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We have developed laser desorption ionization mass spectrometry (LDI-MS) of organic molecules encapsulated in a crystalline sponge (CS). Cyclic organic compounds 1,2,3,4,5-pentamethylcyclopentadiene, zerumbone, and muscone were encapsulated in CS as guest regardless of guest crystallization. Single-crystal X-ray analysis closely scrutinized the position of the guest in the pore and the interaction between the guest and the CS framework. After single-crystal X-ray analysis, the same single crystal was subjected to LDI-MS. Ionization efficiency differed markedly depending on whether π−π interaction existed or not. It is obvious that π−π interaction is the key to transferring laser energy from the CS framework to the guest for the ionization of molecule encapsulated in CS. The results suggest the importance of controlling the positions of analyte and matrix as well as noncovalent interactions, such as hydrogen bonding interaction, electrostatic interaction, and so on.

Some components of bitterness make key flavor contributions to promote the palatability of foods, whereas other components are recognized as aversive signals to avoid consuming harmful substances. These contradictory behaviors suggest that humans tolerate tastes of bitterants based on certain criteria. Here, we investigated human taste tolerance and sensory cues leading to diverse taste tolerance of bitter compounds. Tolerance of eight bitter compounds, which are typically contained in foods, was evaluated by measuring detection and rejection thresholds. The results revealed that the level of tolerance of each compound was variable, and some compounds showed an acceptable concentration regarding the suprathreshold intensity. Tolerance did not depend on the nutritive value or attenuation and accumulation characteristics of bitterness and bitter taste receptors. These results suggest that the criteria controlling tolerance of bitter compounds may be derived from a complex relationship between the taste quality and cognitive process.

Soybeans (Glycine max (L,) Merr,) contain γ-glutamyl peptides and oligosaccharides, and these components play an important role in imparting the “kokumi” taste to foods. To gain insight into the genetic diversities and molecular mechanisms of accumulation of γ-glutamyl peptides and oligosaccharides in soybean, we measured the contents of these components using the Japan and World mini core collections. Similar to other previously reported traits, wide variations were detected among the accessions in the core collections with respect to the content of γ-glutamyl peptides and oligosaccharides. We found a positive relationship between the content of γ-glutamyl tyrosine and γ-glutamyl phenylalanine and between the content of raffinose and stachyose. Furthermore, there were unique accessions that included high levels of γ-glutamyl peptides and oligosaccharides. These accessions may be helpful in understanding the accumulation mechanism of γ-glutamyl peptides and oligosaccharides and to increase the “kokumi” taste components in soybean by performing a genetic analysis.

The crystalline sponge (CS) method, which employs single-crystal X-ray diffraction to determine the structure of an analyte present as a liquid or an oil and having a low melting point, was used in combination with laser desorption ionization mass spectrometry (LDI-MS). 1,3-Benzodioxole derivatives were encapsulated in CS and their structures were determined by combining X-ray crystallography and MS. After the X-ray analysis, the CS was subjected to imaging mass spectrometry (IMS) with an LDI spiral-time-of-flight mass spectrometer (TOF-MS). The ion detection area matched the microscopic image of the encapsulated CS. In addition, the accumulated 1D mass spectra showed that fragmentation of the guest molecule (hereafter, guest) can be easily visualized without any interference from the fragment ions of CS except for two strong ion peaks derived from the tridentate ligand TPT (2,4,6-tris(4-pyridyl)-1,3,5-triazine) of the CS and its fragment. X-ray analysis clearly showed the presence of the guest as well as the π-π, CH-halogen, and CH-O interactions between the guest and the CS framework. However, some guests remained randomly diffused in the nanopores of CS. In addition, the detection limit was less than sub-pmol order based on the weight and density of CS determined by X-ray analysis. Spectroscopic data, such as UV-vis and NMR, also supported the encapsulation of the guest through the interaction between the guest and CS components. The results denote that the CS-LDI-MS method, which combines CS, X-ray analysis and LDI-MS, is effective for structure determination.

