Role of bitter contributors and bitter taste receptors:a comprehensive review of their sources,functions and future development

Bitterness,one of the 5“basic tastes”,is usually undesired by humans.However,abundant literature reported that bitter fruits and vegetables have beneficial health effects due to their bitter contributors.This review provided an updated overview of the main bitter contributors of typical bitter fruits and vegetables and their health benefits.The main bitter contributors,including phenolics,terpenoids,alkaloids,amino acids,nucleosides and purines,were summarized.The bioactivities and wide range of beneficial effects of them on anti-cancers,anti-inflammations,anti-microbes,neuroprotection,inhibiting chronic and acute injury in organs,as well as regulating behavior performance and metabolism were reported.Furthermore,not only did the bitter taste receptors(taste receptor type 2 family,T2Rs)show taste effects,but extra-oral T2Rs could also be activated by binding with bitter components,regulating physiological activities via modulating hormone secretion,immunity,metabolism,and cell proliferation.This review provided a new perspective on exploring and explaining the nutrition of bitter foods,revealing the relationship between the functions of bitter contributors from food and T2Rs.Future trends may focus on revealing the possibility of T2Rs being targets for the treatment of diseases,exploring the mechanism of T2Rs mediating the bioactivities,and making bitter foods more acceptable without getting rid of bitter contributors.

Molecular mechanisms of bitterness and astringency in the oral cavity induced by soyasaponin

The interaction mechanism between soyasaponin(Ssa)and bitter receptors/mucin,as well as the saliva interface behavior of Ssa,were investigated to explore the presentation mechanism of Ssa bitterness and astringency(BA).Strong bitterness arising from high Ssa concentrations(0.5–1.5 mg/mL)had a masking effect on astringency.At Ssa concentrations of 1.0–1.5 mg/mL,Ssa micelles altered the structure of mucin,exposing its internal tryptophan to a more polar environment.At Ssa concentrations of 0.05–1.50 mg/mL,its reaction with mucin increased the aggregation of particles in artificial saliva,which reduced the frictional lubricating properties of oral saliva.Ssa-mucin interactions affected the salivary interfacial adsorption layer,and their complexes synergistically reduced the interfacial tension.Ssa monomers and soyasapogenols bind to bitter receptors/mucin via hydrogen bonding and hydrophobic interactions.Class A Ssa binds more strongly than class B Ssa,and thus likely presents a higher BA.In conclusion,Ssa interacts with bitter receptors/mucin causing conformational changes and aggregation of salivary mucin,resulting in diminished frictional lubricating properties of oral saliva.This,in turn,affects taste perception and gustatory transmission.

Emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate obtained by Corolase PP under high hydrostatic pressure

Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities.However,the problem related to the hydrolysis of proteins was the generation of the bitter taste.Recently,high hydrostatic pressure(HHP)treatment has attracted much interest and has been used in several studies on protein modification.Hence,the study aimed to investigate the effects of enzymatic hydrolysis by Corolase PP under different pressure treatments(0.1,100,200,and 300 MPa for 1-5 h at 50℃)on the emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate(SPIH).As observed,the hydrolysate obtained at 200 MPa for 4 h had the highest emulsifying activity index(47.49 m^(2)/g)and emulsifying stability index(92.98%),and it had higher antioxidant activities(44.77%DPPH free radical scavenging activity,31.12%superoxide anion radical scavenging activity,and 61.50%copper ion chelating activity).At the same time,the enhancement of emulsion stability was related to the increase of zeta potential and the decrease of mean particle size.In addition,the hydrolysate obtained at 200 MPa for 4 h had a lower bitterness value and showed better palatability.This study has a broad application prospect in developing food ingredients and healthy foods.

