Changes in antioxidant activity in the hypocotyles of mung bean sprouts as influenced by the quantity and quality of cell wall polysaccharides were evaluated. Although antioxidant activity gradually decreased as the hypocotyls matured, the highest activity was observed in hot water-soluble pectic fractions among four different cell wall fractions throughout the growing period. Degree of esterified galacturonan was negatively correlated with antioxidant activity, suggesting that the antioxidant activity of cell wall polysaccharides in mung bean sprout hypocotyles resulted from decreased esterification in the main chains of pectin molecules.

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The effects of moisture and temperature on the textural properties of a commercially produced cookie and senbei were examined by measuring breaking properties under storage conditions of relative humidity (RH) 7.6-97% at four temperatures, 5, 20, 40 and 60°C. A cookie with low gelatinization characteristics was softened with small amounts of moisture. Although the degree of softening was small at 5°C, it increased significantly with an increase in temperature. The cookie had a low moisture content and was softened with ductile fraction at 60 °C. The senbei, with high gelatinization characteristics, became hard, containing 11-18g moisture/100g dry matter. The maximum hardening value of senbei was reached at less than 11g moisture/100g dry matter at 40°C. This was thought to be due to the fact that the glutinous strength of gelatinized starch has a maximum value at around 40°C. The amount of moisture sorption per 100g dry matter of the cookie required to maintain hardness was approximately 8g at 5°C, 6g at 20°C, 4g at 40°C and 3g at 60°C. The amount of moisture sorption per 100g dry matter of the senbei required to keep hardness was approximately 20g at 5°C and 20°C, and 16-17g at 40°C and 60°C. The maximum amount of moisture sorption required for senbei to soften was large compared to that of the cookie. Based on textural evaluations, brittleness was lost and crunchiness maintained in cookies kept under RH 56% (7g moisture/100g dry matter). While the senbei under RH 68% (13g moisture /100g dry matter) was perceived to be moist and sticky, it was not easy to bite off.

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In the present study, gelatin was extracted from sardine scales using a novel pressurized hot water extraction method, and the extraction behavior and properties of of the extracted gelatin were investigated. The present method enabled stable extraction using only water, and no clogging of extraction tube filters was observed. The hydrolysis reaction became more pronounced at an extraction tube outlet temperature of 143-153°C, and virtually all sardine scale collagen was eluted within 8min at an extraction tube inlet temperature of 225°C (tube outlet temperature, 156-203°C). Extracted proteins consisted mostly of gelatin, but also a small percentage of ash thought to be apatite. In addition, no significant amino acid thermal decomposition was observed. Molecular weights of extracted gelatin ranged from approximately 443 to 6.5kDa at the peaks of the GPC curve, and decreased as extraction temperature increased. Gelatins in the peptide region that had narrow molecular weight distributions were obtained in the 400-1000mL fraction at an inlet temperature of 225°C.

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The application of aroma extract dilution analysis (AEDA) using volatile fractions before and after heat processing of citrus juice samples (grapefruit and orange) resulted in detection of 41 odor-active peaks, and 33 potent odorants, which are responsible for the characteristic flavor of each juice, were identified. Among these components, cis-4,5-epoxy-(E)-2-decenal was identified for the first time in citrus fruit. Based on a comparison of flavor dilution (FD) factors in these juice aromas, we found that both the odorants and flavors of juices are changed by heating. We were able to explain the flavor change in both types of citrus juice as the result of increases in six odorants during heat processing. Of these, 2-methyl-3-furanthiol was the odorant most responsible for the flavor change caused by heating.

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An inhibitory effect on the black discoloration of perishable food by a culture supernatant of fungi isolated from marine sediment gathered off the Niigima Islands was studied at the enzyme and application levels. The fungus was identified as Trichoderma sp. from a taxonomic study. The strain was incubated in 100ml of broth composed of 2% glucose and 0.5% Bacto-peptone, pH 8.0, in a baffled 500ml Erlenmeyer flask at 27°C for 4 days on a rotary shaker (160rpm). After incubation, the culture was harvested by centrifugation and a supernatant was used for the present study. The inhibitor was stable for more than 50 days under conditions of -20°C and -80°C without reduction of the inhibitory activity. When the supernatant was boiled for 30min, the inhibitory activity was reduced by about 50%. However, more than 90% of the activity remained after proteolytic enzyme digestion with papain, suggesting that the inhibitor might be applicable in preventing the black discoloration of perishable food. A remarkable preventative effect on the black discoloration of cultured prawns was observed in the presence of 0.2% culture supernatant. In addition, the supernatant diluted with 50% water also showed a 70% reduction in the black discoloration of fresh apple, eggplant, and mushroom. These results suggested that the inhibitor might be applicable to the preservation of perishable foods.

