6-O-Monolinoleoyl trehalose synthesized by the immobilized-lipase-catalyzed condensation of linoleic acid and trehalose was dissolved in water at various concentrations, and its oxidation processes were then measured at 35°C based on both the decrease in the linoleoyl residue and oxygen consumption. The stoichiometric coefficient of oxygen to the linoleoyl residue was in unity except during the late stage of the oxidation. The oxidation process could be expressed by the rate equation of the autocatalytic type. The rate constant was higher for the higher substrate concentration, but it was not in proportion to the concentration at substrate concentrations higher than its critical micelle concentration. These results suggested that the migration of oxygen into the hydrophobic core of the linoleoyl residues through the hydrophilic trehalose layer of the linoleoyl trehalose micelles affected the overall oxidation rate of the linoleoyl residue.
Dry heated wheat flours were fractionated into water-soluble, gluten, prime-starch and tailings fractions by an acetic acid fractionation technique. With a gradual increase in the duration time at each temperature, recovery of the prime-starch fraction decreased while the tailings fraction increased. However, the water-soluble and gluten fractions did not change, which is indicated by the fact that interaction between the prime-starch and the tailings fractions occurred for these treatments. A mixograph profile showed hydrophobicity of the wheat flour by dry heating. These dry heated wheat flours gave a large pancake springiness. The temperatures and the duration times for complete pancake springiness were as follows ; at 60°C for 540h (22.5 days) ; 70°C for 144h (6 days) ; 80°C for 72h (3 days) ; 90°C for 24h (1 day) ; 100°C for 6h ; 110°C for 4h ; 120°C for 2h. Interaction between the prime starch and the tailings fractions in wheat flour produced by dry heating was highly correlated to improvements in the pancake springiness.
As a part of our research project on the elucidation of the chain-breaking antioxidant mechanism of natural phenolic compounds in food components, ferulic acid, a phenolic acid widely distributed in edible plants, especially grains, was investigated. An antioxidation reaction of ferulic acid methyl ester produced a main product when ethyl linoleate was used as the oxidation substrate. Isolation and structure determination of the main product revealed that it was a dimer having a dihydrobenzofuran moiety. On the basis of the formation pathway for the product, a radical scavenging reaction was suggested to occur between the 5′-position of one of the ferulate radicals and the 2-position of another of the ferulate radicals to terminate the radical chain oxidation of linoleate.
Changes in the radical-scavenging activities and the total phenol content of sixteen spices (clove, allspice, cinnamon, nutmeg, mustard, cumin, ginger, fennel, fenugreek, black pepper, red pepper, mace, coriander, turmeric, cardamom and white pepper) were determined for different heating times (1, 3 and 6h) at 100°C. Most of the spices showed high 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity (4-1353μmol Trolox eq./g), peroxy radical-scavenging activity (31-1019μmol Trolox eq./g), and total phenol content (5-1267μmol gallic acid eq./g). Clove was found to have the highest radical-scavenging activity followed by allspice and cinnamon. After heating, both DPPH and peroxy radical-scavenging activities as well as the total phenol content increased in most of the spices. A distinct increase in the activities was found in some spices such as black pepper, red pepper and turmeric. A high correlation coefficient was found between the total phenol content and peroxy radical-scavenging activity.
Niihime fruit, produced in the coastal area of the Sea of Kumano in Mie prefecture, is a new sour citrus fruit. This is the first study to examine the characteristics of the flavonoids in niihime fruit. The content of flavonoids in the juice and peel of niihime fruit was determined by HPLC and their distribution was examined in comparison with seven other species of sour citrus fruits. Niihime fruit was found to contain a comparatively high quantity of bioactive flavonoids of the flavanone glycosides with rutinose sugar chain such as eriocitrin and hesperidin as well as the polymethoxyflavones such as nobiletin and tangeretin. The peel extract of niihime fruit exhibited comparatively high antioxidative activity among sour citrus fruits using the DPPH radical scavenging assay. Furthermore, the flavonoids eluted from niihime fruit by over time in hot and cold solutions of water, 5% ethanol, and 25% ethanol, which are commonly used in the field of food processing and cooking, were examined. The flavonoids eluted from niihime fruit in hot 25% ethanol solution was highest content in solutions, and the content of flavonoids eluted in 5min was an approximate half of content eluted in 60min. The flavanone glycosides, eriocitrin and hesperidin, were eluted in higher contents in hot solutions than in cold solutions. The polymethoxyflavones, nobiletin and tangeretin, were eluted to some extent in hot 5% ethanol but were found in low contents in cold solutions. The highest contents were eluted in hot 25% ethanol. The difference in the elution properties between flavanone glycosides and polymethoxyflavones is considered to be a result of their hydrophobic properties. The scavenging activity of DPPH radical for eluates was shown to increase over time, and the activity was suggested to be related to the elution content of eriocitrin, which is an antioxidant in niihime fruit. This study showed that niihime fruit contains a comparative abundance of bioactive flavonoids and these flavonoids are able to be eluted using hot solutions of water and ethanol.