The role of the auxin-response genes MdGH3.1 and MdSAUR36 in bitter pit formation in apple

Apples often exhibit bitter pits in response to metabolic disorders during ripening and storage;however, the mechanisms underlying the bitter pit(BP) development remain unclear. Here, metabolome and transcriptome analyses were performed to investigate BP pulp of 'Fuji'. Two auxin-response genes, MdGH3.1 and MdSAUR36, were screened. Their expression as well as the auxin content in BP pulp were found to be higher than those in healthy pulp(P < 0.01). In the field, excess CO(NH2)2increased the incidence of BP. Moreover, the auxin content and MdGH3.1 expression increased in apples after nitrogen fertilization. On Day 30 before harvest, the two genes were transiently transferred to the fruit, and 20.69% and 23.21% of BP fruits were harvested. After 10 μmol·L-1auxin was infiltrated at low pressure into postharvest fruit, the increase in MdGH3.1 expression occurred earlier than that in MdSAUR36. MdGH3.1 increased the expression of MdSAUR36, but MdSAUR36 did not increase expression of MdGH3.1. Therefore, we suggest that MdGH3.1 acts upstream of MdSAUR36 during BP formation and that these genes induce BP formation by regulating auxin and phenylpropanoid biosynthesis.

A 1-bp deletion in the MC04g1399 is highly associated with failure to produce fruit wart in bitter gourd

Fruit wart is an important appearance trait influencing consumer preferences of bitter gourd(Momordica charantia L.).The molecular genetic mechanisms underlying fruit wart formation in bitter gourd are largely unknown.In this study,genetic analysis based on four generations showed that fruit wart formation in bitter gourd was controlled by a single dominant locus named as Fwa.The Fwa locus was initially mapped into a 4.82 Mb region on pseudochromosome 4 by BSA-seq analysis and subsequently narrowed down to a 286.30 kb region by linkage analysis.A large F2population consisting of 2360 individuals was used to screen recombinants,and the Fwa locus was finally fine mapped into a 22.70 kb region harboring four protein-coding genes through recombination analysis.MC04g1399,encoding an epidermal patterning factor 2-like protein,was proposed as the best candidate gene for Fwa via sequence variation and expression analysis.In addition,a 1-bp insertion and deletion(InDel)variation within MC04g1399 was converted to a cleaved amplified polymorphic sequence(CAPS)marker that could precisely distinguish between the warty and non-warty types with an accuracy rate of 100%among a wide panel of 126 bitter gourd germplasm resources.Our results not only provide a scientific basis for deciphering the molecular mechanisms underlying fruit wart formation but also provide a powerful tool for efficient genetic improvement of fruit wart via marker-assisted selection.

Analysis and Evaluation of Biochemical Components in Bitter Tea Plant Germplasms

Bitter tea is a special kind of tea germplasm in China.The major biochemical components of 24 bitter teas and other 8 Camellia sinensis var.sinensis and 8 C.sinensis var.assamica tea germplasms,which were stored in the China National Germplasm Hangzhou Tea Repository(CNGHTR),were analyzed and evaluated.The results showed that no significant differences of major biochemical components affecting the tea quality were found between bitter tea and common tea.According to the processing suitability index,bitter tea was suitable for the manufacturing of black tea;while according to evolutionary indices such as the composition and content of catechin,bitter tea was similar to C.sinensis var.assamica belonging to the relatively primitive type in evolution.The results of cluster analysis indicated that bitter tea was clustered with C.sinensis var.assamica,so it could be considered to belong to C.sinensis var.assamica.

Distribution of Calcium in Bagged Apple Fruit and Relationship between Antioxidant Enzyme Activity and Bitter Pit

[Objective]The aim was to study the distribution of Ca in bagged apple fruit and the relationship between antioxidant enzyme activity and bitter pit disease,which will provide a basis for resolving Ca metabolism disorder in apple cultivation. [Method]With Fuji Apple as the tested material,the changes of Ca2＋ content and antioxidant enzyme activity in different parts of apple fruit after picking bags and storage period were determined. [Result]The results showed that Ca contents in the light surface of fruits were higher than that in the backlight surface. The Ca contents of stalk cavity were higher than that of calyx-end. The activities of SOD,POD,CAT and APX in the light surface of fruits were higher than that in the backlight surface. The activities of SOD,POD,CAT and APX of stalk cavity were higher than that of calyx-end. The contents of MDA in the light surface of fruits were lower than that in the backlight surface. The contents of MDA of stalk cavity were lower than that of calyx-end. [Conclusion]The incidence rate of bitter pit in the light surface of fruits were lower than that in the backlight surface,and the incidence rate of bitter pit of stalk cavity were lower than that of calyx-end.