The aim of this study was to analyze changes in the surface structure and the inner microstructure of durum wheat pasta during the boiling process. Dried pasta was boiled for 1, 4, 7, or 10 min, and the structure of dried and boiled pasta was observed using polarizing light, laser, and fluorescence microscopy. The degree of gelatinization was measured by polarized light microscopy as well as the β-amylase-pullulanase method. The degree of gelatinization was shown to be larger when evaluated by polarized light microscopy. The surface roughness was evaluated by laser microscopy. The surface roughnesses of dried (non-boiled) pasta and boiled pasta showed different characteristics, and the calculation and analysis of parameters relating to surface roughness indicated that the surface of pasta becomes more uneven as boiling time increases. In principal component analysis of surface roughness, principal components 1 and 2 explained 71.7% of total variance. Principal component 1 mainly reflected the peak frequency and height, and principal component 2 mainly reflected the peak interval. We confirmed by fluorescence microscopy that starch granules began to swell from the outer periphery of the pasta during boiling, and the proportion of gluten network on the outer circumference structure clearly decreased.

1,3-Oxazepines are of interest because of their application as biologically active substances. Herein, 2′-amino-2-hydroxybiphenyl was reacted with isothiocyanate-derived thioureas and treated in situ with iodine in the presence of triethylamine to afford dibenzo[d,f][1,3]oxazepine derivatives in good-to-excellent yields. X-ray analysis revealed that the obtained product comprises a 7-membered heterocycle and has a Z-configuration imine moiety in its solid state. All oxazepine derivatives obtained by this reaction are novel compounds.

The water extract of soybean seeds (Glycine max (L.) Merr.) is nearly tasteless, but “kokumi” taste sensation was confirmed upon addition of a basic umami solution containing glutamic acid, inosine monophosphate, and sodium chloride. To identify the key contributors to the “kokumi” taste sensation in soybean seeds, sensory-guided fractionation, taste sensory analyses, and LC–MS/MS analyses were utilized. γ-glutamyl-tyrosine and γ-glutamyl-phenylalanine were identified as contributors to “kokumi taste”; specifically, these γ-glutamyl peptides imparted the “kokumi” taste sensation at a low taste threshold in a basic umami solution. Raffinose and stachyose, which are sufficiently present in soybean seeds, exhibited a synergistic effect in regard to the enhanced “kokumi” taste sensation of γ-glutamyl peptides. This is the first report that the combined use of γ-glutamyl peptides and oligosaccharides can increase the “kokumi” intensity, which suggests that soybean extracts or soymilk can be used to enhance the “kokumi” taste sensation in food products.

The Pd-catalyzed cross-coupling reactions of Sb-aryl-1,5-azastibocines with alkenes are described. The reactions of azastibocines with alkenes such as vinyl ketones, alkenes, and acrylates in the presence of 10 mol% PdCl2 at 80 °C in DMA under aerobic conditions produced Heck adducts in moderate-to-excellent yields. Single-crystal X-ray and NMR analysis revealed that the aryl donors in this reaction, the Sb-aryl-1,5-azastibocines, are hypervalent compounds that display N–Sb intramolecular non-bonding interaction. These are the first examples of Pd-catalyzed Heck-type arylations using heterocyclic hypervalent organoantimony compounds. Although the reactions proceeded efficiently with the azastibocines, they hardly progressed with trivalent and pentavalent triarylantimony reagents.

Tolerance to bitter foods and its potentiation by repetitive exposure are commonly experienced and potentially underlie the consumption of bitter foods, but it remains unknown whether permissive and adaptive responses are general phenomena for bitter-tasting substances or specific to certain substances, and they have not been rigorously studied in mice. Here, we investigated the effects of prolonged exposure to a bitter compound on both recognition and rejection behaviors to the same compound in mice. Paired measurements of rejection (RjT) and apparent recognition (aRcT) thresholds were conducted using brief-access two-bottle choice tests before and after taste aversion conditioning, respectively. First, RjT was much higher than aRcT for the bitter amino acids L-tryptophan and L-isoleucine, which mice taste daily in their food, indicating strong acceptance of those familiar stimuli within the concentration range between RjT and aRcT. Next, we tested five other structurally dissimilar bitter compounds, to which mice were naive at the beginning of experiments: denatonium benzoate, quinine-HCl, caffeine, salicin, and epigallocatechin gallate. RjT was moderately higher than aRcT for all the compounds tested, indicating the presence of innate acceptance to these various, unfamiliar bitter stimuli in mice. Lastly, a 3-week forced exposure increased RjT for all the bitter compounds except salicin, demonstrating that mice acquire tolerance to a broad array of bitter compounds after long-term exposure to them. Although the underlying mechanisms remain to be determined, our studies provide behavioral evidence of innate and acquired tolerance to various bitter stimuli in mice, suggesting its generality among bitterants.