Several wild yeast strains isolated from spontaneous must fermentation were tested for use in winemaking. The ability of Saccharomyces cerevisiae GR7 and GR3 to produce a regular fermentation process, complete fermentation, and produce ethanol and low volatile acidity at both 12°C and 20°C indicate that both strains are promising as starter cultures in winemaking. The effect of wild yeast strains on the relative composition of several volatile compounds in wines fermented at 12°C or 20°C was also studied. Pinot Grigio must fermentation was carried out using selected yeast strains. In addition, Debina and Roditis wines were made by spontaneous must fermentation. Experimental wines were analyzed for volatile compounds using solid phase microextraction and GC-MS analysis. In all wines fermented at 12°C, most acetate esters, ethyl esters, higher alcohols and fatty acids were lower than in those fermented at 20°C.
Contents of rutin, free amino acids and vitamin C were measured with the sprouts of common buckwheat (Fagopyrum esculentum Moench, FE) and tartary buckwheat (F. tataricum Gaertn., FT), cultivated in darkness and/or under natural light conditions. Flavonoids, including rutin and quercetin were isolated from the sprouts of FE and FT by using HPLC and quantified with their authentic standard compounds. In FE sprouts, rutin content placed under natural light conditions was higher than from plants grown in darkness. In contrast, in FT sprouts rutin content was significantly affected both by days after seeding (DAS) and by lighting. On average, rutin content (55mg/g dry weight) of FT sprouts was 2.2-fold higher than that of FE sprouts. In both species, free amino acids levels were increased with increased natural light periods, and vitamin C content of the sprouts cultivated in darkness in both species was significantly lower than that of light-grown sprouts. Based on these characteristics, we concluded that the green sprouts of FT are a superior source of rutin, free amino acids and vitamin C. They could therefore be used as ‘functional foods’ fresh vegetables and freeze-dried powder.
A new method for producing fermented fish sauce was developed to improve the taste of the fish sauce. The method involved the production of a fermented sauce, seasoning liquid from salmon that was enzymatically hydrolyzed with the wheat gluten koji, lactic acid bacteria and yeast. During fermentation, the total nitrogen, lactic acid, and ethanol contents in the fish sauce increased continuously and then plateaued 3 months after fermentation had begun. We investigated the chemical composition and the sensory properties of the fish sauce prepared by this 3-month fermentation, and we compared these characteristics with those of the fish sauce from salmon similarly hydrolyzed with soy sauce koji prepared from soybean and wheat. The fish sauce produced using wheat gluten was very light-colored and had a higher content of free amino acids, especially glutamic acid. The peptides consisted mainly of Glx, Asx and Pro, compared with Asx, Glx, and Gly in the liquid from soy sauce koji. Sensory evaluation revealed that the fish sauce derived from the wheat gluten koji had an intense umami taste and a fine flavor better than that of soy sauce koji.
This paper describes the features of new characteristic rice cultivars developed in the Hokuriku region, especially Hokuriku 166 (floury mutant rice) and Hokuriku 169 (sugary mutant rice), in comparison with Koshihikari. Using Hokuriku 166, it is easy to make fine rice flour because the starch granules for this cultivar are globular and small. Therefore, this cultivar is popular because it is easy to handle. Hokuriku 169 has a high proportion of bran and high γ-aminobutyric acid (GABA) content. The fineness of Hokuriku 166 rice flour and the component parts of Hokuriku 169 are promising as raw material for processing.
