The food colourants copper chlorophyll (CuCh) and sodium copper chlorophyllin (CuCh-Na) are used worldwide in a wide range of processed foods. We developed an analytical method for the determination of CuCh/CuCh-Na levels in processed foods to effectively monitor the appropriate use of these colourants. The proposed analytical method involves simultaneous extraction and parallel analysis of hydrophobic CuCh and hydrophilic CuCh-Na without potentially harmful solvents. CuCh/CuCh-Na were extracted from processed foods with 1-butanol and ethyl acetate. CuCh-Na was extracted from the initial extraction solvent with 0.15 mol/L NaOH, and then the residual extraction solvent and alkaline water layers were dried. Finally, the samples were carbonized with H₂SO₄. The carbonized samples were ashed in a muffle furnace at 480°C. The residue was dissolved in 0.1 mol/L HNO₃, and the level of copper in the samples was determined using atomic absorption spectrophotometry to indirectly quantify the levels of CuCh and CuCh-Na. Recoveries of CuCh and CuCh-Na from spiked samples were in the range of 70.7%-80.8% and 55.6%-72.3% (except for white chocolate, at 50%), respectively, with standard deviations in the range of 1.7%-5.0% and 1.5%-7.8%, respectively. In commercial processed foods, the levels of CuCh and CuCh-Na ranged from ND (not detected) to 3.7 mg/kg and from ND to 8.0 mg/kg as copper, respectively.

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We analyzed the chemical constituents of Pacific oysters (Crassostrea gigas) collected in the Konagai district in Nagasaki Prefecture and further evaluated the taste characteristics using a taste-sensing system. We compared the results with those obtained for oysters collected in Hiroshima Prefecture, which are most widely distributed oysters in Japan. We analyzed the taste components, including free amino acids, adenosine triphosphate (ATP) and related compounds, and glycogen contents, in the oysters by means of spectroscopy and high-performance liquid chromatography (HPLC). The levels of serine, alanine, and β-alanine, which are free amino acids that confer sweetness, were significantly higher in oysters cultured in Konagai than those cultured in Hiroshima. Glutamic acid levels were not significantly different between oysters from the two districts. Oysters in Konagai contained significantly lower levels of aspartic acid, which is associated with a slight umami taste, than those in Hiroshima. The levels of valine, methionine, isoleucine, leucine, and phenylalanine, which are associated with bitterness, were significantly lower in oysters from Konagai than in those from Hiroshima, although the overall proportion of these amino acids among the total free amino acids was low. No significant difference in total free amino acid levels and glycogen levels was observed between the oysters cultured in the two districts. With regard to ATP and its related compounds, adenosine mono-phosphate (AMP) levels were shown to be significantly higher in oysters from Konagai than in those from Hiroshima. The results of the taste sensor analysis showed significantly higher values of umami and astringency, with significantly lower values of aftertaste of bitterness, in Konagai samples than in Hiroshima samples. The umami taste, which is primarily derived from glutamic acid, is known to be enhanced by the synergic effect of inosine mono-phosphate (IMP) and AMP, which is structurally similar to IMP. Thus, the taste sensor used in this study might reflect the umami taste enhanced by the synergic effects on the human tongue. These findings indicate that the oysters collected in Konagai might have a stronger sweet, astringent, and umami taste and a weaker aftertaste of bitterness than those from Hiroshima. The results of the taste sensor analysis did not contradict with those of the chemical analysis. The use of a taste-sensing system to evaluate the taste of raw oysters may serve as a potential alternative to the conventional evaluation of heated oysters that are deemed more hygienic.

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The 24 kDa protein (Fag e 1) in buckwheat is considered to be one of its major allergens. The purpose of this study is to investigate the immunomodulatory effects of hypoallergenic Fag e 1 prepared by glycation with polysaccharide on mucosal allergenic responses in mice. Mannan-type-polysaccharide such as galactomannan (GalM), konjac glucomannan (KGM), and yeast glucomannan (YGM) showed attenuation of IL-4 and IL-17 production and elevation of IL-10 in cultured Peyer’s patch (PP) cells. The conjugate of Fag e 1 with GalM, KGM, or YGM was prepared using naturally occurring Maillard-type glycosylation. Dietary administration with Fag e 1-YGM conjugate for 8 weeks induced a significant reduction in Fag e 1-specific IgE and IgG1 levels and elevation in IgA level in sera and PP cells. A decrease in IL-4 and IL-17 and increase in IL-10 in PP cells were observed in the group of Fag e 1-YGM conjugate. Differentiation ratio of regulatory T cells (Treg) and T follicular helper cells in PP increased by feeding with Fag e 1-YGM conjugate. These suggest that Fag e 1-YGM conjugate could be contribute to the development of an immunomodulatory hypoallergenic agent for buckwheat allergy.

