In this study, to improve the reliability of identifying natto bacteria strains isolated from natto all over Japan, the effectiveness of a pretreatment, using an ethanol-formic acid treatment, in identifying and distinguishing the natto bacteria strains using MALDI-TOF MS was investigated. Samples pretreated with the direct coating-matrix treatment, which is the manufacturer's recommended pretreatment method, were subjected to MALDI-TOF MS and identified using an existing database. As a result, it was difficult to accurately identify the strains of the B. subtilis groups including the isolates from natto. Therefore, it was necessary to construct an original database to improve the reliability of identifying natto bacteria strains isolated from natto. To improve the accuracy of their analysis, the MALDI-TOF MS analysis was performed with the ethanol-formic acid treatment as the pretreatment. In a dendrogram that was constructed based on the mass spectral data obtained, strains isolated from natto formed independent clusters distinct from other species of the B. subtilis group. Furthermore, the mass spectra obtained for the strains isolated from natto were characteristic of "B. subtilis subsp. natto", which is different from those obtained for other B. subtilis groups.

　The aim of the present study is to clarify the influence of the difference in acidity of the fruits and the storage temperature on the citrus fruit 'Shiranuhi'. Sugar content, acidity and organic acid contents decreased significantly during storage, and the fruits stored at lower temperature had a tendency to keep higher levels than the fruits stored at higher temperature. On the other hand, the fruits with high acidity kept higher levels than the fruits with moderate acidity. Sucrose content increased slightly during storage, while glucose and fructose content decreased. The fruits stored at lower temperature had a tendency to keep higher contents than the fruits stored at higher temperature in a similar manner as above. Little change in content of l-ascorbic acid was observed during storage although there was a decrease in dehydroascorbic acid. Although most of the scores from sensory evaluation of the fruits decreased during storage, the fruits with high acidity (ca. 1.1%) stored at 7℃ kept the highest sensory properties. As conclusion, it was revealed that the fruits with high acidity (ca. 1.1%) stored at 7℃were kept their quality for 4 to 5 months.

　Egg white products dry-heated at neutral and alkaline pH are used as texture modifiers owing to their different gelling properties. In this study, we investigated the soluble protein aggregate (SPA) characteristics and gelling properties of neutral and alkaline dry-heated egg whites (NDEW and ADEW, respectively) with equal protein surface hydrophobicity. ADEW has a lower molecular weight SPA crosslinked by more lysinoalanine and lanthionine bonds than NDEW, indicating that the SPA in ADEW has a higher crosslink density than that in NDEW. Anion-exchange high-performance liquid chromatography followed by polyacrylamide gel electrophoresis revealed that the SPA surface was strongly negatively-charged in ADEW. Moreover, NDEW gel with a fibril structure was harder than ADEW gel with dispersed small aggregates. These results suggest that the molecular weight, crosslink density, and surface negative charge of the SPA vary depending on the pH during dry-heat treatment and are key factors determining the gel textures of NDEW and ADEW.