Study on Genetic Diversity of Agronomic Traits and Genetic Relationships among Core Collections of Bitter Gourd

[Objective] This study aimed to investigate the genetic diversity of agronomic traits and genetic relationships among core collections of bitter gourd.[Method] Total 141 germplasms of bitter gourd were selected,and the genetic diversity of 13 agronomic traits was analyzed.In addition,total 46 core collections of bitter gourd were employed,and their genetic relationships were analyzed based on the phenotypic values and genotypic values of 5 agronomic traits,respectively.[Result] The genetic diversity analysis of agronomic traits showed that the genetic diversity indexes of the 4 qualitative traits of bitter gourd germplasms ranged from 0.46 to 1.34;the distribution of the 9 quantitative traits data was more dispersed with average coefficient of variation of 20.02%.The genetic relationship analysis showed that based on the phenotypic values and genotypic values of the 5 quantitative traits,the genetic distances among the 46 core collections of bitter gourd were different.Based on the genotypic values,the genetic distances among the 46 bitter gourd core collections ranged from 0.84 to 10.71.The 46 germplasms were divided into 17 groups with the rescaled distance of 8.5,which further classified the relationships among different germplasms.[Conclusion] This study will lay a solid foundation for the effective utilization of core collections and new variety breeding in bitter gourd.

Effects of Controlled Release Nitrogen Fertilizer on Seedling Growth and Nutrient Uptake of Bitter Gourd

Different application rates of controlled release nitrogen fertilizer （CRFN） were designed to evaluate their effects on the growth and root morphology of bitter gourd （Momordica charantia L.） seedlings, and thus determine the optimal nitrogen amount and suitable nitrogen content in substrate at seedling transplanting,, in com- parison with conventional fertilizer application. CRFN was applied at five levels, 0, 0.6, 1.2, 2.4 and 4.8 kg N/m3, and conventional fertilizer was applied at 0.6 kg N/m3 as control. Four replicates were included in each treatment. The results showed that 0.6-2.4 kg N/m3 CRFN provided sufficient N nutrient for bitter gourd, with higher shoot and root dry weights, root length and root surface area than control treat- ments. Correspondingly, the total inorganic nitrogen in substrate ranged from 99.3 to 162.5 mg/pot at seedling transplanting in these treatments. 1.2 kg N/m3 was proven to be the optimal CRFN rate. Compared with conventional nitrogen fertilizer applica- tion, 1.2 kg N/m3 CRFN in substrate increased the dry weight, nitrogen uptake and improved root morphology indices of seedlings, and more than 83.3 mg/pot inorgan- ic nitrogen could be carried with substrate at transplanting, revealing a potential to reduce N-deficient risk after rain and basal N input by continuous release of CRFN.

Identification of Genetic Purity of Bitter Gourd Hybrid by ISSR Markers

Objective] This study was conducted to verify the feasibiIity of ISSR marker for identifying genetic purity of bitter gourd hybrid, and thus to provide an effective method for seed purity test in production practices. [Method] The DNA fin-gerprints of a bitter gourd cuItivar Xiuyu 1 and its parents were analyzed using IS-SR marker with 91 primers. [Result] Two primers ISSR-845 and ISSR-891 which ampIified two DNA bands of 510 and 300 bp respectiveIy from F1 generation and its parents were screened out from 91 primers. ISSR-845 couId distinguish the male parent from F1 hybrid and the female parent, whiIe ISSR-891 couId distinguish the female parent inbred Iine from Xiuyu 1. Seed purity test with the specific markers gave the same resuIt with fiIed trials based on morphoIogical identification. [Conclu-sion] ISSR marker is an accurate, simpIe and effective method for seed purity test bitter gourd hybrid, and thus can be used in production practices.

A NOVEL BITTER DETECTION BIOSENSOR BASED ON LIGHT ADDRESSABLE POTENTIOMETRIC SENSOR

This paper presents a novel biosensor for bitter substance detection on the basis of light addressable potentiometric sensor(LAPS).Taste receptor cells(TRCs)were used as sensitive elements,which can respond to different bitter stimuli with extreme high sensitivity and speci-ficity.TRCs were isolated from the taste buds of rats and cultured on the surface of LAPS chip.Due to the unique advantages such as single-cell recording,light addressable capability,and noninvasiveness,LAPS chip was used as secondary transducer to monitor the responses of TRCs by recording extracelluar potential changes.The results indicate LAPS chip can effectively record the responses of TRCs to different bitter substances used in this study in a real-time manner for a long-term.In addition,by performing principal component analysis on the LAPS recording data,different bitter substances tested can be successfully discriminated.It is suggested this TRCs
LAPS hybrid biosensor could be a valuable tool for bitter substance detection.With further improvement and novel design,it has great potentials to be applied in both basic research and practical applications related to bitter taste detection.