Cladosiphon okamuranus (Okinawamozuku) is a species of Mozuku known to contain the most fucoidan of any brown algae. Fucoidan is a sulfated hetero polysaccharide with various biological activities. We isolated and purified fucoidan from C. okamuranus. The yield of fucoidan was 1.0% (w/w) based on wet algae from C. okamuranus. The sulfate content and molecular weight of the fucoidan were 9.8% (w/w) and approximately 3,200,000, respectively. We examined the effects of fucoidan on human stomach cell lines. Fucoidan from C. okamuranus showed an inhibitory effect on anticancer agent 5-fluorouracil (5-FU) in Hs 677.st normal stomach cells with minimum inhibition of the original effect of 5-FU in cancer cells. Furthermore, fucoidan from C. okamuranus showed growth inhibition of stomach cancer cells but did not show any effects on normal cells. Thus, fucoidan from Mozuku, especially C. okamuranus, may be useful for cancer therapy.
The volatile fraction of ninety-eight different vinegars was analysed using a head-space analysis instrument assembled in our laboratory. This instrument is formed by an automatic sample introduction system, directly coupled to a mass detector without performing any chromatographic separation. The aim of this research was to classify the vinegar samples according to raw material (white or red wine, Sherry, malt, apple, alcohol) and production process (with or without ageing in wood barrels). The information contained in the measured signals was analysed by different chemometrical techniques. Linear Discriminant Analysis was used as classification method, after applying a feature selection technique. The 100% of samples were correctly classified and predicted, by cross-validation procedure, according to raw material and according to the ageing process in wood barrels.
The present study investigated the fermentation of Jerusalem artichoke with or without the addition of Leuconostoc mesenteroides, Lactobacillus casei, or Lactococcus lactis as a starter. Seasoning brine, containing 2.5% NaCl and about 1.0×107cfu/ml starter bacteria when added, was mixed with sliced Jerusalem artichoke and fermented at 20°C. Whether the starters had been added or not, lactic acid bacteria became predominant in the brine, and consequently acidity was increased. Fermentation was completed in 6-7 days. Bacterial flora in the brines of fermented products was investigated by amplified ribosomal DNA restriction analysis (ARDRA) and sequencing of the 16S rRNA gene. When L. mesenteroides or L. lactis was used as a starter, the added strain was predominant in the product, suggesting attainment of controlled fermentation. In the case of L. casei, the starter strain did not prevail, and the final microbial flora was different from that of natural fermentation. These results indicate that L. mesenteroides and L. lactis have the potential to control Jerusalem artichoke fermentation.
Soluble polyphenol oxidase of edible yam (Dioscorea opposita Thunb.) was purified approximately 203-fold with a recovery rate of 15% by ammonium sulfate fractionation, ion exchange chromatography, hydrophobic chromatography and gel filtration using dopamine as a substrate. The purified enzyme appeared as a single band on native PAGE and SDS-PAGE. The molecular weight of the enzyme was estimated to be approximately 42kDa and 44kDa using gel filtration and SDS-PAGE, respectively. The purified enzyme quickly oxidized dopamine. The apparent Kmvalue (Michaelis constant) of the enzyme was 1.5mM for dopamine (pH 7.0, 30°C). The optimum pH was 7.0 for dopamine oxidase. In the pH range from 6 to 10, the activity was quite stable at 5°C for 22h. The optimum temperature of enzyme activity was 25-30°C. The activity was stable up to 50°C after heat treatment for 20min. The browning reaction by the enzyme was completely inhibited by 1mM L-ascorbic acid, which reduced o-quinone to dopamine. The reaction was also completely inhibited by 1mM L-cysteine, which is a known quinone coupler. About 35% inhibition of edible yam PPO was observed using citric acid and acetic acid at 10mM in 0.1M citrate/ 0.2M sodium phosphate buffer (pH 7). In consideration of the observed results, L-ascorbic acid, L-cysteine, acetic acid, and citric acid are expected to be used as effective inhibitors of enzymatic browning in edible yam.