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Crustaceans are one of the most significant sources of food allergies, and tropomyosin is their major allergen. To detect crustacean allergens in food products, we have developed a sandwich ELISA using a crustacean tropomyosin-specific monoclonal antibody using black tiger prawn tropomyosin as an immunogen. Our ELISA showed 82-102% reactivity (based on reactivity to black tiger prawn tropomyosin) to tropomyosins from crustaceans including prawns, lobster, crab, hermit crab, and krill, while no substantial reactivity (<0.1%) to those from mollusks, including squid, octopus, and shellfish, was observed. Furthermore, no positive ELISA results were obtained with any crustacean-free foods. Repeatability coefficients of variation (CVs) were <10%, and the detection limit based on a standard crustacean protein was 0.16ppm, which qualified for the sensitivity requirements of the current food labeling system. The ELISA could detect crustacean tropomyosin, even heat-denatured tropomyosin, without being affected by food matrices. These results indicated that this ELISA is highly specific to crustacean tropomyosin, and will be useful as a method for detecting crustacean allergens in processed food products.

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We evaluated the effects of apple polyphenol (AP), of which the major components are procyanidins, on obesity and glucose tolerance using Zucker fatty rats (fa/fa). In this study, Zucker fatty rats were fed diets containing 0.2% or 1.0% apple polyphenol for 12 weeks. Visceral fat weight and triglyceride levels in blood and liver were reduced by AP intake. Glucose and insulin levels in blood also decreased, and the amount of fatty acids excreted into feces increased in dose-dependent manner. Furthermore, suppression of fatty acid synthase gene expression in the liver and increase of adiponectin gene expression in white adipose tissues were observed. These results indicate that AP improves lipid metabolism and insulin resistance.

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Soybean seeds were collected from 5 sites in Japan (20 cultivars, 31 samples), and the quantities of isoflavone, thiamine (vitamin B1), riboflavin (vitamin B2) and tocopherol (vitamin E) were determined. Of the analyzed elements, isoflavone and α-tocopherol equivalent tended to change greatly among the sample seeds. Total isoflavone content ranged from 131.6 to 568.7mg/100g DW in the whole samples, and the mean value was 302.9mg/100g DW. The coefficient of variation was 40.7%. For each site, total isoflavone content tended to change more than other elements, so that isoflavone appears to be easily influenced by the growing conditions of cultivars. α-tocopherol equivalent ranged from 3.4 to 13.3mg/100g DW, with a mean value 5.6mg/100g DW, and coefficient of variation of 40.5%. In soybean seeds, changes in α- and β-tocopherol were large, and the nutritional value of soybeans as a source of vitamin E was greatly influenced by changes in α-tocopherol content. The coefficient of variation for thiamine and riboflavin were 13.0 and 10.3%, respectively, and their variation was smaller than isoflavone or α-tocopherol equivalent. Samples of soybean cultivar Fukuyutaka were collected from 11 sites in Kyushu, and the same analyses were conducted to investigate the influence of growing location. Results obtained were similar to those of the soybeans from all 5 sites. In conclusion, the selection of soybean type seems to be important when isoflavone or vitamin E is the purpose of soy food production.

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Starch content affects the taste, method of cooking and processing of potato tubers, and varies widely under different growing conditions. In order to enable the introduction of sorting machines based on the starch content of potato tubers, we investigated nondestructive determination of starch content using visible and near-infrared (NIR) spectroscopy under practical conditions. Potatoes were placed on a conveyor system and a photometric sensor was continuously applied. Using potato tubers of various sizes and varieties, partial least squares (PLS) regression was carried out relative to starch content as measured by specific gravity to the second derivative spectra. The standard error of prediction (SEP) for starch content of ‘Danshaku-imo’, ‘Mayqueen’ and ‘Kita-akari’ varieties were 0.87%, 0.58% and 0.86%, respectively. Accuracy of prediction was slightly affected by differences in growing locations, by mud adhering to tuber surfaces, and by the temperature of tubers. It is concluded that the visible and NIR transmittance method is effective for accurate and rapid selection of potato tubers based on starch content and could thus be used in packinghouses.

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[in Japanese]

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