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The ginger rhizome has been known to contain proteolytic enzymes. In this study, we evaluated the protease activities in juice extracted from ginger rhizomes. The specific protease activity in juice from ginger ripened after harvesting was higher than that of ginger that was not ripened after harvesting. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicated that the ginger rhizome juice displaying high specific protease activity contained a 30 kDa protein. This juice was also observed to have milk gel-forming ability.

Poly-γ-glutamic acid (PGA) was easily phosphorylated by direct addition of phosphorylating agents into the culture medium of Bacillus subtilis (natto). Tetrapolyphosphate salt was the most incorporated into PGA molecules of all used reagents. Phosphorylation occurred at the α-carboxyl side chains of PGA molecule. The amounts of bound phosphate to PGA were dependent on the amounts of added phosphorylating agent. In low molecular weight regions of less than 100 kDa, a cross-linked peak was observed in the phosphorylated PGAs, whereas their peaks at approximately 1000 kDa shifted to a higher molecular weight due to the bound phosphate. The PGA derivatives had a wide range in viscosity up to 15/1000 to 15 times when compared to the native PGA, depending on the degree of phosphorylation (DP) in the PGA derivatives. The PGA with low DP had a high viscosity due to the unfolding conformation whereas highly phosphorylated PGA had aggregation with low viscosity. Heat treatment at 80 °C after the addition of phosphate salt elicited a novel collagen-like helix structure. These observations show that phosphorylation is an effective way to diversify the physicochemical properties of PGA.

The effect of thermally processed rice koji extracts on survival of yeast Saccharomyces cerevisiae was examined in comparison with non-heated koji extract. In chronological life span (CLS) tests on high-sugar fermentation, the survivals of the yeast cells grown with heated koji extracts were higher than non-heated koji extract. Heat treatment of the extracts by autoclaving led to a loss in most of amino acids due to the Maillard reaction, although histidine contents slightly increased. In glucose-arginine mixtures, arginine was partly converted to histidine by autoclaving and the addition of histidine prolonged the CLS of yeast cells. The yeast cells grown with the non-heated extracts were more resistant to oxidative stress whereas the antioxidant activities were lower than those of the heated extracts. The yeast cells grown with the heated extracts were more tolerant to ethanol and had a higher reduction capacity in the late stationary phase when the cells were incubated in the presence of ethanol. Maillard reaction products elevated the levels of reactive oxygen species to yeast cells grown under ethanol stress in the late stationary phase. These results suggest that thermally processed koji extracts can act as a protectant against ethanol stress during the late stationary phase of yeast growth and extend the CLS due to the increase of histidine contents by autoclaving.

Poly-γ-glutamic acid (PGA) was modified with phosphorylating agents such as sodium metaphosphate and potassium metaphosphate in the culture medium of Bacillus subtilis (natto). The highly phosphorylated PGA derivatives were prepared and investigated for their chemical and physicochemical properties. The PGA derivatives had approximately 7% (W/W) inorganic phosphorus and characteristic absorbance PO2− bands at 1082 cm−1 and 1260 cm−1 by Fourier Transform Infrared Spectroscopy. The derivative modified by sodium metaphosphate (J-5) was easily hydrated in water and had extremely low viscosity. The shear rate-induced transition leading to the decrease of viscosity was not observed in J-5 whereas the derivative modified by potassium metaphosphate (J-6) as well as unmodified PGA (J-1) showed the typical decrease of viscosity. In circular dichroism (CD) measurement of J-5, there was a significant loss of the negative chirality CD signal, implying that protein aggregation occured at decreasing pH from 6.2 to 4.4. The thioflavin T fluorescence intensity of the aqueous solution in the J-5 was extremely high despite the absence of heat-treatment. The results indicate that the J-5 is the likeliest type of aggregation by β-sheet cross-linking which is relevant to protein diseases like Alzheimer’s disease.

Effect of the polysaccharide from leaves of Corchorus olitorius L. (PLC) on the freeze-thaw (FT) stability of corn starch gel was studied. PLC was incorporated into the starch gel at 0.7% and total solid was adjusted to 6.0%. The syneresis was measured by the centrifugal-filtration method and, as a result, addition of PLC reduced effectively the syneresis of the starch gel even after 5 FT cycles, which was less than one third that of the normal starch gel. The rheological changes of the starch/PLC gel during the FT treatments were evaluated while the gel remained on the rheometer plate. The starch/PLC gel had less significant changes in the rheological parameters during the FT cycles than starch/guar gum or xanthan gum gel systems. SEM images showed that PLC stabilized the gel matrix surrounding pores, which would contribute to both a lower syneresis production and a higher stability in the rheological behavior at FT.

