With the aging population, the incidence of postmenopausal osteoporosis is becoming a significant health concern in Japan. From the perspective of preventive medicine, the consumption of food-based ingredients with anti-osteoporotic potential is highly anticipated. Kudzu (Pueraria lobata), a leguminous climbing plant with long vines, has been used as a traditional medicinal herb for over a thousand years in East Asia. This review summarizes the anti-osteoporotic effects of kudzu vine-derived isoflavones in　ovariectomized (OVX) mouse models and their biokinetics in vivo.

View full abstract

Histamine is produced when histidine in food is broken down by decarboxylase produced by bacteria. Since cases of histamineinduced food poisoning involving many patients in school canteens and restaurants have been reported, an analytical method for histamine that can analyze multiple samples is required. In this study, we evaluated the performance of an improved histamine quantitative assay kit using microplates and confirmed its quantitative range, accuracy, laboratory reproducibility and ruggedness. As a result of the evaluation, the improved method is applicable to histamine testing of processed fish and fish products and is a useful test method that allows multiple samples to be tested quickly and easily.

View full abstract

The migrated primary aromatic amines (PAAs) from polyamide cooking utensils on the Japanese market were examined using LCMS/MS and the origins of the detected PAAs were investigated. The migration conditions were based on EU methods, employing 3% (w/v) acetic acid as food simulants at 100°C for 2 hours. For 25 PAAs confirmed to be stable under the migration conditions, validation tests were conducted at concentrations of 2.0 μg/kg, 10 μg/kg, and 20 μg/kg. The results of the performance evaluation indicated that all PAAs met the target criteria. Using the validated method, 31 polyamide cooking utensil samples were analyzed, and 9 of them exceeded the EU regulatory limits. The most frequently detected PAAs was aniline, with concentrations ranging from 4.1 to 199.4 μg/kg in 9 samples. The highest concentration of detected PAAs was 4,4’-methylenedianiline, with a maximum detection of 1655.6 μg/kg. Other PAAs detected, excluding aniline and 4,4’-methylenedianiline, were o-toluidine, 2,4-diaminotoluene, and 3,3’-dichlorobenzidine. In this study, the detected PAAs and their trends were similar to those reported in other countries. Moreover, the origins of the detected PAAs were determined using atmospheric solid analysis probe mass spectrometry and pyrolysis gas chromatograph mass spectrometry. The analysis revealed that diphenylamine was commonly detected in several samples containing aniline, suggesting that black colorants such as aniline black (polyaniline) and nigrosine might be sources of aniline. On the other hand, it was suggested that 4,4’-methylenedianiline may have been intentionally added to the sample as a monomer.

View full abstract

A characteristic substance was isolated from a methanol extract of kumquat by preparative HPLC using a reversed-phase column. The isolated substance was identified as 3’,5’-di-C-β-glucopyranosyl phloretin (DGP) by ¹H and ¹³C NMR analyses. The antioxidative activity of DGP and phloretin, an aglycone, was measured using the 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. Phloretin exhibited higher activity than Trolox, a standard antioxidant, whereas DGP exhibited lower activity. The DGP content in four kumquat fruits was determined by HPLC and found to range from 6.1 to 10.9 mg/g dry weight (dw). The DGP content was determined as 17.4 mg/g dw in the peel, 12.8 mg/g dw in the sarcocarp, 7.8 mg/g dw in the juice, 17.9 mg/g dw in the fruit core, and 0.5 mg/g dw in the seed. The DGP content in solutions of kumquat fruit powder was analyzed by HPLC after treatment at 0 °C or 20 °C for 45 min and remained unchanged. However, the DGP content in solutions of kumquat fruit powder decreased significantly after treatment at 50 °C or 100 °C for 45 min. Processed kumquat food products, including kumquat jam and kumquat preserved in sugar, were prepared. The survival rate of DGP in kumquat jam in comparison to fresh kumquat fruit before processing was 42.1±3.2%, whereas that in preserved kumquat fruit (combination of candied fruit and syrup) was 87.6±5.6%, indicating a relatively high DGP content. This study revealed that the residual DGP content in kumquat food products depends on the processing method.

