For Omphalotus japonicus, the coloring molecule was found and characterized using a simple method of identification with a color reaction. The compound that chang color under basic conditions was isolated from a methanolic extract of O. japonicus by liquid–liquid extraction. That compound was identified as thelephoric acid by various spectrum analyses. Color reaction by a beam reagent (5 w/v% potassium hydroxide ethanolic solution) and UV-Vis absorption of an ethanolic solution of thelephoric acid coincided with those of an ethanolic extract of O. japonicus. We conducted LC-MS/MS analyses of all four mushroom species (O. japonicus, Sarcomyxa serotina, Pleurotus ostreatus, and Lentinula edodes). Results demonstrated that thelephoric acid was detected only in O. japonicus. These findings indicate thelephoric acid as a coloring molecule for the identification method described above. This method is useful for distinguishing O. japonicus among other edible mushrooms having similar appearance.

Multilayer laminated films are widely used as food packaging materials. The substances contained in these films have the potential to migrate into food in contact, but the actual situation is unknown. In this study, we first determined the contents of 24 elements in 42 food laminate bags by ICP-OES and ICP-MS. As a result, 17 elements (Na, Mg, Al, P, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Sr, Sn, Sb and Pb) were detected, whereas seven (K, Ni, Ge, As, Ag, Cd and Ba) were below the limits of quantification (LOQs). The detected elements were probably derived from such as impurities in the aluminum layer, metal catalysts, pigments and adhesives. Next, migration tests were performed in 14 of these samples using two types of food simulants (distilled water and 4% acetic acid). The maximum migration levels of Sb, Sn, and Al were 0.11, 5.5 and 74.8 ng/mL, respectively, and the other elements were below the LOQs. It was suggested that Sb and Sn may have migrated from the non-food contact layer.

A method for analyzing tetrodotoxin (TTX) in miso soup samples was proposed. The samples were purified using strong cation exchange solid-phase extraction and analyzed by liquid chromatography–tandem mass spectrometry. The recovery of TTX was considerably influenced by the salt concentration in the loading solution during purification. It was observed that diluting the loading solution to reduce the salt concentration helped to maintain the recovery rate during the washing step. However, during the loading step, the benefit of dilution in improving recovery was not evident, as the enhanced retention on the solid phase caused by dilution was counteracted by losing TTX with the increased volume of the loading solution, which led to enhanced elution. This suggests that the volume of extraction solution used in the loading process is crucial in determining the recovery rate. Additionally, the use of volatile ammonium acetate as the elution solvent was explored to optimize conditions for effective recovery. Testing this method on miso soup samples with varying miso types, salt concentrations, and TTX levels resulted in consistently high recovery rates of>80%.

Some microorganisms, including lactic acid bacteria (LAB), can bind to mycotoxins. Its binding ability is useful for mycotoxin mitigation. Conventionally, the binding assay for this ability of microorganisms to mycotoxins has been performed by the so-called in vitro assay. We previously reported that Lactococcus lactis isolated from cucumber had the ability to bind to aflatoxins using the in vitro assay., However, this is an indirect method by which binding ability is estimated from the mycotoxin residue in supernatant after some processes such as mix, incubation, and centrifugation and it takes time. In the present study, we developed a direct and rapid assay to assess their binding ability using a surface plasmon resonance imaging (SPRi) instrument. It could observe the binding ability as a visual image in real time. The efficacy of this SPRi assay was compared with the in vitro assay. Aflatoxin M₁-bovine serum albumin conjugate (AFM₁-BSA) and deoxynivalenol-BSA conjugate (DON-BSA) were immobilized on the surface of the sensor prism in SPRi assay. The above L. lactis was used to prove the binding ability to the aflatoxin. In vitro assay showed that the binding ratio to AFM₁ was higher than that to DON in both live bacterial cells and heated cells. In the SPRi assay, the binding of live cells to AFM₁ was confirmed by % of the refractivity change (%ΔR) and visual imaging in real-time. The %ΔR of DON was poor, and no visual image was recognized. On the other hand, the heated cells did not bind to any mycotoxins. The results indicate that the SPRi assay can monitor the binding ability of live cells more rapidly and simpler than in vitro assay. It would be a useful tool for the selection of beneficial mycotoxin-detoxifying LAB.

The level of radioactive cesium in food that is generally consumed in the rehydrated state can be calculated from measurements taken in the dried state using the specific weight change rate set by the Ministry of Health, Labour and Welfare. However, only a few dried foods have a specified weight change rate. Accurate specific weight change rates are critical in determining the compliance of a dried food item with Japanese maximum limits (JMLs) for radioactivity. We investigated the weight change rate of dried to rehydrated kotake mushrooms, which may contain relatively high concentrations of radioactive cesium and whose weight change rate has a large effect on the judgment of JML compliance. The average weight change rate of dried kotake mushrooms was 5.7 (range: 4.2 to 6.9), which was 1.4 times larger than the currently applied weight change rate of 4.0. Since the minimum weight change rate was 4.2 in this study, it was considered that the weight change rate currently applied to dried kotake mushrooms was a reasonable value. Further data is required in order to set specified weight change rates and to evaluate the validity of currently applied weight change rates in dried kotake mushroom.

In this study, a rapid and accurate analytical method was developed for the simultaneous determination of 26 plant toxins and 11 mushroom toxins in toxic plants, toxic mushrooms, and their cooked products using LC-MS/MS. This method enables highly selective detection of all 37 analytes, including those with high polarity and low molecular weight, within 10 min using Scherzo SS-C18 column. The analytes were extracted from the samples using methanol and trichloroacetic acid, and purified using Captiva EMR-Lipid. A 50 vol% methanol solution was used as the test solvent, to minimize matrix effects. Validation with six types of food samples demonstrated recoveries ranging from 56.0% to 180.5% (with 96% or more of analytes achieving 70–120%) and RSD of 16.0% or less (with 98% or more of analytes achieving 10% or less), at an added concentration of 1 mg/kg. These results indicate that this method is effective for health crisis management. Additionally, the method successfully detected expected toxins in food leftovers and reference products implicated in previous health hazard cases.

Thiouracil (2-thiouracil) is a thyrostat used to promote weight gain in cattle. However, its use is prohibited within the European Union (EU), necessitating the monitoring of its presence in bovine urine for beef exports to the EU. In this study, we present the development and validation of a quantitative method for the determination of 2-thiouracil, 4-thiouracil, and 6-methyl-2-thiouracil in bovine urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method involves stabilizing the analytes by adding hydrochloric acid and ethylenediaminetetraacetic acid to the sample, followed by derivatization with 3-iodobenzyl bromide, cleanup with a divinylbenzene-N-vinylpyrrolidone copolymer cartridge, and subsequent LC-MS/MS analysis. The developed method was validated for determination of 2-thiouracil, 4-thiouracil, and 6-methyl-2-thiouracil in bovine urine at a concentration of 10 μg/L. The trueness ranged from 94 to 97%, with intra-day precisions below 5% and inter-day precisions below 8%. No chromatographic interference was observed near the analytes’ retention times. This analytical method is particularly valuable because it can determine whether 2-thiouracil was illicitly administered or ingested via feed containing plants of the Brassicaceae family, by confirming the presence of 6-methyl-2-thiouracil or 4-thiouracil alongside 2-thiouracil in bovine urine.