Citrus pectin was modified with glycine, glycine methyl ester, or glycylglycine by the use of intramolecular associations in polar organic solvents. The modified pectins except glycine methyl ester significantly improved its dissolution in water, compared with unmodified pectin. The pectin modified with glycylglycine was the most soluble into water and was not influenced by pH range from 4.6 to 7.6 and ionic strength range from 1 mM to 50 mM phosphate buffer (pH 5.1), while the dissolution of the unmodified pectin decreased as pH and ionic strength increased. The required time at 45 °C at 95% hydration rate in the glycylglycine-modified pectin (2%, w/v) was toward 58% that in the unmodified pectin. In glycylglycine-modified pectin, the hydration rate was dependent on the bound amounts of the modifying agent to pectin. The potentiometric titration curves revealed that the glycylglycine-modified pectin would bear more negative charge than the unmodified pectin. From analysis of the water adsorption isotherms, the Brunauer–Emmett–Teller C constant as an index of hydrophilicity in the glycylglycine-modified pectin was 1.23-fold and 1.87-fold, respectively, higher than those in the unmodified and glycine methyl ester-modified pectins. These results suggested that the dissolution of pectin into water was preferably related to the net charge and the surface hydrophilicity in pectin molecules.

In this paper, unconstrained gravity model for urban trip pattern is formulated according to the entropy maximizing framework. It is reduced by maximizing the occurence probability of trip pattern subject to the total trip cost, which is the mixture of Wilson's and Sasaki's entropy models. Some characteristics useful to understand the structure of the gravity model were found by a precise observation on an analytical aspect of the model. A new method for parameter estimation for the gravity model is also proposed in our study: parameters for the unconstrained gravity model are estimated only by solving a non-linear equation witch is reduced from constraints of the entropy maximizing problem, and the uniqueness of the estimator has been veriaed mathematically.

As a rule, data to be used in locational analysis are either rounded up or rounded down. Therefore, error is incurred if such location data are used. The objective of this paper is to examine location error and cost error due to rounding in unweighted minisum and minimax problems in one-dimensional continuous space. Several conclusions on rounding effects are obtained by examining the respective mean-squared errors. First, rounding tends to exert more serious influence on the minisum problem than on the minimax problem. Second, in both location problems, the location error shows a pattern that is the inverse of that of the cost error.

α-Mannosidase (EC 3.2.1.24) was purified from ‘Iseimo’, a native variety of Dioscorea opposita Thunb. Before purification, we investigated the composition of a viscous polysaccharide that interferes with column chromatography procedures. The polysaccharide consisted mainly of mannose, and also contained uronic acid. We used the cationic detergent cetylpyridinium chloride (CPC) to remove the polysaccharide. CPC treatment decreased viscosity without affecting α-mannosidase activity. We purified α-mannosidase 2,650-fold. The optimal pH of the enzyme was 6.0 and the optimum temperature was 65°C. The Km value for p-nitrophenyl-α-d-mannopyranoside was 0.35 ± 0.03 mM. Activity was inhibited by swainsonine but not kifunensine. The enzyme cleaved α-1,2 linkages preferentially to α-1,6 and α-1,3 linkages. The Mr of purified α-mannosidase was estimated to be 250–260 kDa by gel filtration and native-PAGE. Four polypeptides (86, 83, 80, and 28 kDa) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It is unclear whether the polypeptides are encoded by one gene or multiple genes. However, N-terminal sequence analysis suggested that post-translational cleavage and/or glycosylation resulted in the three large fragments, if these amino acids were encoded by the same gene. Homology searches and characterization of the enzyme’s properties indicated that Iseimo α-mannosidase belongs to the glycoside hydrolase family 38 proteins, and to the Class II mannosidase group.

Precipitation from alcohol used against fractionation of polysaccharides was applied as an energy-efficient chemical modification with only a co-precipitation of polysaccharide and the modifying agent in polar organic solvents, and drying. Addition of ethanol caused a conformational change of polysaccharides with increasing intramolecular hydrogen bonding and a dense structure in close proximity to atoms, especially, in the presence of modifying agents. Extent of modification depended on the structure of polysaccharides and pH in polar organic solvents. The co-precipitates in polar organic solvents seem to act as a precursor while still maintaining the integrity of the modified polysaccharides. Eventually, a small amount of polar organic solvents (1.5 times volume to the weight of the mixtures) to disperse the reaction mixtures was enough to complete modification.

