and ethylhydrocupreine, was then characterized by combining calcium-imaging experiments and in silico approaches. ggTas2r models were used to virtually screen BitterDB compounds. ~50% of compounds known to be bitter to human are likely to be bitter to chicken, with 25, 20, 37% predicted to be ggTas2r1, ggTas2r2, ggTas2r7 agonists, respectively. Predicted ggTas2rs agonists can be tested with in vitro and in vivo experiments, contributing to our understanding of bitter taste in chicken and, consequently, to the improvement of chicken feed.

In citrus color mutants, the levels of carotenoid constituents and other secondary metabolites are different in their corresponding wild types. Terpenoids are closely related to coloration, bitterness, and flavor. In this study, terpenoid profiles and hormones in citrus fruits of two red-flesh mutants—Red Anliu orange and Red-flesh Guanxi pummelo—and their corresponding wild types were investigated using GC/MS, HPLC, and LC-MS/MS. Results showed that Red Anliu orange (high in carotenoids) and Anliu orange (low in carotenoids) accumulated low levels of limonoid aglycones but high levels of monoterpenoids; conversely, Red-flesh Guanxi pummelo (high in carotenoids) and Guanxi pummelo (deficient in carotenoids) accumulated high levels of limonoid aglycones but low levels of monoterpenoids. However, isopentenyl diphosphate was present at similar levels. A correlation analysis indicated that jasmonic and salicylic acids might play important roles in regulating terpenoid biosynthesis. Additionally, the similarities of carotenoid and volatile profiles between each mutant and its corresponding wild type were greater than those between the two mutants or the two wild types. The flux balance of terpenoid metabolism in citrus fruit tends toward stability among various citrus genera that have different terpenoid profiles. Bud mutations could influence metabolite profiles of citrus fruit to a limited extent.

The pathogenic bacterium Streptococcus pneumoniae (S. pneumoniae) can invade the cerebrospinal fluid (CSF) and cause meningitis with devastating consequences. Whether and how sensory cells in the central nervous system (CNS) become activated during bacterial infection, as recently reported for the peripheral nervous system, is not known. We find that CSF infection by S. pneumoniae in larval zebrafish leads to changes in posture and behavior that are reminiscent of pneumococcal meningitis, including dorsal arching and epileptic-like seizures. We show that during infection, invasion of the CSF by S. pneumoniae massively activates in vivo sensory neurons contacting the CSF, referred to as "CSF-cNs" and previously shown to detect spinal curvature and to control posture, locomotion, and spine morphogenesis. We find that CSF-cNs express orphan bitter taste receptors and respond in vitro to bacterial supernatant and metabolites via massive calcium transients, similar to the ones observed in vivo during infection. Upon infection, CSF-cNs also upregulate the expression of numerous cytokines and complement components involved in innate immunity. Accordingly, we demonstrate, using cell-specific ablation and blockade of neurotransmission, that CSF-cN neurosecretion enhances survival of the host during S. pneumoniae infection. Finally, we show that CSF-cNs respond to various pathogenic bacteria causing meningitis in humans, as well as to the supernatant of cells infected by a neurotropic virus. Altogether, our work uncovers that central sensory neurons in the spinal cord, previously involved in postural control and morphogenesis, contribute as well to host survival by responding to the invasion of the CSF by pathogenic bacteria during meningitis. [Display omitted] • Infection of zebrafish with S. pneumoniae elicits pathognomonic signs of meningitis • CSF-cNs show massive activation when S. pneumoniae invade the CSF • Metabolites secreted by S. pneumoniae induce similar activation of CSF-cNs • CSF-cN secretion increases host survival upon S. pneumoniae infection Prendergast et al. discover that cerebrospinal fluid-contacting neurons (CSF-cNs), which are known to detect spinal curvature and control posture, also respond to bacterial metabolites, and during infections of the central nervous system, they secrete compounds that promote host survival. [ABSTRACT FROM AUTHOR]

Calibration models were developed for simultaneous analysis of alcohol, real extract, energy value, total saccharides and other features in beer using Fourier-transform near-infrared (FT-NIR) spectroscopy. The recorded FT-NIR spectra were correlated to the analytical data of reference methods by means of the multivariate PLS algorithm. Two groups of test beers were made from barley from two consecutive harvests. A calibration model for FT-NIR was set up using data from reference methods and was selected by means of the error of calibration (RMSEC), cross-validation (RMSECV), and the root-mean-square-error of prediction (RMSEP). It was found that calibration models for energy value, alcohol, real extract and the content of saccharides are stable and reliable. The long-term effect of calibration was evaluated by comparing external validation parameters, expressed as RMSEPex.

