The heat transfer characteristics of superheated steam (SHS) combined with far infrared heating (FIH) by a ceramic heater were compared with those of SHS and FIH performed separately. The heat transfer rate was evaluated from the drying rate of the water for each heating mode under the prescribed conditions. The heat transfer rate in SHS alone could be estimated well from semi-theoretical equations, which use an established empirical equation for the convective heat transfer coefficient. But the estimated values of the heat transfer rate in FIH were slightly smaller than the observed values. This indicates that the natural convective heat transfer rate should be slightly larger than that calculated using the empirical equation. FIH greatly enhanced the heat transfer rate of SHS. Further, some SHS stagnated in the vicinity of the ceramic heater and consequently was heated to a higher temperature, enabling additional radiative heat transfer. The effect of FIH on the heat transfer rate increased as the temperature difference between the ceramic heater and the SHS increased.
Linoleic acid was microencapsulated with gum arabic using a spray-drier with a centrifugal atomizer. The oxidation process of encapsulated linoleic acid was observed at various temperatures and at different relative humidities. The inlet-air temperature of the dryer was found to have no significant effect on the Sauter mean diameter or moisture content of the microcapsules ; hence, the oxidation process of encap- sulated linoleic acid was unaffected by the inlet-air temperature. However, the rotational speed of the atomizer did affect the size and moisture content of the microcapsules, which were found to be larger and higher, respectively, for microcapsules prepared at the lower rotational speed. The oxidation of linoleic acid in larger microcapsules proceeded more slowly. In addition, oxidation progressed more quickly at a higher relative humidity, and it was suggested that the glass transition of the wall material might affect the progress of oxidation. The oxidation process was analyzed based on the Weibull equation, and the rate and shape constants were evaluated. Relative humidity was found to have little effect on the activation energy of oxidation during storage of the microcapsules.
On the basis of growth rate at low pH, yield of lactic acid from glucose, and optical purity of lactic acid produced, we selected lactic acid bacteria favorable for production of optically pure L-lactic acid from defatted rice bran without sterilization. Of 21 strains tested, strains Nos. 13 and 16 produced 27-29kgm-3 of lactic acid with high optical purity from 100kgm-3 of unsterilized defatted rice bran in simultaneous saccharification and fermentation (SSF) with MRS medium at pH 4.5, a level at which the growth of indigenous lactic acid bacteria in defatted rice bran was suppressed. In a SSF process using strain No. 16 in which McIlvaine buffer (pH 4.5) was used instead of MRS medium, no growth of indigenous lactic acid bacteria was observed in defatted rice bran, and 28kgm-3 of lactic acid with 92% L-type content was produced from 100kgm-3 of unsterilized defatted rice bran. In SSF using McIlvaine buffer (pH 4.5), the protein fraction of defatted rice bran was found to play a significant role as a nitrogen source for the growth of lactic acid bacteria. By increasing the initial cell concentration to OD660=1.0 for SSF using strain No. 16 and McIlvaine buffer (pH 4.5), the proportion of L-lactic acid produced was enhanced to 95%.
The recrystallization of ice crystals in sucrose solution was investigated by cryo-SEM in a temperature range of -21°C to -50°C, including temperatures around Tg′. By using the technique of image analysis, the mean radius of the ice crystals was evaluated and recrystallization rates were calculated by a kinetic equation based on the Ostwald ripening principle. As the storage temperature decreased, a rapid decline in recrystallization rate was observed between -29°C and -35°C, which was consistent with the concept of glass transition of the freeze-concentrated matrix. Even at -50°C, at which the freeze-concentrated matrix was considered to be in glassy state, an increase in the mean crystal size was observed after 20hr storage.
We demonstrated that a dietary supplement, Antioxidant Biofactor (AOB®), a fermented grain food, inhibits phorbol ester (TPA)-induced inflammatory responses. Pretreatment of mouse skin with ethyl acetate extract of AOB (0.5mg) significantly attenuated the hydrogen peroxide level in mouse skin without inhibition of edema formation. Also, exposure of AOB extract to differentiated HL-60 cells resulted in dose-dependent inhibition of TPA-induced superoxide generation, which was stronger than those of the raw materials of AOB. Our results suggest that AOB is effective for prevention of skin oxidative stress.