Viscous hydrocolloid from leaves of Corchorus olitorius L. was fractionated with ammonium sulfate solution (50%, w/v) followed by the stepwise extraction with distilled water. The yield of the hydrocolloid was 4.5% (w/w) based on dry material. Ash, protein, moisture and total sugars were 3.4, 5.3, 12.3 and 83.8% based on dry-material, respectively. The hydrocolloid consisted of mainly uronic acid and the weight ratio was approximately 90% of total sugars. When the molecular weight distribution was checked by size-exclusion chromatography, the hydrocolloid showed a wide uronic acid peak with a molecular weight of 940 kDa. The viscoelastic properties of the hydrocolloid were examined by low-amplitude oscillatory measurements and the hydrocolloid exhibited gel-like character at the concentration higher than 0.5% (w/w). Viscosity of the hydrocolloid surpassed other food hydrocolloids such as guar gum and locust bean gum at the same condition (0.25∼1.0% [w/w], 25 °C). When the hydrocolloid was heated over 60 °C (∼100 °C), an irreversible increase in viscosity was observed, suggesting the conformational change of the polysaccharide molecule.

The solid angle, which is closely related to the sky amount and sky factor, has been commonly used to assess urban landscapes. In this paper, we propose a new algorithm to calculate the solid angles of urban landscapes based on computational geometry. This algorithm enables us to incorporate the complicated landscapes which consist of multiple nonconvex polygons. Furthermore, using the algorithms, we assess the public space near Shibuya Station in terms of solid angles. In the analysis, we describe how advertising billboards disturb our visibility. We also develop the algorithm to calculate the sky amount and the sky factor, and evaluate both indexes.

Pectins were extracted from the peel of Citrus unshiu Marcovitch × C. nobilis Loureiro (Kara mandarin) in the presence of citric acid at different pH and temperature. Treatment with citric acid, particularly, at neutral pH gave a significant increase in viscosity. The citric acid treatment at high temperature led to decreased viscosity although the viscosity remained higher than that of untreated pectin. Pectin methylesterase activity was inhibited at high citric acid concentrations. The increase in viscosity of treated pectin was proportional to the amounts of citric acid bound to pectin. The pectin with citric acid treatment had a low degree of methylation (8.4%) and a high distribution (50 to 2000 kDa) of molecular mass than untreated pectin. Analysis of chemical composition showed that the pectin with citric acid treatment contained lower protein and galacturonic acid, and higher neutral sugars, particularly, galactose than the untreated pectin. The citric acid treatment at neutral pH prior to extraction is an attractive procedure for low methoxy pectin without lowering its molecular weight.

BACKGROUND: The relationships between possible physiological properties of insoluble fibre and the viscosity of digesta are poorly understood. The aim of this study was to investigate the effect of insoluble fibres with different water-holding capacity, swelling, oil-holding capacity and cation exchange capacity on gastric, small intestinal and caecal contents in rats fed a semi-purified diet containing either no fibre (control), 50 g kg−1 tossa jute fibre or 50 g kg−1 shiitake fibre. RESULTS: The water-holding capacity, swelling, oil-holding capacity and cation exchange capacity of insoluble fibres of tossa jute were higher than those of shiitake (P < 0.001). The order of the viscosities of digesta was control group < shiitake fibre group < tossa jute fibre group in gastric, small intestinal and caecal contents (P < 0.05). The digesta viscosity at a shear rate of 40 s−1 was strongly correlated with the free water content of digesta (r = − 0.89; P < 0.01). The free water content of digesta depended on the water-holding capacity of insoluble fibres represented as a linear function with negative slope (P < 0.001). CONCLUSION: The viscosity of digesta depends on the free water content, and this is reduced by fibre that holds water and can swell. Copyright © 2008 Society of Chemical Industry

Hydrocolloid from leaves of Corchorus olitorius was fractionated with ammonium sulfate (50%, w/v) and extracted with distilled water. The yield of the hydrocolloid was 6.0% (w/w) based on dry material. The contents of total carbohydrate, anhydrouronic acid, ash, protein, and moisture of the hydrocolloids were 62.2%, 35.3%, 13.3%, 5.5%, and 16.1% (w/w), respectively. Degree of esterification of 19.4% was calculated assuming that the methoxyl groups were attached to only anhydrouronic acid. When the molecular weight distribution was checked by size-exclusion chromatography on Sepharose CL-4B, the hydrocolloid gave a single peak with a molecular weight of 1860 kDa. The rheological behavior of mixed gels made from κ -carrageenan and the hydrocolloid at a total hydrocolloids concentration of 1% (w/w) was investigated by gel strength measurement. Then it was found that the hydrocolloid exhibited synergy with κ -carrageenan in relation to gel strength.