The bitter compounds in cigarette smoke have non-volatility, diversity and low-abundance. Sensory-oriented separation followed with liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) was proved as a feasible solution for exploring unknown bitter compounds. In this research, water-soluble particulate of cigarette smoke was separated by gel chromatography into several fractions, which were tasted by six experienced reviewers to orient the bitter fractions. Then the bitter fractions were combined to obtain bitter-characteristic component. Sixty-five compounds existing both in this component and in any bitter fraction were preliminarily found with Q-Exactive, a LC-HRMS instrument, using retention time and accurate molecular weight as filter. Sixteen structural formulas of these compounds were confirmed with LC-MS/MS, using retention time and secondary mass spectra of supposed standard substances as references. Finally the proved standard compounds were dissolved in water and tasted by six experienced reviewers. The result shows that ten bitter compounds in bitter-characteristic component were confirmed by more than half of them, which are anatabine, nornicotine, myosmine, cotinine, 2-n-butylimidazole, 2-isopropylimidazole,nicotinamide, N-methylnicotinamide, N-ethylnicotinamide and 3-ethyl-4-methyl-3-pyrrolin-2-one. This method is helpful to identify the key bitter ingredients of cigarette smoke, directionally design cigarette products so as to improve the sensory comfort. [ABSTRACT FROM AUTHOR]

Over many years, natural products have been a source of healing agents and have exhibited beneficial uses for treating human diseases. The Gentiana genus is the biggest genus in the Gentianaceae, with over 400 species distributed mainly in alpine zones of temperate countries around the world. Plants in the Gentiana genus have historically been used to treat a wide range of diseases. Still, only in the last years has particular attention been paid to the biological activities of Gentiana lutea Linn., also known as yellow Gentian or bitterwort. Several in vitro/vivo investigations and human interventional trials have demonstrated the promising activity of G. lutea extracts against oxidative stress, microbial infections, inflammation, obesity, atherosclerosis, etc.. A systematic approach was performed using Pubmed and Scopus databases to update G. lutea chemistry and activity. Specifically, this systematic review synthesized the major specialized bitter metabolites and the biological activity data obtained from different cell lines, animal models, and human interventional trials. This review aims to the exaltation of G. lutea as a source of bioactive compounds that can prevent and treat several human illnesses. [Display omitted] • Gentiana lutea L. as a great source of active molecules. • Bitter molecules from Gentiana lutea L. and their potential pharmacological uses. • A systematic overview of the healing properties of Gentiana lutea L. [ABSTRACT FROM AUTHOR]

The study produces white wines with the table grape (Guankou grape, Vitis vinifera × Vitis labrusca) using different pre-fermentation techniques to reduce bitterness and enhance aroma. Pre-fermentation techniques included pressing levels, low-temperature maceration, ultralow temperature freezing, hyperoxidation, and their different combinations. The compounds were analyzed by ultraperformance liquid chromatography (UPLC) and solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometric (GC-MS) analysis. The results shown that different pre-fermentation techniques influence the extraction of phenolic and aroma compounds, further forming different sensory qualities. The more damaging process increases the bitter phenols and unpleasant aroma compounds. Flavonoids, tartaric acid esters, and gallic acid esters caused bitterness, and 2,5-bis(1,1-dimethylethyl)-phenol mainly generated aromas of stone fruits. Finally, the results of the comprehensive evaluation of the sensory analysis suggested that after destemming and maceration (4 ± 1 °C, for 24 h), the most aromatic wines are fermented with pressed juice (pressure from 0.5 to 1.0 bar),and the most harmonious wines are fermented with free juice. The study provides a strong basis for winemaking with table grapes. [Display omitted] • Different pre-fermentation techniques influenced the extraction of fatty acids in the must and further affected the formation of esters in the fermentation. • A volatile phenol, 2,5-bis(1,1-dimethylethyl)-phenol, was detected in the Guankou wines, producing the aroma of stone fruit. • Although the hyper-oxidation treatment reduced the bitterness of the wine, it weakened the aromas and increased the methanol contents. • Processes of ultra-low temperature freezing and high-pressure pressing increased the contents of bitter phenols and geranyl acetone. • The content of low molecular mass flavanols and tartaric acid esters increased more than the other phenols during the maceration process. [ABSTRACT FROM AUTHOR]

Taste receptors are located on the epithelial surface throughout the alimentary canal to identify nutrients and potential toxins. In the oral cavity, the role of taste is to encourage or discourage ingestion, while in the gastrointestinal (GI) tract, the taste receptors help the body prepare for an appropriate response to the ingested foods. The GI sensing of bitter compounds may alter the secretion of appetite-related hormones thereby reducing food intake, which may have potential use for managing health outcomes. This systematic literature review investigated the acute effects of administering different bitter tasting compounds on circulating levels of selected GI hormones, subjective appetite, and energy intake in humans. A literature search was conducted using Medline, CINAHL and Web of Science databases. Of 290 articles identified, 16 met the inclusion criteria. Twelve studies assessed food intake; four of these found bitter administration decreased food intake and eight did not. Fourteen studies assessed subjective appetite; seven found bitter administration affected at least one measure of appetite and seven detected no significant changes. Nine studies included measures of GI hormones; no significant effects were found for changes in GLP-1, CCK or PYY. Four studies measured motilin and ghrelin and found mostly consistent changes in either food intake or subjective appetite. Overall, the data on food intake and subjective appetite were inconsistent, with only motilin and ghrelin responsive to post-oral bitter administration. There is limited consistent conclusive evidence that bitter compounds influence food intake, appetite or hormones with the reasons for this discussed within. SYSTEMATIC REVIEW REGISTRATION: CRD42021226102. [ABSTRACT FROM AUTHOR]