• Korean journal of food and cookery science
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• v.12 no.1
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• pp.115-121
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• 1996

Ixeris dentata Nakai (Compositae) is a perennial herb and the young shoots when prepared properly are edible as a bitter appetizing vegetable in the early spring. The whole plant has been used as a folk medicine in treating diabetes in Korea. As a part of our studies on bitter substances, we have investigated the bitterness of the plant through a taste-guided fractionation method. Bitter substances were extracted by the solvent fractionation and the bitterness was evaluated by 10 trained panelists consisted with graduate students of Dept. of Foods and Nutrition. It has been revealed that the bitter compounds were distributed throughout the extracting fractions and the higher intensity of the bitterness was seen in the n-BuOH fractions. The bitter compounds were subfractionated by the silica gel column chromatography and the bitterness was evaluated by the trained panelists. The subfractions which were indicated as the bitter compounds will be further studied to isolate the compounds. The H$_2$O fractions were grouped according to the molecular weight through the ultrafiltration and the group with 1,000 < m.w. < 30,000 was evaluated as the most intense bitter subfraction.

• Preventive Nutrition and Food Science
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• v.22 no.2
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• pp.107-117
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• 2017

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce $FeCl_3$ solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical ($DPPH^{\cdot}$) scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation ($ABTS^{{\cdot}+}$) scavenging activity, nitric oxide radical ($NO^{\cdot}$) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit $Fe^{2+}$-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, $DPPH^{\cdot}$ scavenging activity, $ABTS^{{\cdot}+}$ scavenging activity, and $NO^{\cdot}$ scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.1
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• pp.72-75
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• 2018

This study was conducted to investigate changes in the functional compounds in bitter gourd (Momordica charantia L.). Four treatments were used to analyze vitamin C, momordicin, K, Mg, and Ca compounds in Dragon bitter gourd on the 7th, 14th, 21st, and 28th days after pollination. According to the number of days after pollination, level of chemicals containing vitamin C in bitter gourd appeared to decrease continually after pollination, and was the highest, being 74.7 mg/100 g on the 7th day. The level of momordicin, an anti-diabetic was significantly higher in the 7th-day product than that of the 14th day;, meanwhile, there was no significant difference in Ca compounds. These phenomena are considered to fasten the stages of harvest for effective use of functional ingredients in bitter gourd fruits.

• Food Science and Preservation
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• v.30 no.4
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• pp.663-668
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• 2023

Ginseng root is a medicinal plant widely used in Korea for its immunity enhancing and anti-fatigue properties. However, its bitter taste has a negative impact on the expansion of the ginseng market. In this study, we determined the bitter tasting compounds of ginseng using an electronic tongue. The results of measuring bitterness showed that phenolic compounds and polyacetylenes of ginseng had low bitterness. On the other hand, the bitterness was strong in ginsenosides and alkaloids of ginseng. Among them, the bitterness of ginseng was higher in ginsenosides than in alkaloids. Theses results suggest that ginsenosides have a significant affect on the bitter taste of ginseng.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.319-325
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• 1999

Volatile flavor compounds in Korean salt fermented shrimp on the market were analyzed by vacuum simultaneous distillation solvent extraction/gas chromatography/mass spectrometry/olfac tometry(V SDE/GC/MS/O) and aroma extract dilution anlaysis(AEDA). A total of 32 volatile com pounds were detected by GC/O analysis. Of these, 18 were positively identified, and composed of S containing compounds(5), aldehydes(4), ketones(3), N containing compounds(3), ester(1), alcohol(1) and aromatic hydrocarbon(1). Predominant odorants(Log3FD$\geq$4) in salt fermented shrimp were 2,3 butanedione(sour/buttery), 1 octen 3 one(earthy/mushroom like), dimethyl trisulfide(cooked cabbage /soy sauce like) and 2 acetylthiazole(grainy/nutty). Predominant free amino acids were aspartic acid, glutamic acid(sour and umami taste), arginine, methionine(bitter) and lysine(sweet and bitter) in evaluation of taste value.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.98-104
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• 1995

Five bitter taste compounds (OY-22, OY-23, OY-24, OY-25 and OY-26) were firstly isolated from cultured oyster (Crassostrea gigas) at Gamak Bay, Sourthern coast of Korea, between November, 1989 and January, 1990, and smoked-canned oyster, which were produced by the same oysters. They were presumed as cyclic peptides composed with 6 or 7 amino acids, including sulfur on the basis of NMR and MS spectra. Val and Leu in OY-24, leu and lie in OY-25 and tow leucines in OY-26 were detected from those each compounds, seperately, by the amino acid analysis. Another amino acids were thought as non-constitutional amino acids. They showed non-toxic to mice $(100{\mu}g/20g\;mice i.p.)$ and non actibacterial artivities to Asp. niger and B. subtilis $(10{\mu}g/disk)$. The chemical structures and other biological activities of them are now in studying.