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The temperature of migration solutions on the preparation of a test solution for migration tests of food-contact products was monitored using a temperature data logger under several heating conditions. Temperature transitions of the solutions heated via four types of water baths set at 60ºC were similar, and the temperature increased with time reaching 60ºC ± 2ºC after heating for 15 min. On the other hand, the temperature increase of the solutions heated using drying ovens was slower than that heated by water baths, and in some cases, the temperature did not reach 60ºC ± 2ºC. Furthermore, the temperature differed according to the drying ovens and the position in the oven. The temperature of the migration solutions by the total immersion method performed at 60ºC for 30 min using water baths and drying ovens temporarily decreased to 56.5ºC–58.0ºC after applying the samples into the solution. Further, the temperature increased rapidly and was maintained at 60ºC ± 2ºC using a water bath set at 60ºC. The temperature increase of the solutions heated using drying ovens set at 60ºC was slower and reached 60ºC ± 2ºC after heating for more than 15 min. However, it was maintained at 60ºC ± 2ºC using a drying oven set at 65ºC, and it was also maintained using a drying oven set at 60ºC when the migration solution preheated at 65ºC was used. The temperature of the migration solution by the total immersion method performed at 95ºC also temporarily decreased to 85.8ºC–90.9ºC after applying the samples into the solution. However, the temperature was maintained at 95ºC ± 5ºC using a water bath set at 95ºC and drying ovens set at 105ºC, 110ºC, and 115ºC. On the other hand, the temperature of the migration solution by the single surface testing performed at 60ºC decreased considerably to 44.4ºC–51.3ºC upon pouring the migration solution into a single surface migration vessel and did not reach 60ºC ± 2ºC after heating for more than 20 min. However, by heating the single surface migration vessel at 60ºC before pouring the migration solution into the vessel, the temperature slightly decreased to 59.1ºC–59.7ºC and was maintained at 60ºC ± 2ºC using a water bath set at 60ºC and a drying oven set at 70ºC. The temperature of the migration solution using the single surface testing performed at 95ºC also decreased to 89.2ºC–90.1ºC upon pouring the migration solution into the vessel with preliminary heating at 95ºC. Subsequently, the temperature was maintained at 95ºC ± 5ºC using a water bath set at 95ºC or a drying oven set at 115ºC. Migration tests into 4% acetic acid by the total immersion method were performed using two rubber gloves, and the resulting total evaporation residue levels and the migration levels of zinc and calcium were compared under several heating conditions. No significant differences in their migration levels were observed in the cases where the migration solution temperatures were maintained within 60ºC ± 2ºC or 95ºC ± 5ºC.

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Buckwheat allergy has been recognized as a common food allergy with increasing consumption of the crop. It is considered to be one of the leading causes of food anaphylaxis. In this study, we prepared the hypoallergenic buckwheat proteins using the naturally occurring Maillard-type glycosylation and investigated their effect on immune response of spleen cells. Whole buckwheat proteins (WBP) was glycosylated with 40 kDa dextrans (DX40) under the controlled dry-heating at 65°C and RH79 for 2 weeks. The resulting conjugates of WBP and DX40 (WBP-DX40) decreased the ratio of MHC class II/CD86 double-positive cells compared to control. WBP-DX40 further decreased the levels of Th2-related cytokines such as IL-4 and IL-10 in the spleen cells and did not affect the secretion level of IFN-γ. These results suggest that the attachment of DX40 to WBP induces the suppression of Th2- immune response against buckwheat proteins.

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Recently, consumers have a heightened awareness of food safety; moreover, complaints regarding off-flavor are also increasing. There are various causes of off-flavor in frozen food, but in our experience there have been repeated cases in which p-DCB detected in residential environments and styrene detected in refrigerators have been detected in food that has generated complaints of off-flavor. Therefore, we consider that these compounds might pertain to off-flavor in frozen food products. Also, testing has been done on the migration of volatile organic compounds (VOCs) to food at room temperature up to now. On the other hand, there is no knowledge regarding frozen food. In this study we investigated VOCs and monitored the amount of migration regarding p-DCB and styrene in home freezers for an extended period. The results showed that p-DCB and styrene have existed in all of the home freezers examined, and both substances have migrated to frozen food. For this reason, it is possible that both of these substances are indicators of lingering odors when keeping food refrigerated. Therefore, it was shown that the amount of migration varies according to the type of food and how packages of food are resealed once opened. These observations indicate that frozen food whose packages were opened has a risk of lingering odors the same as food stored in other temperature zones does.

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Concentrations of Cs-134 and Cs-137 in 205 wild mushroom samples collected in Yamanashi Prefecture from September 2011 to October 2013 were measured. In all of wild mushroom samples, the concentration of Cs-137 was higher than that of Cs-134; in some samples, Cs-137 was detected while no Cs-134 was detected. Even when the concentrations of Cs-134 and Cs-137 were compared in consideration of their half-lives on the assumption that these radioactive cesium elements were brought due to the Fukushima Daiichi Nuclear Power Plant (NPP) accident, the concentration of Cs-137 was still significantly higher than that of Cs- 134. As the amounts of Cs-134 and Cs-137 released from the Fukushima Daiichi NPP were almost equivalent, the finding indicates that the collected wild mushrooms contained Cs-137 not derived from the Fukushima Daiichi NPP accident. In fact, the maximum concentration of Cs-137 not derived from the NPP accident was more than 200 Bq/kg in a sample.

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The precipitation during wheat anthesis can result in Fusarium head blight (FHB) in the ear of wheat and causes not only yield loss of grains but also mycotoxin accumulation in grains. Zearalenone is one of the major Fusarium toxins and known as an estrogenic mycotoxin. To assess the retention of zearalenone in processed foods of wheat, a patent flour sample prepared from Fusarium-damaged Japanese soft wheat was subjected to noodle cooking, and the contents of zearalenone before and after cooking were analyzed. The contents of zearalenone in raw noodle, boiled noodle, and broth were determined using an in-house validated analytical method with multifunctional cartridge clean-up and HPLC-fluorescence detection. In this sample, the substantial retention of zearalenone in the boiled noodle was 83%. More than two-times as much distribution of zearalenone as that in broth was observed in boiled noodle. As a result, it was shown that boiling was not effective to remove zearalenone from raw noodle.

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