Food contains various taste substances. Among them, umami substances play an important role with regard to the perception of the taste of food, but, few studies have examined the taste characteristics of representative umami substances other than monosodium L-glutamate (MSG). By conducting mouse behavioral studies (the 48-h 2-bottle preference test and the conditioned taste aversion test) and assessing gustatory nerve responses, we investigated the taste characteristics of unique umami substances, including sodium succinate, L-theanine, betaine, and the enantiomer of MSG, D-MSG. Furthermore, we examined the synergy of umami with inosine 5'-monophoshate (IMP). In the case of the mice, sodium succinate had an umami taste and showed strong synergy with IMP. L-theanine showed synergy with IMP but did not have an umami taste without IMP. In contrast, betaine did not have an umami taste or synergy with IMP. D-MSG might have weak synergy with IMP.

Theanine is a unique amino acid present in green tea. It is partly responsible for the taste of green tea and possesses various psychological effects. Theanine has a preferred taste, like umami and sweetness. Therefore, theanine may improve unpleasant tastes such as bitterness and sourness of foods. To investigate new uses of theanine, we investigated its taste-modifying effect by human sensory evaluation. A reduction in sourness was observed with theanine addition. Investigation of the mechanism of taste improvement found that sourness is relatively improved by theanine addition due to the increase in pH and the addition of the umami taste.

In order to determine the influence of prolonged exercise on sensitivity to sweet taste, we investigated the relationship between physical fatigue and palatability and/or taste intensity by performing sensory evaluation tests. The subjects hiked up a 36-km mountain trail for 12 h, and we used 100- and 300-mM sucrose solutions as test samples. The taste intensity and palatability of the sucrose solutions did not change significantly during exercise. However, a slight change in palatability was observed. In particular, the palatability of the 300-mM solution increased with an increase in the degree of physical fatigue towards the end of the exercise.

Many athletes experience a change in taste sensitivity due to physical fatigue. Nutrition is an important factor during training and recovery. Previous reports have described the ideal alimentation for athletes, however, the alimentation appropriate for physical fatigue has not been investigated. As a part of gustation research aimed at formulating an ideal alimentation for fatigue, we investigated the relationship between fatigue and taste sensitivity to sweet substances. Athletes were asked to perform a half marathon to induce physical fatigue. We used a triangle test to determine the detection threshold for sucrose solutions before and after running. The results revealed that the threshold decreased after the half marathon. Thus, we confirmed that taste sensitivity to sweetness increased as a consequence of physical fatigue. To avoid either a lack or excess in nutrient intake during post-exercise physical fatigue, an alimentation regime that takes into consideration this change in taste sense is necessary.

誘導結合型プラズマ質量分析法（ICP-MS），誘導結合型プラズマ発光分析法（ICP-AES）を利用した下水汚泥中多元素定量法を開発した．試料の溶液化はマイクロ波酸分解法又はアルカリ融解法で行い，元素測定にはICP-MS及びICP-AESを用いた．分析値の評価には，Institute for Reference Materials and Measurements（ヨーロッパ共同体標準物質計測研究所，IRMM）より頒布されている下水汚泥標準物質（BCR-144R）を使用した．アルカリ融解法では，Zn，Cu，Pb，Ni，Co，Cdで保証値より定量値が低くなった．この濃度低下はZn，Pb，CoとCdでは揮発，Cu及びNiではPtるつぼへの合金形成が主な要因であることが分かった．また，Nb，Ta，Hfの溶解にはマイクロ波酸分解法及びアルカリ融解法双方において溶解液へのフッ化水素酸の添加が必要であった．そこで，徳島市で採取した下水汚泥実試料をマイクロ波酸分解/ICP-MS，ICP-AES法により分析した結果，計44元素の定量が可能であった．

