The mixed grain koji “Jukoku Koji” is produced by fermentation with either white koji mold (Aspergillus kawachii), black koji mold (Aspergillus awamori) or yellow koji mold (Aspergillus oryzae) of a mixture of 9 types of grains (white rice, Hordeum vulgare, red rice, brown rice, Setaria italica, Panicum miliaceum, black rice, Sorghum bicolor, Japanese barnyard millet). In this study, the effect of “Jukoku Koji” on protein digestion was investigated in rats using the portal vein catheter placement method. First, “Jukoku Koji” and a casein solution were incubated at 37ºC and the released amino acids were quantified by HPLC with OPA pre-column derivatization. The results showed that the concentration of amino acids (leucine, valine, histidine, methionine, phenylalanine and tyrosine) increased over time. Furthermore, when “Jukoku Koji” was administered to rats received a continuous intragastric infusion of casein solution, portal vein blood concentrations of free amino acids (leucine, isoleucine, valine, methionine, phenylalanine, alanine, asparagine, glutamine, glutamic acid, tyrosine and serine) were significantly greater than the control group (casein administered group). The results suggest that “Jukoku Koji” promotes protein digestion in rats.

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In this study, we examined the characteristics of flavonoids, courmarins, and synephrine in sudaidai and hetsukadaidai, the sour citrus fruits of local special products. The contents of the compounds in juice and peel of sudaidai (scientific name unclear), hetsukadaidai (unclear), daidai (Citrus aurantium) and natsudaidai (Citrus natsudaidai) were determined using HPLC, and the quantitative values were analyzed using principal component analysis. The characteristics of the compounds in the juice and peel of sudaidai resembled those of daidai, and those of hetsukadaidai were different from those of daidai and natsudaidai, based on the scatter diagrams of the score plots. The scientific name of sudaidai was suggested to be the same as daidai (Citrus aurantium). Auraptene, an antitumor compound, was found in the peel of hetsukadaidai, although it was not found in daidai and occurred at lower content than in natsudaidai. It was abundant in the flavedo (epicarp) of hetsukadaidai. Synephrine, an adrenergic phenethylamine, was found in sudaidai at level comparable with that in daidai, although it was found at lower content in hetsukadaidai than in daidai. The antioxidative activity of the peel and juice of daidai and sudaidai was significantly higher than that of hetsukadaidai and natsudaidai (p<0.05). The activity of the albedo (mesocarp) of hetsukadaidai was significantly higher than other regions of the fruit (p<0.05). The activity was shown to have a positive correlation with the content of the antioxidant neoeriocitrin and the correlation coefficient (R) was high (R>0.9).

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Fag e 1 is a 22 kDa globulin found in common buckwheat (Fagopyrum esculentum) and it is known to be one of the major allergens causing severe allergic symptoms. In this study, we successfully obtained recombinant Fag e 1 using the Pichia expression system and prepared an allergen-specific hypoallergenic agent by the controlled dry-heating phosphorylation of Fag e 1 (P-Fag e 1). Then, we investigated if P-Fag e 1 can be useful as an immunomodulator in Fag e 1-sensitized mice. For this, P-Fag e 1 was orally administrated into Fag e 1-sensitized mice for 6 weeks, and then these mice were challenged with Fag e 1. We observed a significant reduction in the histamine release in addition to diminished production of total as well as specific IgE in the P-Fag e 1-treated mice. In contrast, total IgA level increased by the treatment with P-Fag e1. The levels of the IL-4 cytokines from both spleen and Peyer’s patches were significantly decreased in P-Fag e 1 treated mice. Additionally, the population of T follicular helper cells (Tfh cells) was increased in the P-Fag e 1 treated group. The suppression of IgE production in the Fag e1 treated group might be due to the enrichment of the Tfh cells and IgA production. Therefore, it could be proposed that P-Fag e 1 is an allergen-specific immunomodulator in mice allergic to Fag e 1.

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Yellowtail Seriola quinqueradiata fed a diet supplemented with powdered olive Olea europaea leaves is a popularly cultured fish with the registered trademark of “olive yellowtail (OY)”. Water-soluble low molecular weight compounds in OY muscles were determined by non-target metabolome analysis and the results were compared with the compounds in muscles of control yellowtail fed a diet without powdered olive leaves (CtY). The metabolome analysis showed some differences in the levels of amino acids, organic acids, sugar alcohols, and so on between OY and CtY. OY had higher levels of sweet-tasting compounds, serine, glycine, and glycerol than CtY, supporting our previous report that OY is distinct from CtY in the taste, especially sweet taste (Oyama, 2017). Antioxidant capacities of water-soluble compounds extracted from muscles of OY and CtY were determined by hydrophilicoxygen radical absorbance capacity (H-ORAC) method. Although antioxidant capacity of dark muscle showed no significant difference between the two fishes, the results for ordinary muscles showed that OY had 1.36 times higher antioxidant capacity than CtY, which is probably due to higher level of ascorbic acid (1.53 times high). These results suggest that feeding olive leaves endows muscle with enhanced taste and antioxidant capacity by altering metabolite profiling of muscles.

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Caffeine, a common food component, is not banned or restricted in Japan. The ready availability of caffeine-containing products, such as coffee, often leads to excessive consumption that can be associated with caffeine intoxication, as described in numerous reports. We measured the caffeine content of coffee, a major contributor to caffeine intake, with a particular focus on single-serve take-out products sold at convenience stores, coffee shops, and fast-food chains nationwide. As the results, the caffeine content (0.72 ± 0.03 to 1.01 ± 0.04 mg/mL) was higher than the reference value (0.60 mg/mL) presented in the Standard Tables of Food Composition in Japan, and the values varied markedly among the products. Additionally, there was considerable variability in the caffeine concentration even among samples of the same product, with values ranging from 0.56 to 0.83 (mean, 0.74 ± 0.09) mg/mL (n=8).

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We have developed and evaluated a method for quantifying chloroacetic acids (monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid) in mineral water (MW) products. After a performance evaluation, we surveyed the chloroacetic acids concentrations in 150 kinds of MW products purchased on the Japanese market in 2016. The recovery rates of chloroacetic acids from the 150 spiked samples prepared from purchased MW products ranged from 90% to 110%. These results suggest that the analytical method is highly applicable to MW products. Monochloroacetic acid (MCAA) was identified in three different samples at a detection rate of 2.0%; dichloroacetic acid (DCAA) in seven different samples at a detection rate of 4.7%, and trichloroacetic acid (TCAA) in one sample at a detection rate of 0.7%. No product was found to have a chloroacetic acid level that exceeded the World Health Organization guidelines for drinking-water quality (MCAA: 0.02 mg/L, DCAA: 0.05 mg/L, and TCAA: 0.2 mg/L).

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