View full abstract

This study aimed to elucidate the physicochemical and sensory attributes of silken tofu prepared using optimally germinated soybean grains (OGSGs). By textural analysis, high breaking force and cohesiveness in tofu using OGSGs were observed when compared with those of tofu using non-germinated soybean grains (NGSGs), indicating tofu having higher firmness and internal cohension. Total free amino acid contents of tofu using OGSGs were approximately five times as high as those of tofu using NGSGs. Besides, the sweet, umami, and sour amino acid contents were significantly high in tofu using OGSGs. Additionally, the tofu extract using OGSGs possessed high ACE inhibitory activity. It was suggested that high ACE inhibitory activity of tofu using OGSGs was associated with its high GABA content when compared with tofu using NGSGs. These data may provide useful information for consumers and tofu-related industries to produce silken tofu with good eating quality and health-promoting benefits from OGSGs.

View full abstract

On November 13, 2007, Japan’s Ministry of Health, Labour and Welfare established an official analytical method for detecting four fungicides̶imazalil (IMZ), thiabendazole (TBZ), orthophenylphenol (OPP), and diphenyl (DP)̶on disposable chopsticks. According to this method, 20% ethanol is used as a food simulant, and disposable chopsticks are heated in this solution at 60°C for 30 min. After filtering the eluate, TBZ, OPP, and DP are analyzed using high-performance liquid chromatography (HPLC) with a fluorescence detector, while IMZ is assessed separately under different conditions using a photodiode array detector, making this process time consuming. If any of the fungicides are detected, a confirmation test is conducted using gas chromatography–mass spectrometry (GC-MS). In addition to the HPLC analysis of the chopstick eluate, the method requires a separate elution test using methanol, complicating the testing process. To address these challenges, in the current study, a solid-phase extraction column was used to purify the chopstick eluate, enabling its use for the HPLC analysis and GC-MS confirmation. Additionally, diluting the purified solution tenfold with the HPLC mobile phase containing an ion-pair reagent enhanced the DP sensitivity and quantification capability of HPLC. Overall, the proposed approach improved the quantitative analysis of fungicides on disposable chopsticks while simplifying the testing process and enhancing its reliability.

View full abstract

The “High School Curriculum Guidelines (2018 Edition)” introduced new subjects that included the term “inquiry” in their titles; for example, “Comprehensive Learning Time” was renamed “Comprehensive Inquiry Time.” This modification reflects a stronger emphasis on incorporating inquiry into learning activities than before. Japan is currently experiencing rapid population aging and declining birth rates. According to a 2024 survey on high school students’ choice of science or liberal arts pathways, only 36.4% selected science-related fields, compared to 63.6% who chose liberal arts. Consequently, fostering science-oriented talent has become a pressing challenge. On June 6, 2025, the Japanese Society of Food Chemistry also held a high school student presentation program at its 31st Annual Meeting and Scientific Conference to promote inquiry-based learning in high schools and foster the next generation of research talent. Additionally, a survey was conducted among participating society members, high school students, and teachers. The survey consisted of 5-point scale items, multiple-choice questions, and open-ended responses. Approximately 97.8% of the society members, along with all responding high school students and teachers, stated that the project was meaningful. Overall, society members’ survey responses were positive. Observing high school students sincerely engaged in research and actively presenting their work was also a positive stimulus for society members. When asked what left the strongest impression during the conference, both high school students and teachers frequently cited the “Q&A sessions and advice from participants.” Furthermore, 85.4% of high school students reported that the program gave them an opportunity to reflect on their future paths and careers, while all high school teachers stated that it helped them consider methods for guiding students in inquiry-based activities. This initiative was regarded as highly meaningful by society members, high school students, and teachers, and its continuation was considered necessary.

View full abstract