Al-doped In2O3-ZnO films were developed and the influence of Al doping in electrical and optical properties of In2O3-ZnO films was investigated. Amorphous and homologous phases appeared with increasing δ=Zn∕(Zn+In) ratios. The carrier generation mechanism is discussed for these films. Native oxygen defects are the primary donors for the In2O3-ZnO films. Then the low resistivities of 2–4×10−4Ωcm were attained within a narrow range of δ=Zn∕(Zn+In) in the amorphous phase film. Two wt % (percent by weight) Al2O3-doping decreased the resistivity to 1.5–2.1×10−4Ωcm. At doping of 3 and 4 wt % Al2O3, film resistivities of 2–4×10−4Ωcm were attained for a relatively wide range of δ in the amorphous phase due to an increase in carrier concentration at δ=0.3–0.6. However, Al2O3 doping in homologous phase In2O3-ZnO films decreased carrier concentration independently of the levels of Al2O3 doping. Al2O3 doped in the homologous ZnkIn2Ok+3 crystalline films did not act as a donor impurity. The optical band-gap energy for...

To clarify the involvement of G protein in denatonium signal transduction, we carried out a whole-cell patch-clamp analysis with isolated taste cells in mice. Two different responses were observed by applying GDP-beta-S, a G-protein inhibitor. One response to denatonium was reduced by GDP-beta-S (G-protein-dependent), whereas the other was not affected (G-protein-independent). These different patterns were also observed by concurrently inhibiting the phospholipase C beta2 and phosphodiesterase pathways via G protein. These data suggest dual, G-protein-dependent and -independent mechanisms for denatonium. Moreover, the denatonium responses were not attenuated by singly inhibiting the phospholipase C beta2 or phosphodiesterase pathway, implying that both pathways were involved in G-protein-dependent transduction. In the G-protein-independent cells, the response was abolished by the depletion of calcium ions within the intracellular store. These results suggest that Ca2+ release from the intracellular store is an important factor. Our data demonstrate multiple transduction pathways for denatonium in mammalian taste cells.

The films of ZnO–SnO2 system were deposited on glass substrates by simultaneous dc magnetron sputtering apparatus, in which ZnO and SnO2:Sb (Sb2O5 3 wt % doped) targets faced each other. The substrate temperatures were maintained at 150, 250, and 350 °C, respectively. As an experimental parameter, current ratio δ=IZn/(IZn+ISn), which corresponds to ZnO target current (IZn) divided by the sum of ZnO and SnO2:Sb target currents (IZn+ISn), was adopted. Amorphous transparent films appeared for 0.50⩽δ⩽0.73, which could be correlated to compositions as [Zn]/([Sn]+[Zn])=0.33–0.67 by x-ray fluorescent analysis. At [Zn]/([Sn]+[Zn])=1/2 (δ=0.62), 2/3 (δ=0.73) and all other ratios in as-deposited films, neither crystalline ZnSnO3 nor Zn2SnO4 was obtained. Minimum resistivity of 4–6×10−2 Ω cm was found at δ=0.50, whose composition was approximately SnO2⋅ZnSnO3. Resistivity increased linearly with an increase of the current ratio, until the composition reached Zn2SnO4. The amorphous phase showed a constant Hall mobility of ∼10 cm2/V s and a linear decrease in carrier concentration with increasing Zn content.

