The evaporation residue test designated in the Japanese Food Sanitation Act is used to determine the total migration amount of substances that food contact materials release into foods. Vegetable oil would be the most suitable food simulant for oils and fatty foods, but it is difficult to remove by heating due to its high boiling point, so heptane and 20％ ethanol are used as substitute food simulants in the test for plastics and rubbers. The EU has introduced an overall migration test into olive oil for plastics intended to come into contact with oils and fatty foods. This test method is described in European Standard EN1186-2. However, this method has several problems. Therefore, we improved the procedures for weighing samples in a desiccator containing 43％ sulfuric acid, extraction of the absorbed vegetable oil using the soaking method with an internal standard, methyl esterification of vegetable oil using sodium methoxide, and the GC conditions for the determination of vegetable oil. The improved method is simpler and much quicker than the original method, and the harmfulness of the reagents is reduced. It can be applied to both plastics and rubbers. Comparative trials showed that the results obtained with this method and EN1186-2 method are equivalent.

A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) was developed for the determination of total amount of aflatoxin B₁, B₂, G₁ and G₂ (AFB₁, AFB₂, AFG₁ and AFG₂), using a mouse monoclonal antibody that shows similar reactivity to each of these AFs. The working range of the developed dc-ELISA was 50–230 pg/mL for AFB₁, 50–270 pg/mL for AFB₂, 60–390 pg/mL for AFG₁ and 65–700 pg/mL for AFG₂. The recovery of AFs from spiked roasted peanuts was 98％. Further, when 4 samples actually contaminated with AFB₁, AFB₂, AFG₁ and AFG₂ were examined, the results of dc-ELISA were highly correlated with the values assigned by the Food Analysis Performance Assessment Scheme. The developed dc-ELISA appears to be suitable for the determination of total AFs at concentrations around the maximum permitted level (10 μg/kg for all foods) in Japan.

Cyromazine in livestock products was determined using a validated LC-MS/MS method. There are three key points in our methods. First, the extraction was performed with two solutions, methanol and pH 3.0 McIlvaine buffer. The process was optimized for each type of sample. Secondly, cleanup was performed using a reversed-phase and strong cation exchange mixed-mode cartridge. The cartridge was washed with 0.14％ ammonium solution. Thirdly, the chromatographic separation was performed on an anion-cation exchange mode ODS column. There was no matrix effect on the extraction and determination for five livestock products. The quantification was carried out using an external standard calibration curve. This new method satisfies the Japanese guideline criteria. Recovery ranged from 77.2 to 92.1％, the relative standard deviation of repeatability （RSDr） was under 2.2％, and RSD_wr was under 6.1％. Residual cyromazine was detected in raw milks and eggs.

A LC-MS/MS-based screening method was developed for stevia sweetener in processed foods. After extraction of stevia sweetener from processed foods by dialysis, the dialysate was diluted with water, and stevia sweetener was measured by LC-MS/MS. Recovery from 5 kinds of processed foods spiked with 10 mg/kg of stevioside （SS）, 10 mg/kg of rebaudioside A （RS）, or 100 mg/kg of α-glu­cosyltransferase-treated stevia （Gts） product was excellent, and no interfering peak was observed. Thirty-six commercial processed foods indicated as containing “stevia” were analyzed using this established method. Among them, 33 contained SS, 33 contained RS, and 11 contained Gts. Five products contained both stevia extract and Gts.

We recently reported polymorphism in the mitochondrial genes of Tribolium castaneum, a stored grain pest. Here, we show that T. castaneum samples from the main island of Japan can be easily differentiated from samples from other areas by using real-time PCR with minor groove binding (MGB) TaqMan probes containing a single nucleotide polymorphism (SNP) to amplify a 179-bp fragment. This assay was also applicable to samples stored at room temperature for 5 months after natural death, and samples whose DNA was artificially degraded by heat, pressure, or gamma-ray irradiation.

The official method described in Direction Notification Kanshoku No. 99 （May 8, 1981） for the determination of chlorophyll decomposition products including pheophorbide was verified and improved in order to overcome several problems. Firstly, extraction with a mortar required improvement because of the difficulty of maintaining equal power for a long time. Secondly, the saturated sodium sulfate reagent caused a red-shift of the absorption maximum wavelength from the measured wavelength given in the official method; consequently, the absorption was decreased and a new absorption peak was detected around 729 nm. As a result, chlorophyll decomposition products including pheophorbide were underestimated. Lastly, it was impossible to make up the volume of the diethyl ether layer accurately to 20 mL before measuring the absorption. These points were improved in the modified method, and a validation test was performed. The mean recovery was 82.7％ and the within-laboratory reproducibility was 5.8％.