Discovery of the relationship between bitter taste and bitter flavor (efficacy) based on hTAS2Rs

Objective:To explore the relationship between bitter taste and bitter flavor(efficacy),their character-istics were analyzed at the target and pharmacodynamic points.Methods:Compounds with bitter receptor activity were obtained by high-throughput screening models of the human bitter taste receptors(hTAS2Rs),which were used to analyze bitter taste.The efficacy of anti-asthma medications was used as an example to research bitter flavor(efficacy).The pharmacological effects of bitter taste and bitter flavor(efficacy)were classified according to the functional modules.The coverage for the same targets or pharmacological effects in the overall protein interaction network(PIN)of bitter taste and bitter flavor(efficacy)was analyzed to reveal their relationship.The effect of the compound polydatin with anti-asthma activation on hTAS2R14 was studied to verify the reliability of the aforementioned idea.Results:A total of 121 Chinese materia medica(CMM)compounds that activate hTAS2R10,hTAS2R14,and hTAS2R49 were obtained.The analysis results indicated that 108 same targets for bitter taste and bitter flavor(efficacy)were obtained,accounting for 13.9%in the PIN of bitter taste and 72.5%in the PIN of bitter flavor(efficacy).The pharmacological effects shared by bitter taste and bitter flavor(efficacy)accounted for 79%of the PIN of bitter taste and 81%of the PIN of bitter flavor(efficacy).The activating effect of the anti-asthma compound polydatin on hTAS2R14 was dose-dependent with EC 50 of 4.3 m M.Conclusion:In this study,the relationship between bitter taste and bitter flavor(efficacy)has been demonstrated from the target and pharmacodynamic points,which are based on hTAS2Rs and anti-asthma effect.Bitter taste and bitter flavor(efficacy)exhibited a high correlation.This study provides a theoretical and scientific basis for the hypothesis that“the property theory of CMM is the clinical pharmacodynamics of CMM.”

Bitter型环向场线圈电流分布的研究

本文简述了用数值方法研究Ｂｉｔｔｅｒ型环向场线圈中电流分布情况，给出了不同时刻线圈中电流分布的形式以及线圈电感、电阻随时间的变化．也对电磁力的分布作了分析。

Evaluation of Bitterness Intensity of Citrus Products by an Untrained Panel Using Relative-to-Reference Rating

In order to estimate the bitterness intensity of citrus products we applied an adaptative sensory evaluation method, using naringin as the reference for bitterness. Twenty-five untrained subjects participated in this study. Firstly they tasted and positioned 2 naringin references on an unstructured relative-to-reference scaling to define their own bitterness scales. They then evaluated the bitterness intensity of 2 types of bitter orange products (3 distillates and 2 cold-pressed essential oils of bitter orange peels) according to their own perceptions on their own scales. We observed that 2 types of scale use could be distinguished that might be related to subjects’ sensitivity or/and consumption habits to bitterness. As a result, we observed a significant difference in bitterness intensity between the crude cold-pressed essential oil and the debittered one of bitter orange, whereas there was no significant difference between the 3 distillates. This approach makes it possible to take inter-individual differences in subjects’ sensitivity into account. It also provides a way to very simply rate bitterness intensity with subjects who have received no prior training in sensory evaluation.