Thin ZnO–SnO 2 films were deposited on glass substrates by opposed planar magnetron sputtering, in which ZnO and SnO 2 :Sb (Sb 2 O 5 3 wt% doped) targets face each other. Glass substrate temperatures ( T s ) were held at 150°C and 250°C. As an experimental parameter, current ratio δ , ZnO target current divided by the sum of ZnO and SnO 2 target currents, was used. Compositions of as-deposited film were changed with the current ratio δ . Amorphous transparent films appeared over the range of 0.47⩽ δ ⩽0.80 (Zn/(Zn+Sn)=0.28–0.76) at T s =150°C, over the range of 0.33⩽ δ ⩽0.73 (Zn/(Zn+Sn)=0.32–0.66) at T s =250°C. Crystalline ZnSnO 3 and crystalline Zn 2 SnO 4 was not obtained in any of the as-deposited films, even at δ =0.62 (Zn/(Zn+Sn)=1/2) or δ =0.73 (Zn/(Zn+Sn)=2/3). Amorphous films exist as form of (ZnSnO 3 ) 1− x (SnO 2 ) x over the range of 0.50⩽ δ ⩽0.62 (0⩽ x ⩽0.5) and (ZnSnO 3 ) 1− y (ZnO) y over the range of 0.62⩽ δ ⩽0.73 (0⩽ y ⩽0.5). The minimum resistivity of the deposited amorphous films was 3.6 ×10 −2 Ω cm at δ =0.50 (Zn/(Zn+Sn) =0.33), T s =250°C.

The effects of Al 2 O 3 dopings in pseudobinary (In 2 O 3 ) 1− δ (2ZnO) δ films were investigated, and carrier generation mechanism was discussed. Here the δ value is the ratio of Zn/(Zn+In). For Al 2 O 3 doping below 2 wt%, low-resitivity amorphous films in 2–4×10 −4 Ω cm were deposited over a narrow range of δ =Zn/(Zn+In) (0.2⩽ δ ⩽0.4). At Al 2 O 3 =2 wt% doping, the resistivity was improved in the same narrow range of δ . Using a ZnO:Al target with 3 wt% Al 2 O 3, film resistivities of 2–4×10 −4 Ω cm were attained over a relatively wide range of δ in the amorphous phase (0.2⩽ δ⩽ 0.6). This result was due to the increase in carrier concentration at δ =0.3–0.6. The Al 2 O 3 doping also influenced on optical band gap: band gap shrinkage for Al 2 O 3 =2 wt% and band gap widening for Al 2 O 3 =3 wt%. For homologous crystalline films, Al 2 O 3 doping decreased carrier concentration, independent of the level of Al 2 O 3 doping. The Al 2 O 3 doping increased linearly optical band gap energy. These results indicate that the Al atoms are impurities that distort the lattice in homologous film.

Ion-exchange HPLC systems using POROS 20 HQ and Mono Q HR 10/10 columns were applied to isolate glycinin subunits under denaturing conditions. Analyses by SDS-PAGE, N-terminal amino acid sequence, and sucrose density gradient centrifugation showed that the pseudoglycinin from the highly purified homo-subunit, A3B4, was reconstituted. The A3B4 pseudoglycinin was similar to the native glycinin with respect to molecular size, subunit structure, and secondary structure. The hexameric pseudoglycinin dissociated into trimers after long storage at pH 7.6.

Structural and transparent conducting properties of amorphous Zn-In-O films deposited by simultaneous sputtering of ZnO and In 2 O 3 targets facing each other were reviewed. Post-annealing under the reductive gas flow was effective on improving unevenness of the amorphous films.

Two types of transglutaminases (TGases), Ca(2+)-dependent TGase derived from guinea pig liver (GTGase) and Ca(2+)-independent TGase derived from a variant of Streptoverticillium mobaraense (MTGase), were used to study the cross-linking of soybean 11S globulin (glycinin). The effects of sulfhydryl reductant (dithiothreitol, DTT) and Ca(2+) on the conformation and TGase-catalyzed polymerization of glycinin were investigated. The conformational change of glycinin was probed by spectral methods. The degree of cross-linking and the polymer (aggregate) formation were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and dynamic light scattering, respectively. Addition of DTT stimulated the TGase-catalyzed cross-linking reactions without destroying the secondary and tertiary structure of glycinin but did not influence the polymer or aggregate formation. It was found that Ca(2+) caused the formation of larger size polymers at lower concentrations, while it suppressed the polymerization at higher concentrations. In addition, the cross-linking behaviors of glycinin were shown to be different between MTGase- and GTGase-catalyzed systems.