In this paper, the optimal numbers of gas and hydrogen stations are examined. Recently, the possibility of gasoline vehicles being replaced with fuel cell vehicles (FCV) is being examined in the coming hydrogen society. The realization of this scenario however needs a large number of hydrogen refueling stations, which hardly exist at the present. We first calculate the optimal number of hydrogen stations to minimize the sum of two types of cost: 1) operation cost of hydrogen stations and 2) transportation cost of FCVs to the nearest stations. Next, we incorporate the diffusion rate of FCVs into the model to determine the optimal number of gas stations and that of hydrogen stations simultaneously. We also provide an advanced model that considers hybrid stations, with which both gasoline and FCVs can refuel. These models clarify that the optimal number of total stations varies with the diffusion rate of FCVs. If only gas and hydrogen stations are assumed, more stations are needed in the transition period. If hybrid stations are introduced, the number of total stations takes minimum value during the transition period. Moreover, the optimal solution indicates that all stations should become hybrid stations in the middle of the transition. Finally, the models are applied to Yokohama City in Japan and the solutions of the models are examined.

Pectic substances were extracted from Japanese pepper (Zanthoxylum piperitum DC) fruit with hot diluted HCl (90°C, pH 2.2). The yield of the pectic substances was 8.4% (w/w) based on dry material. The contents of total carbohydrate, anhydrogalacturonic acid, ash, protein, and moisture of the pectic substances were 84.1, 66.9, 3.6, 2.7, and 9.6% (w/w), respectively. The degree of methylation was estimated to be 80.3% by using alcohol oxidase test. This indicated that the pectic substances are high methoxyl pectins and have an ability to form sugar gels. The jelly grade of the pectic substances was estimated to be 130 (USA-SAG) at standard condition. Viscosity-average molecular weight was relatively low (30.3 kDa). When the molecular weight distribution was checked by gel-permeation chromatography on Sepharose CL-4B, the elution profile of the pectic substances was highly polydispersed extending from 40 kDa (or less) to 2000 kDa.

The dye-sensitized solar cells (DSCs) were assembled by using natural carotenoids, crocetin (8,8′-diapocarotenedioic acid) and crocin (crocetin-di-gentiobioside), as sensitizers and their photoelectrochemical properties were investigated taking a presence or absence of carboxylic group in the dye molecule into consideration. In these carotenoids, crocetin that has carboxylic groups in the molecule can attach effectively to the surface of TiO2 film so that it performed the best photosensitized effect resulting in the short-circuit photocurrent with 2.84 mA under irradiation of 1.0 cm2. On the other hand, crocin that has no carboxylic group in the molecule showed lower photoelectrochemical performance because of its lower affinity to the surface of TiO2 film. These results indicate that it is possible to apply carotenoid as sensitizers for DSCs at the presence of effective function groups.

Antioxidants were extracted from Japanese pepper ( Zanthoxylum piperitum DC.) fruit and characterized. The antioxidant activity of the methanol extract from Japanese pepper fruit was found to be equal to that of α-tocopherol and stable under heat treatment. The main compounds that gave a significant antioxidant activity from the methanol extract were identified to be hyperoside (quercetin-3- O -galactoside) and quercitrin (quercetin-3- O -rhamnoside) as determined by HPLC, mass spectrometry, UV/Vis spectroscopy, and TLC. Radical-scavenging activities of hyperoside and quercitrin from Japanese pepper fruit were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. As a result, hyperoside and quercitrin scavenged DPPH radical strongly with IC 50 values of 16 and 18 μM, respectively. These observations show the presence of strong antioxidants, namely hyperoside and quercitrin in Japanese pepper fruit.

Kinetics of fatty acid binding ability of glycated human serum albumin (HSA) were investigated by fluorescent displacement technique with 1-anilino-8-naphtharene sulphonic acid (ANS method), and photometric detection of nonesterified-fatty-acid (NEFA method). Changing of binding affinities of glycated HSA toward oleic acid, linoleic acid, lauric acid, and caproic acid, were not observed by the ANS method. However, decreases of bind-ing capacities after 55 days glycation were confirmed by the NEFA method in comparison to control HSA. The decrease in binding affinities was: oleic acid (84%), linoleic acid (84%), lauric acid (87%), and caproic acid (90%), respectively. The decreases were consistent with decrease of the intact lysine residues in glycated HSA. The present observation indicates that HSA promptly loses its binding ability to fatty acid as soon as the lysine residues at fatty acid binding sites are glycated.