Enzymatic Hydrolysis of Defatted Mackerel Protein with Low Bitter Taste

Ultrasound-assisted solvent extraction was confirmed as a novel,effective method for separating lipid from mackerel pro-tein,resulting in a degreasing rate (DR) of 95% and a nitrogen recovery (NR) of 88.6%.To obtain protein hydrolysates with high ni-trogen recovery and low bitter taste,enzymatic hydrolysis was performed using eight commercially available proteases.It turned out that the optimum enzyme was the ‘Mixed enzymes for animal proteolysis’.An enzyme dosage of 4%,a temperature of 50℃,and a hydrolysis time of 300 min were found to be the optimum conditions to obtain high NR (84.28%) and degree of hydrolysis (DH,16.18%) by orthogonal experiments.Glutamic acid was the most abundant amino acid of MDP (defatted mackerel protein) and MDPH (defatted mackerel protein hydrolysates).Compared with the FAO/WHO reference protein,the essential amino acid chemical scores (CS) were greater than 1.0 (1.0 1.7) in MDPH,which is reflective of high nutritional value.This,coupled with the light color and slight fishy odor,indicates that MDPH would potentially have a wide range of applications such as nutritional additives,functional ingredients,and so on.

Anticariogenic potentials of clove,tobacco and bitter kola

Objective:To investigate three tropical plant materials - clove seeds[Syzygium aromalicum(S. aromaticum)],bitter kola fruits[Garcinia kola(G.kola)]and tobacco leaves(Nicotiana species) as potential targeted killers of Streptococcus mutans(S.mutatis),a cavity-causing bacterium(gram-positive, facultative anaerobe) that resides in a multispecies microbial community(dental plaque) for the treatment of dental caries(tooth decay).Methods:Thirty one(31) teeth samples were collected from patients with obvious signs of tooth decay(swollen gum,weak or fallen tooth,etc.) using sterile swab sticks.These samples were collected from two major denial clinics in Nsukka, Enugu State,Nigeria and investigated by spread inoculation onto sterile blood agar and Mueller Hinton agar(MHA) respectively and incubated at 37℃for 24 h.The discrete colonies obtained were further re-inoculated onto sterile Mitis salivarius agar(MSA) plates and incubated as above. The isolates were characterized by gram staining and calalase lesl.Tobacco leaves,clove seeds and bitter kola fruits were ground into powder,extracted with three different solvents(n-hexane, hot water and ethanol),filtered,dried and stored in clean containers,corked and kept until used. The plant extracts were investigated for phytochemistry,minimum inhibitory concentration(MIC), minimum cidal concentration(MCC)and compared with some conventional antibiotics commonly used against tooth decay.Antibiotic sensitivity test was also carried out.The results were statistically analyzed.Results:The extracts showed varied phytochemical composition but most abundantly the flavonoids.Our result also shows that females(16) have more tooth decay than males(15) and that 16 samples were very bloody while 15 were slightly bloody.The microbial characterization showed that 18 samples were catalase-positive indicating the presence of S. mutans while 13 were catalase-negative suspected to be Staphylococcus spp.The Gram reaction confirmed 13 Gram-negative and 18 Gram-positive organisms.The n-hexane extract had the best antimicrobial activity followed by the ethanol and lastly hot water.MIC showed that n-hexane clove extract had the largest inhibition zone diameter,followed by bitter kola extract and lastly tobacco extract.The antibiotic sensitivity test credited ciprofloxacin the best because it exhibited broad spectrum of action.Conclusions:Since the n-hexane extract of clove seeds demonstrated preferential growth-inhibitory activity against the causal cariogenic pathogens(S.mutans) in dental caries,we therefore,report here that clove extract be henceforth considered as a potential ingredient in toothpaste preparation.

Extraction of Flavonoids from Bitter Melon

Bitter melon, Momordica charantia L, is a popular traditional medicinal fruit in tropical and subtropical countries. It has been linked with therapeutic effects, some of which are likely due to its flavonoids. To determine its total flavonoid content (TFC) and to prepare extracts for use as nutritional supplements or ingredients for nutraceutical functional foods, various solvents have been used, including water, which is the preferred solvent because it is inexpensive, safe and environmentally friendly. The study aimed to extract bitter melon, using five solvents (ethanol, methanol, n-butanol, acetone and water) before and after the optimal conditions for water were determined in terms of extraction temperature, time, ratio of water to bitter melon (mL/g) and number of times the same material was extracted. The TFC of six varieties of bitter melon was also determined. Acetone was the best of the five solvents for extracting flavonoids from the Moonlight variety (23.2 mg Rutin Equivalents (RE)/g). Even after increasing the extraction by 88% (1.24 vs 0.66 mg RE/g) using optimised conditions for the aqueous extraction (two extractions at 40℃ for 15 min at a ratio of 100:1 mL/g of bitter melon powder), the flavonoids extracted from the Moonlight variety using water was very little (5.4%) compared to acetone. Furthermore, using acetone, it was shown that the Moonlight variety (23.2 mg RE/g) bought at a local market had higher levels of flavonoids than the greenhouse-grown Jade (15.3 mg RE/g), Niddhi (16.9 mg RE/g), Indra (15.0 mg RE/ g), Hanuman (3.9 mg RE/g) and White (6.9 mg RE/g) varieties. Therefore, acetone was the best solvent for extracting flavonoids from bitter melon and the aqueous extraction could only be improved to extract 5.4% of the flavonoids extracted with acetone from the Moonlight variety, which had the highest TFC of the six varieties of bitter melon.