A 4 polypeptide-containing (Shirotsurunoko and York) and A 4 polypeptide-lacking (Raiden and Suzuyutaka) soybean cultivars were used to investigate the heterogeneity of glycinin molecular species. Purification of glycinin by DEAE-Toyopearl column chromatography afforded molecular species eluting before the glycinin fraction. Analysis of this fraction by SDS–polyacrylamide gel electrophoresis (SDS–PAGE) and sucrose density gradient centrifugation indicated that this protein consisted of A 1 and A 2 polypeptides. The A 4 -containing soybean cultivars contained less of this protein than the A 4 -lacking soybean cultivars, as exhibited by the size of the early peak appearing during column chromatography. Alkaline PAGE and N-terminal amino acid sequence analysis confirmed that the A 1 - and A 2 -rich molecular species in the A 4 polypeptide-lacking cultivars consisted of the A 1a and A 2 polypeptides. Estimation of the molecular mass by gel permeation chromatography and multi-angle laser light scattering (GPC–MALLS) indicated that the A 1a - and A 2 -rich molecular species were similar to a monomer of glycinin.

Heat-induced gels were prepared from glycinins of various soybean cultivars at protein concentrations of 18 to 20%. Textural properties of the gels measured by a compression-decompression test were evaluated by the three-dimensional representation of the gels through factor analysis of the instrumental data and calculation of factor scores for each gel. Differences in gel texture were clearly observed among the soybean cultivars,with Shirotsurunoko gel being the most fracturable and Yamabe-A3 gel the most unfracturable. The most elastic was the gel from Hill and Matsuura gel exhibited the lowest elasticity. The existence of A4 polypeptide also contributed to the textural features of the gels. The gels of A4-containing cultivars were more unfracturable and less elastic compared to those of A4-lacking cultivars. Physical properties of the gels, gel network structure, and polypeptide composition of the glycinin were related each other to some extent. The compressibility which corresponded to the textural attribute of fracturability was related to regularity and/or pore size of network structure of the gels. The acidic polypeptide of A4 seemed to be responsible for whether the gel network was aggregate or strand type, thereby relating to the physical properties of compressibility and resiliency of the gels. The results obtained here suggest that polypeptide composition of the glycinin affects the properties of gel networks and thereby contributes to different physical and textural properties of the gels.

l-Theanine is a unique amino acid present in green tea. It elicits umami taste and has a considerable effect on tea taste and quality. We investigated l-theanine activity on the T1R1 + T1R3 umami taste receptor. l-Theanine activated T1R1 + T1R3-expressing cells and showed a synergistic response with inosine 5′-monophosphate. The site-directed mutagenesis analysis revealed that l-theanine binds to l-amino acid binding site in the Venus flytrap domain of T1R1. This study shows that l-theanine elicits an umami taste via T1R1 + T1R3.

Monosodium glutamate (MSG) elicits a unique taste in humans called 'umami' that is potentiated synergistically by the 5′-ribonucleotides IMP and GMP.Recent studies suggest that several mechanisms are involved in the transduction of umami taste. We have previously shown that MSG (10 mM) induced three different responses in mouse taste cells under whole-cell voltage-clamp in Na+ free Ringer solution; transient inward current, sustained inward current and outward current. Two, and occasionally all three types of currents, were observed in the same cell. We report here responses of mouse taste cells to the metabotropic glutamate receptor agonist, L-AP4 (1 mM), a mixture of MSG (10 mM) and IMP (0.5 mM), and a mixture of L-AP4 (1 mM) and IMP (0.5 mM) under whole-cell voltage-clamp. The mixture of MSG and IMP induced three different types of responses, similar to MSG alone. But the amplitudes of both the transient and sustained inward currents were larger than observed with MSG alone. The outward currents were similar in amplitude to those elicited by MSG alone. L-AP4 induced only outward currents in taste cells, while the mixture of L-AP4 and IMP induced both sustained inward currents and outward currents. These results suggest that umami taste reception may involve the coactivation of mGluR4 and one or more types of ionotropic glutamate receptors. Presumably the net transduction current resulting from activation of these receptors mediates the umami taste response, while an additional receptor or receptor site which is related to sustained inward current response, is involved in the synergistic effect of ribonucleotides.

