We developed a novel ELISA kit for egg detection in accordance with the official Japanese method for extraction (official extraction method), which is used for monitoring the appropriateness of food product labeling in Japan. The monoclonal antibody used in the kit was prepared using reduced and carboxymethylated chicken ovalbumin as an immunizing antigen. The newly developed ELISA kit detected egg white solubilized in 2-mercaptoethanol and sodium dodecyl sulfate, which is used in the official extraction method. The detectable range of egg protein concentrations was 0.8-50.0 ng/mL (equivalent to 0.3-20.0 μg/g food). Cross-reactivity with both duck and Japanese quail egg was observed, but not with other food ingredients. Spike recovery tests using model processed foods showed that recovery ranged from 73.6 %-118.0 %, and intra- and inter-assay coefficients of variation were less than 6.0 % and 9.1 %, respectively. Based on the official extraction method for quantitative analysis of egg in specified food ingredients, these results suggest that a simple, monoclonal antibody-based ELISA kit is as effective as the conventional method for egg detection.

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The combined effects of water activity (a_w) and smoke compounds on the growth of Listeria monocytogenes in raw ham were investigated in five laboratories using raw ham inoculated with L. monocytogenes ATCC 49594 (serotype 4b, Scott A). L. monocytogenes grew in raw ham with a_w of 0.94 during storage at 10°C for 56 days under anaerobic conditions ; however, it did not grow at a_w of 0.92. L. monocytogenes did not grow in smoked or liquid-smoked raw ham with a_w of 0.94 in any of the laboratories. The growth inhibition of L. monocytogenes in raw ham with a_w of 0.94 was observed at a phenol concentration ranging from 0.6 to 12.2 ppm. These results suggest that the proliferation of L. monocytogenes is rather low in smoked domestic raw ham with a_w of ≤0.92 or in smoked raw ham with a_w of ≤0.94.

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Salt (3 % NaCl)-ground meats composed of frozen surimi of arabesque greenling (AG) or walleye pollack (WP), both with/without the addition of 3 % albumen powder (Al) were heated at 90°C for 30 min, both with/without preheating at 25°C for different periods. The heated gels were solubilized in various solvents by stirring for 48 hours. Protein solubility was determined and discussed in relation to the rheological properties of the heated gels.
(1) Large amounts of protein in the unset gels (directly heated gels from AG/WP and two-step heated gels from AG, both with/without Al) were solubilized in a solvent containing 0.6 M NaCl+8.0 M urea+2 % mercaptoethanol.
(2) The protein solubility of the set gels (two-step heated gel from WP, both with/without Al) in solvents containing 0.6 M NaCl+1.5 M urea, 0.6 M NaCl+8.0 M urea, and 0.6 M NaCl+8.0 M urea+2 % mercaptoethanol decreased greatly and insoluble proteins accumulated in the gel structure with the progress of preheating. (3) The rate of protein solubility suggested that hydrophobic interaction was strongly related to the rheological properties of the unset gels (and S-S bonding was slightly associated with the addition of Al), whereas a more intensive bonding/interaction was predominantly involved in that of the set gels.

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Hot air drying is a conventional method for producing dried fruit ; however, hardening and browning of the fruit pulp surface often occur during processing. The objective of this study was to produce a high quality semi-dried Japanese pear fruit using a simple method based on hot air drying. We found that microwave irradiation of Japanese pear pulp followed by hot air drying produced semi-dried fruit with uniform softness and a vivid yellow-orange color. Microwave pretreatment shortened the hot air drying period by one-third. For optimized processing, the time required for microwave irradiation of Japanese pear pulp was proportional to pulp weight and inversely proportional to irradiation power. Based on overall sensory evaluation by consumers, including separate evaluations of appearance, taste, and texture, the semi-dried fruit obtained in this study was shown to be preferable to fruit without pretreatment. Therefore, we conclude that our novel semi-dried Japanese pear fruit is a promising food item due to its color and texture. Furthermore, the simple production process we developed in this study can be easily adopted by the food industry.

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The effect of noodle size and boiling time on dynamics of radioactive cesium during cooking of Japanese udon noodles was investigated. Two noodle sizes, thick noodles (2.5 mm × 3 mm) and thin noodles (1.5 mm × 1.5 mm), were prepared and processing factor (Pf, ratio of radioactive cesium concentration in processed materials to raw materials, calculated by [concentration of boiled noodles (Bq/kg)/concentration of raw noodles (Bq/kg)]) and food processing retention factor (Fr, ratio of residual radioactive cesium content in processed materials to raw materials, calculated by [radioactive cesium content of boiled noodles (Bq)/radioactive cesium content of raw noodles (Bq)] ) at various boiling times were calculated. Both Pf and Fr were significantly decreased by boiling in both noodle sizes. Prolongation of boiling time contributed to decreases in Pf and Fr in both noodle sizes, although there were no significant decreases in Pf after 20 min in thick noodles and 4.5 min in thin noodles. In Fr, there were no significant decreases after 10 min and 3 min in thick and thin noodles, respectively. These data indicate that prolongation of boiling time contributes minimally to lowering of radioactive cesium due to the low concentration gradient of radioactive cesium between boiled noodles and broth when noodles are properly boiled for consumption, 20 min and 3-4.5 min for thick and thin noodles, respectively. Thin noodles achieved lowered radioactive cesium content in a short boiling time compared to thick noodles. Greater than 80 % of radioactive cesium contained in the raw noodles was removed by boiling for the proper time in both thick and thin noodles.

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Changes in total anthocyanin, total proanthocyanidin, and γ-aminobutyric acid (GABA) contents and antioxidant capacity were investigated during the manufacture of roasted beans made from black soybean cultivar “Kurodamaru.” The contents of anthocyanin and proanthocyanidin decreased remarkably in black soybean during the water immersion process ; however, roasted beans showed contents of 53 % and 83 % on a dry matter basis, respectively, compared to raw soybeans. The GABA content of soybeans increased 5.3-fold during the immersion process, and subsequently decreased upon storage for 16 hours in a constant temperature warehouse and roasting for 20 min at 168°C. The oxygen radical absorbance capacity of roasted beans was significantly higher than that of raw soybeans (P <0.05).

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