• Journal of Life Science
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• v.18 no.7
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• pp.1011-1014
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• 2008

The ability or inability to taste phenylthiocarbamide (PTC) is a classic inherited trait that has been best-studied in human populations. Also, variation in PTC perception has been correlated with dietary preferences and thus may have important consequence for diet-related diseases in modem populations. The recent identification of the TAS2R38 gene (PTC gene) which is a member of TAS2R family of bitter taste receptor genes and three common polymorphisms in the gene is highly correlated with taste sensitivity to PTC. Balancing natural selection has acted to maintain high frequency of both alleles of the gene in human population. Future detailed studies of the relationships between molecular mechanisms and taste function may have therapeutic implications, such as helping patients to consume beneficial bitter-tasting compounds.

• Molecules and Cells
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• v.46 no.7
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• pp.451-460
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• 2023

Animals generally prefer nutrients and avoid toxic and harmful chemicals. Recent behavioral and physiological studies have identified that sweet-sensing gustatory receptor neurons (GRNs) in Drosophila melanogaster mediate appetitive behaviors toward fatty acids. Sweet-sensing GRN activation requires the function of the ionotropic receptors IR25a, IR56d, and IR76b, as well as the gustatory receptor GR64e. However, we reveal that hexanoic acid (HA) is toxic rather than nutritious to D. melanogaster. HA is one of the major components of the fruit Morinda citrifolia (noni). Thus, we analyzed the gustatory responses to one of major noni fatty acids, HA, via electrophysiology and proboscis extension response (PER) assay. Electrophysiological tests show this is reminiscent of arginine-mediated neuronal responses. Here, we determined that a low concentration of HA induced attraction, which was mediated by sweet-sensing GRNs, and a high concentration of HA induced aversion, which was mediated by bitter-sensing GRNs. We also demonstrated that a low concentration of HA elicits attraction mainly mediated by GR64d and IR56d expressed by sweet-sensing GRNs, but a high concentration of HA activates three gustatory receptors (GR32a, GR33a, and GR66a) expressed by bitter-sensing GRNs. The mechanism of sensing HA is biphasic in a dose dependent manner. Furthermore, HA inhibit sugar-mediated activation like other bitter compounds. Taken together, we discovered a binary HA-sensing mechanism that may be evolutionarily meaningful in the foraging niche of insects.

• Proceedings of the Korea Hospitality Industry Research Society Conference
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• 2003.05a
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• pp.19-35
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• 2003

This study was carried out to find a cholesterol removal rate, flavor development, and bitter amino acid productions in Cheddar cheese treated with -cyclodextrin (${\beta}-CD$): 1) Control (no homogenization, no ${\beta}--CD$), and 2) Milk treatment (1000 psi milk homogenization, 1% ${\beta}-CD$). The cholesterol removal of the cheese were 79.3%. The production of short-chain free fatty acids (FFA) increased with a ripening time in both control and milk treated cheese. The releasing quantity of short-chain FFA was higher din milk treated cheese than control at 5 and 7 mo ripening. Not much difference was found in neutral volatile compounds production between samples. In bitter-tasted amino acids, milk treatment group produced much higher than control. In sensory analysis, texture score of control Cheddar cheese significantly increased, however, that in cholesterol-reduced cheese decreased dramatically with ripening time.

• International Journal of Oral Biology
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• v.43 no.1
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• pp.5-11
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• 2018

Recent findings indicate that Type 2 taste receptors (T2Rs) are expressed outside the gustatory system, including in the gastrointestinal tracts and the exocrine glands, such as the submandibular (SM), parotid (P), lacrimal (L) glands and pancreas (PC). Specifically, T2Rs are found in some of the gastrointestinal endocrine cells, and these cells secreted peptide hormones in response to stimulation by bitter-tasting compounds. The results show that T2Rs may have significant physiological roles besides bitter taste reception. The functions of the T2Rs in the exocrine glands remain poorly understood. An expression levels analysis of T2Rs will help to determine those functions in the exocrine glands. The expression levels of the T2Rs in the exocrine glands were discovered via the qPCR. C57BL/6J mice of 42~60-day-old were used. Messenger RNAs were extracted from S, P, L and PC. Cloned DNAs were synthesized by reverse transcription. Quantitative PCRs were performed using the SYBR Green method. The expression levels of the T2Rs were calculated as relative expression levels to that of the GAPDH. The statistical significance among the observed exocrine glands was tested using the variance analysis (ANOVA test). Tas2r108, out of murine 35 T2Rs, was the most highly expressed in every observed exocrine gland. This finding was similar to previous results from tongue papillae, but the expression levels were lower than those of the tongue papillae. Tas2r137 of SM, P, L and PC were expressed a little lower than that of tongue papillae. The T2Rs in the exocrine glands may play slightly different roles from those in the tongue. We suggest that physiological studies such as a patch clamp and functional $Ca^{2+}$ imaging of acinar cells are necessary for understanding the Tas2r108 functions.