We measured the concentrations of organophosphorus pesticide （chlorpyrifos-methyl, pirimiphos-methyl and fenitrothion） residues in domestic and imported commercial wheat products （flour, noodles, cookies） collected from 2008 to 2016. Chlorpyrifos-methyl and fenitrothion in domestic flour samples were detected in 16 out of 34 samples at levels of ＜0.001 to 0.016 ppm, and in 14 out of 34 samples at levels of ＜0.001 to 0.004 ppm. Chlorpyrifos-methyl was detected in 22 out of 38 domestic cookies at levels of ＜0.001 to 0.054 ppm （median: 0.001 ppm）. Relatively high concentrations of chlorpyrifos-methyl （0.005 to 0.054 ppm） were found in six domestic cookies containing wheat bran. Pirimiphos-methyl was detected in 32 out of 68 cookies from foreign countries at levels of ＜0.001 to 0.11 ppm. Pirimiphos-methyl was detected frequently in products imported from Europe.

We measured the residual amounts of chlorantraniliprole in various vegetables and fruits. Sample solutions were prepared according to our routine procedure based on the QuEChERS method and analyzed by LC-MS/MS. Performance characteristics were evaluated for 8 kinds of food samples by means of recovery tests of 5 replicates at the concentration of 10 ng/g. Recoveries and RSDs (％) ranged from 50.2 to 93.4％ and from 2.1 to 9.7％, respectively. Application of this method to survey 207 vegetables and 163 fruits gave detection rates of 8.2 and 1.2％, respectively. In vegetables, detection rates were high in okra (4 out of 10 samples), paprika (4 out of 23 samples) and tomato (2 out of 6 samples), and leaf vegetables such as lettuce, mizuna, spinach and wrinkled greens also contained high concentrations of chlorantraniliprole. The highest residual concentration was 571 ng/g in mizuna. The samples containing chlorantraniliprole seemed to be mainly from Asian countries, including samples of domestic Japanese origin. However, none of them contained more than the MRL, which suggests that the use of chlorantraniliprole has been properly controlled.

Between fiscal years 2014 and 2016, we surveyed the concentration of radioactive cesium in commercial foods produced in areas where there is a risk of radiation contamination due to the Fukushima Daiichi nuclear disaster. The number of samples with a concentration of radioactive cesium that exceeded the regulatory limit （100 Bq/kg for general foods） was 9 out of 1,516 （0.6％） in fiscal 2014, 12 out of 900 （1.3％） in fiscal 2015, and 10 out of 654 （1.5％） in fiscal 2016. Even though some samples were expected to be contaminated with radioactive cesium, because wild mushrooms and edible wild plants were intentionally included in this survey, the percentage of samples that exceeded the regulatory limit was only around 1％. The surveillance results confirmed that the pre-shipment food monitoring conducted by local governments was properly and efficiently performed, although continuous monitoring of the concentration of radioactive cesium in cultivated and wild mushrooms, edible wild plants, and wild animal meats is still required.

New analytical methods for the determination of free asparagine （Asn）, which is a precursor of acrylamide, in grains were developed using LC-MS and LC-MS/MS. Asn was extracted from a sample with 5％ （w/v） aqueous trichloroacetic acid solution, appropriately diluted with 0.1％ （v/v） formic acid solution, and then analyzed by LC-MS or LC-MS/MS. HPLC separation was performed by isocratic elution on a Penta Fluoro Phenyl （PFP） column using 0.1％ （v/v） formic acid and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.005–0.1 μg/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 95.4 to 100.9％, repeatability （RSD） ranged from 0.9 to 6.0％, and within-laboratory reproducibility （RSDwr） ranged from 2.8 to 7.1％. Limits of quantitation （LOQs） were 7 mg/kg for potato starch, and 5 mg/kg for non-glutinous rice flour. In addition, an inter-laboratory study was performed in 10 laboratories using 5 kinds of grains （non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour）, which naturally contained free asparagine. The HORRAT_R values ranged from 0.4 to 1.0. These results are within the range of the procedural manual of the Codex Alimentarius Commission, confirming the effectiveness of the developed procedures.