Simultaneous analysis was examined for eight types of preservatives, benzoic acid, sorbic acid, dehydroacetic acid, ethyl p-hydroxybenzoate, isopropyl p-hydroxybenzoate, propyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate and butyl p-hydroxybenzoate, in foods by liquid chromatography after solvent extraction and solid-phase purification. Recovery tests using four types of food showed good results with recovery rates of 92 to 110%, repeatability RSD of 1.2 to 7.0%, and laboratory reproducibility RSD of 2.6 to 9.5%.

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Public perceptions are significantly more concerned about agricultural chemicals including pesticides, feed additives, and animal drugs than food safety experts. To address these perceptions, we estimated the mean daily intake of 28 agricultural chemicals across the entire Japanese population (≥ 1 year old) using the total diet samples based on the market basket method (14 food groups). The survey was conducted with the collaboration of six local government research institutes (Hokkaido, Tohoku, Kanto, Kansai, Chugoku, and Kyushu) from 2019 to 2021. The estimation of the mean daily intake of residual agricultural chemicals through the consumption of each food group was calculated by multiplying the concentration in the respective food group by the daily food consumption. The highest ratio of estimated daily intake over acceptable daily intake was observed for acephate (0.39%). The contribution rates from crops were higher than those from livestock and aquatic products for many agricultural chemicals. Our results show that all of agricultural chemicals evaluated in this study were far below the ADIs, and these findings considered to be useful to bridge the perception gap.

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Roasted green tea (RGT) has a unique flavor and aroma, which exhibits a relaxing effect. Few reports have elucidated the relaxing effect and other biological activities of RGT. Therefore, this study aimed to evaluate the neuroscientific functions of pyrazines, pyroglutamic acid, and epimerized catechins, which are produced during the roasting process in the manufacture of RGT. Pyrazines served as modulators of the ionotropic γ-aminobutyric acid receptor (GABA_AR), the inhibitory neurotransmitter receptor of the brain, in the Xenopus oocyte expression system. This was further confirmed by the elevated plus maze test. Pyroglutamic acid served as an agonist of GABA_AR. Gallocatechin gallate epimerized catechin during roasting, resulting in a compound with the same antioxidant effect on the human neuroblastoma cell line SK-N-SH against H₂O₂ as epigallocatechin gallate, a catechin before epimerization. These characteristic compounds could be responsible for the biological effects of RGT.

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In this study, we validate the use of a HPLC method, which is listed as the confirmation test for sulfur dioxide (SO₂) and sulfites in the notification, “Analytical Methods for Food Additives in Foods” by the Ministry of Health, Labour and Welfare in Japan, as a quantitative method. Moreover, the stability of aqueous 1% triethanolamine (tris(2-hydroxyethyl)amine: TEA) SO₂ solution with several concentrations was tested. The results revealed that the long-term (1 year) stability at 5℃ was favorable under the concentration of 1,000 µg/mL with the range of 0.1-20 µg/mL, which are normally used for standard stock and calibration solutions, respectively. Conversely, the high-concentration standard solutions (10,000 and 20,000 µg/mL), usually used in spike tests around the upper acceptable limit, are unstable even after 3 days of storage at 5℃, suggesting that such solutions must be prepared at the time of their use. Furthermore, recovery tests conducted by spiking an SO₂ solution equivalent to the upper acceptable limits to eight types of food showed the HPLC method was applicable for quantification. Thus, their recovery range was 86.9%-95.6% and their RSD of repeatability and intra-laboratory reproducibility were 1.7%-4.6% and 2.4%-6.9%, respectively. These results suggest that the HPLC method is useful for quantitative analysis of SO₂ in foods during daily inspections.

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