We have previously reported that monosodium glutamate (MSG) stimulation elicited three types responses (transient inward current, sustained inward current and outward current) while L-AP4 (a potent mGluR4 agonist) evoked only outward currents in C57BL/6J mouse taste cells. The outward current responses to MSG and L-AP4 appeared to be mediated by metabotropic glutamate type 4 receptors (mGluR4). In this study, we examined whether agonists of ionotropic glutamate receptor agonists (NMDA, AMPA and ibotenic acid) also elicit responses in mouse taste cells. NMDA (1 mM) elicited transient inward currents, similar to those often observed with MSG, indicating the presence of NMDA receptor/channels that are permeable to Ca2+ ions and are activated by MSG in some taste cells. The sustained inward current response to MSG appeared to result from activation of a nonselective cation conductance, but it is not known if this response is coupled to ionotropic or metabotropic receptors. AMPA (1 mM) elicited small outward currents in all responding cells. Ibotenic acid, which produces a considerably stronger umami taste than MSG in humans, elicited two types of responses in isolated cells; transient inward currents and sustained inward current, suggesting that inward, as well as outward, currents are related to umami transduction. Also, we confirmed that MSG, AP4 (2 mM) and NMDA all can increase [Ca2+]i in taste cells. These results indicate that some cells have both metabotropic and ionotropic receptors, while other taste cells have only one or the other type of receptor.

Monosodium glutamate and nucleotides are umami taste substances in animals and have a synergistic effect on each other. We studied the ligand-binding properties of the glutamate receptors in taste epithelial cells isolated from bovine tongue. Specific glutamate binding was observed in an enriched suspension of taste receptor cells in Hanks' balanced salt solution, while no specific glutamate binding was apparent in the absence of divalent ions or when the cells had been depolarized by a high content of potassium in Hanks' balanced salt solution. There was no significant difference between the release of glutamate under depolarized or divalent ion-free conditions and under normal conditions. However, glutamate was easily released from the depolarized cells in the absence of divalent ions. These data suggest that the binding of glutamate to receptors depends on divalent ions, which also have an effect on maintaining binding between glutamate and receptors.

The copolymerization of p-tert-butoxystyrene (TBOSt) (M1) and di-n-butyl maleate (DBM) (M2) with dimethyl 2,2′-azobisisobutyrate (MAIB) in benzene at 60°C was studied kinetically and by means of ESR spectroscopy. The monomer reactivity ratios were determined to be r1 = 2.3 and r2 = 0 by a curve-fitting method. The copolymerization system was found to involve ESR-observable propagating polymer radicals under practical copolymerization conditions. The apparent rate constants of propagation (kp) and termination (kt) at different feed compositions were determined by ESR. From the relationship of kp and f1 (f1 = [M1]/([M1] + [M2])) based on a penultimate model, the rate constants of five propagations of copolymerization were evaluated as follows; k111 = 140 L/mol s, k211 = 3.5 L/mol s, k112 = 61 L/mol s, k212 = 1.5 L/mol s, and k121 = 69 L/mol s. Thus, a pronounced penultimate effect was predicted in the copolymerization. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1449–1455, 1998

Physicochemical properties of soybean oil extracted from γ-irradiated soybeans (0–10kGy) were investigated. No significant changes were observed in the total lipid content, fatty acid composition, acid value, peroxide value and trans fatty acid content at different irradiation doses. A tendency toward increase induction period was observed as irradiation dose increased. At higher dose levels than 10 kGy, n-hexanal content remarkably increased as dose levels increased, showing the possibility of a chemical index for over-dose irradiation in soybeans.

Gluconate is used as an additive in a wide range of processed foods. In this study, we investigated its utility as a taste-improving substance. To determine whether it has a suppressive effect on bitter taste, sensory evaluations were performed by human subjects. When gluconate was added to a quinine-HCl (QHCl) solution, the taste intensity decreased, but this effect was not observed when it was added to caffeine and to naringin solutions. Then we investigated the mechanism of suppression by performing behavioral and electrophysiological assays on mice. In mice, the addition of gluconate improved the taste preference for and reduced the gustatory nerve response to QHCl. In sum, gluconate had a suppressive effect on the bitter taste of QHCl, which might have been caused by depression of gustatory nerve activity.