Isolation and Identification of Fusarium Wilt Pathogens from Bitter Gourd in Hainan Province

In order to isolate and identify the pathogens causing Fusarium wilt in bitter gourd in Hainan Province, China, four bitter gourd plants exhibiting symptoms of Fusarium wilt were collected from Tunchang County, Hainan Province. Four pathogen strains （HNTC-01, HNTC-02, HNTC-03 and HNTC-04） were isolated from the four plants, and identified via morphological observation and molecular techniques. The results showed that HNTC--01, HNTC-03 and HNTC-04 were F. oxysporum, while HNTC-02 was F. graminearum. The tests on pathogenicity and host specificity showed that HNTC-01, HNTC-03 and HNTC-04 were F. oxysporum Schl. f. sp. momordicae. Phylogenetic analysis revealed that HNTC-01, HNTC-03, HNTC-04 were clustered together with 14 strains of F. oxysporum, and HNTC-02 was clustered together with six strains of F. graminearum. In addition, rDNA-ITS region can be used to distinguish different Fusarium species, but can not be used to distinguish different biotypes within a Fusarium species. This study could provide a scientific basis for the diagnosis and prevention of wilt in bitter gourd.

Comparison of antioxidant capacity and α-glucosidase inhibitory activity between bitter melon(Momardica charanti) fruit and leaf extract

Objective:To compare the physiologically active substances,antioxidant and anti diabetic activities in vitro of bitter melon fruit and leaf extract.Methods:Total polyphenol and flavonoid contents were measured using spectrophotometrically by gallic acid and catechin standard curves,respectively.The radical-scavenging potential of bitter melon fruit and leaf extract were measured by DPPH,ABTS and hydroxyl radical scavenging ability and reducing power and anti-diabetic ability was evaluated byα-glucosidase activity.Results:It was confirmed that the bitter melon leaf contained more total polyphenols and flavonoidsthan bitter melon fruits.Bitter melon leaf extract contained 2.8-fold and 4.9-fold higher total polyphenols and flavonoids than bitter melon fruits,respectively.The DPPH radical scavenging activity of bitter melon leaf was 5.81-and 5.70-fold higherthan that of the bitter melon frui,based on200μg/mL and 400μg/mL of the extract,respectively.In ABTS,hydroxyl radical scavenging ability and reducing power,the bitter melon leaf extract all showed higher antioxidant capacity than the bitter melon fruit.Bitter melon fruit showed 2.52-and 2.63-fold higherα-glucosidase inhibitory activity than bitter melon leaf extract at 200μg/mL and 400μg/mL,respectively.Conclusions:Based on our results,bitter melon may improve antidiabetic effects by upreguatingα-glycosidase activity.Even,bitter melon leaf extract shows higher antioxidant potential than its fruit but bitter melon leaf extract does not show higherα-glucosidase inhibitory potential than bitter melon fruit.The overall results support that bitter melon fruit and leaf may have specific torget effects on antidiabetic and antioxidant,respectively.

基于框架语义理论的“bitter”和“苦”的认知对比研究

运用框架语义理论对比研究"bitter"和"苦",发现二者之间存在大同小异的关系。认为二者拥有味觉、视觉、心理感知和经历四种共同的语义框架。疾病框架和宗教框架是汉语"苦"所特有的,且通过心理感知框架隐喻映射到经历、心智和程度框架;bitter所特有的是能够通过心理感知框架转喻映射到情感、斗争和天气框架。