The effects of konjac glucomannan on isoflavonoid levels in the plasma and cecum were assessed in adult mice. Male 5-week-old mice were fed on a konjac glucomannan-isoflavone (KM) diet or a cellulose-isoflavone (control) diet for three weeks. After this period, plasma equol levels were significantly higher in the KM group, but there was no significant difference in the plasma daidzein concentration. The ratio of plasma equol to plasma daidzein in the KM group was significantly higher than in the control group. The total amount of equol present as aglycone in the cecum was significantly greater in the KM group, but there was no significant difference in the total daidzein present as cecal aglycone. The total amount of glycitein present as aglycone in the cecum was significantly greater in the KM group. We have demonstrated that the ingestion of konjac glucomannan may enhance equol production by affecting the metabolic activity of intestinal microflora.
Chemical properties and textures of cooked rice prepared with aged rice grains were investigated and compared with those of cooked rice prepared with new rice grains. Differences in stickiness/hardness (S/H) ratios between new rice and aged rice were eliminated by the removal of the external layer of rice grains. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the proteins of the external layer in aged rice grains were oxidized to a greater extent than those of new rice grains. Addition of a reducing agent to cooking water increased the S/H ratio of aged rice to approximately that of new rice. The reducing agent cleaves the disulfide linkages of the proteins. Therefore, textural changes in aged rice were inferred to be due to oxidation of proteins in the external layers of grains.
We investigated the 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical-scavenging activity and antimutagenicity of alcoholic fermented beverages produced from cooked or raw purple-fleshed sweet potato (Ipomoea batatas cv. Ayamurasaki) roots. The beverage produced from cooked roots had higher DPPH-radical-scavenging activity and antimutagenicity than that produced from raw roots. To compare the anthocyanin quality contained in the beverages prepared with and without cooking, the kinds and relative amounts of pigments in the two beverages were compared. In both samples, we identified 10 peaks. The aglycones of the anthocyanins in both samples were cyanidin and peonidin. The beverage prepared with cooking contained particularly large amounts of acylated anthocyanins, and the beverage prepared without cooking contained large amounts of deacylated anthocyanins.
The relationship between ingestion of coffee and reduction of mental stress was investigated in 256 young Japanese women. Among the 68% of subjects whose questionnaire responses indicated that they liked coffee, 68% indicated they feel relaxed when they drink coffee. In an organoleptic test, coffee extracted at 80°C exhibited a greater relaxation effect than coffee extracted at 65 or 95°C. This effect showed a significant negative relationship to sourness, suggesting that the relative lack of sourness enhances feelings of relaxation. Coffee drinking also decreased experimentally-induced mental stress evaluated by chromogranin A concentrations.
We investigated the effects of white-skinned sweet potato (WSSP) on the expression of adipose tissue adipocytokine in order to elucidate the mechanisms underlying the anti-diabetic effects of WSSP. A significant blood glucose lowering effect was observed starting 1 week after repeated administration of WSSP to KK-Ay mice. Expression of ACRP30, which is a homolog of adiponectin, was significantly higher in the WSSP-treated group than in the control group. Tumor necrosis factor-α expression indicated low tendency (p=0.09) in the WSSP treated group. The WSSP-treated group showed a greater tendency (p=0.09) than the control group for expression of the β-3-adrenoreceptor. These results suggest that one of the mechanisms of anti-diabetic action of WSSP is associated with improved action to the abnormal secretion of adipose tissue adipocytokines.
Myrosinase (β-thioglucoside glucohydrolase, EC 188.8.131.52) is involved in pungency generation in wasabi (Wasabia japonica Matsum.). We isolated full-length cDNA (WjMY1) encoding myrosinase from the petiole of wasabi. The deduced polypeptide has 545 amino acids with a molecular weight of 62107. WjMY1 mRNA is accumulated in whole organs of the wasabi plant ; the order of expression is petiole≥rhizome>leaf. The order was found to be similar to that of the specific activity of myrosinase. This is the first report de- scribing the isolation of a myrosinase gene from wasabi.