乳清タンパク質ゲル物性へのキチン粉末添加の影響を検討し,次のような結果を得た.(1) タンパク質濃度を増すことにより,乳清タンパク質ゲルの「かたさ」,「弾性体近似値」,「弾力性」に関する力学的特性値は増加したが,「脆さ」に関する特性値は変化しなかった.(2) キチン粉末を添加することにより,乳清タンパク質ゲルの「かたさ」に関する力学的特性値が減少した.これはタンパク質濃度を増加させた場合の変化とは異なるものである.しかし,キチン添加により,「弾性体近似性」に関する力学的特性値は増加し,「脆さ」の特性値は変化しなかった.これらはタンパク質濃度を増した場合の結果と同様である.(3) ゲルの「弾力性」に関する特性値へのキチン添加の影響は,30分と60分加熱のゲルでは異なった.すなわち,前者では減少する傾向が,後者では増加がみられた.これらの結果から,キチン粉末を添加することにより,乳清タンパク質ゲルの「かたさ」が前報3)の卵白とは対照的な変化を示すことがわかった.キチン粉末添加のゲル物性への影響はタンパク質の種類をはじめゲル化条件によっても異なることが示唆された.

卵白ゲル物性へのキチン粉末添加の影響を検討し,次のような結果を得た.(1)卵白ゲルの物性はタンパク質濃度を増すと変化し,「かたさ」,「脆さ」に関する特性値は増加したが,「弾力性」,「弾性体近似性」に関する特性値は減少した.(2) 卵白にキチン粉末を添加することにより,上記のタンパク質濃度を増した場合と同様の物性変化をもたらすことが見いだされ,「かたさ」に関する特性値を増加させる効果があることがわかった.(3) 卵白にキチン粉末を添加した場合その粒径および添加量によってはタンパク質濃度を増した場合とは異なる物性変化をもたらす場合があることが見いだされ,「弾力性」,「弾性体近似性」に関する特性値を増加させるとともに,「脆さ」を増す効果があることがわかった.これらの結果から,キチンの粒径と添加量の組み合わせを工夫することによって,卵白ゲルの物性を改変あるいはコントロールする可能性が示唆された.

Fractionation of several kinds of membranes from the taste organ, circumvallate papillae, of bovine has been done to investigate localization of the umami substance binding site. Monosodium glutamate (MSG) and nucleotides are known as umami substances. The membrane fractions obtained from a series of centrifugation were examined for radioactive MSG binding activities by the ligand-binding methods, indicating a synergistic effect between MSG and nucleotides. They were also measured for activities of the marker enzymes. The membrane fraction that seemed to be rich in plasma membrane, on the basis of the marker enzyme activities, had specific MSG binding activity. These results suggest that umami substances bound to the plasma membrane of circumvallate papillae.

Flavanol-rich lychee fruit extract (FRLFE) is a processed lychee fruit extract that is higher in flavanols (monomers, dimers and trimers) than its unprocessed counterpart. FRLFE exerts antioxidant activities in vitro and is expected to protect against inflammation and tissue damage. However, the physiological effects of FRLFE intake have not been explored in vivo. The aim of this study was to examine the effects of FRLFE supplementation on inflammation and tissue damage in young athletes during intense physical training. Twenty healthy male long-distance runners at a university were randomly assigned to receive FRLFE or placebo in a double-blind manner. Blood and serum parameters associated with inflammation, tissue damage and oxidative stress were evaluated before (pre-training), during (mid-training) and after (post-training) a 2-month training period. Some parameters, including the white blood cell count, were significantly modified by FRLFE supplementation. Compared with the placebo group, the change in the serum interleukin-6 level between pre- and mid-training were significantly lower in the FRLFE group, while the change in the transforming growth factor-β level between pre- and post-training was significantly greater in the FRLFE group. These findings suggest that FRLFE supplementation may suppress inflammation or tissue damage caused by high-intensity exercise training.