Migration test of food utensils, containers, and packaging is an important test method for confirming the safety and their compliance to the standards. However, there is little report on inter-laboratory study which was performed to evaluate the entire migration test, including migration operations and quantification. An interlaboratory study was performed participating 22 laboratories using 8 types of model synthetic resin samples containing 10 substances with a wide range of Log Pow values to evaluate the accuracy of the entire migration test. As a result, most of HorRat (r) values met the target criteria (0.3<HorRat (r) ≦1.3), but many of HorRat (R) values exceed the target criteria (0.5<HorRat (R) ≦2.0). The results showed good accuracy within the laboratory. However, we found that there was a problem in accuracy between laboratories. The main reason was considered to be the difference in the preparation of migration solution between the laboratories, such as temperature and time control during the migration operation.
To evaluate the effects of handling “not detectable” residues (ND: <0.01 mg/kg) in the pulp and detectable residues in the pits on the calculation of pesticide residue in the whole fruit, residue levels in the pulp, peel, and pits of loquat fruits were separately analyzed. Following conventional Japanese agricultural practices, 16 pesticides were sprayed at the maximum application rates in three test fields. All target pesticides were detected at quantifiable levels in the peel (n=144). In contrast, the percentages of detected pesticides in the pulp and pits were 42% (n=61) and 36% (n=52), respectively. Most pesticide residues were present in the peel. For comparison, the pesticide residue levels in the whole fruits were determined based on three indices: the highest estimate (H), calculated using the measured residue levels in the pits and by replacing the ND residues in the pulp as the limit of quantification (LOQ) values; conventional estimate (C), calculated by neglecting all residues in the pits (0 mg/kg) and replacing the ND residues in the pulp as LOQ values; and the lowest estimate (L), calculated by neglecting all residues in the pits and the ND residues in the pulp (0 mg/kg). The L/C and H/C ratios ranged from 74% (L/C) to 106% (H/C). In seven of eighty-three cases with less than 90% difference, residue levels in the whole loquat fruits were low (≤0.06 mg/kg), with the actual range being equal to or below the minimum unit of 0.01. In comparison of three field datasets, the range of residue levels was estimated to be 2.77 mg/kg. Based on the results of separate analysis, handling of ND residues in the pulp and detectable residues in the pits did not significantly affect the calculated pesticide residue levels in the whole loquat fruits.
After washing the cooking utensils used to prepare liquid batter, flour may remain in the scrubbing sponge. Secondary contamination of cooking devices with wheat allergens is a concern if such scrubbing sponges are used to clean other equipment. Therefore, in this study, bowl washing with detergent, using a scrubbing sponge was evaluated as a cleaning method following liquid batter cooking. Multiple trials revealed that wheat allergens were transferred from a bowl coated with 10 g of liquid batter to an unused bowl via sponge scrubbing with a positive rate of approximately 80%. Residual batter was observed in the scrubbing sponge after cleaning and rinsing procedures, with a residual rate of about 20%. Detailed observation of the residue revealed that proteins such as gluten were attached to the cell skeleton, and between the skeletons of the sponge, and starch granules were attached to the proteins. Even with sponge rinsing conditions added to the protocol, complete removal of wheat allergen was difficult. These studies indicate that particular scrubbing sponges for cleaning the residual wheat on cooking utensils should be dedicated exclusively in cooking facilities that prepare allergy-friendly-foods to avoid risk of allergen contamination.
An isolation method for Acromelic acids A, B and Clitidine, which are venomous constituents of Paralepistopsis acromelalga was developed. Highly purified products were obtained from the mushroom extract using silica gel, ODS, ion-exchange column chromatography and preparative TLC. Using those results, we optimized the LC-MS/MS conditions. Finally we developed a method for simultaneous analysis. In recovery tests, the average recovery was 80.8–112.4%, repeatability was 1.4–3.8RSD%. The limits of quantification of the respective compounds were estimated as 0.25 μg/g. Based on the results, this method can reveal causes of food poisoning by Paralepistopsis acromelalga.
The total mercury content in 112 fishery products, purchased from Osaka city during 2013–2018, was measured using a heating vaporization mercury analyzer. The average total mercury content in all tuna processed products was found out to be 0.115 μg/g (median=0.070 μg/g). Notably, albacore tuna exhibited the highest mercury content with an average concentration of 0.301 μg/g (median=0.296 μg/g). The total mercury concentration of the fishery products, except processed tuna and Kezuribushi (comprising shavings of dried and smoked mackerel, sardine, as well as horse mackerel), was generally low (<0.1 μg/g).
The provisional tolerable weekly intake (PTWI) for mercury as set by the Joint FAO/WHO Expert Committee on Food Additives is 4.0 μg/kg body weight/week. On an average, for Japanese diet, the total weekly mercury intake from fishery products for a person weighing 50 kg was estimated to be 0.13 μg/kg body weight/week, which was 3.3% of the PTWI. These values indicate that it was not a problem to consume fishery products normally. However, albacore tuna cans have a relatively high total mercury concentration; thus, pregnant women consuming them daily may exceed the tolerable weekly intake of methylmercury (2 μg/kg body weight/week) as set by the Food Safety Commission of Japan.
By using the LC-MS/MS method developed by us, we determined the residual amounts of acaricides in honey samples commercially available in Tokyo from April 2015 to March 2021. The results of analyzing 127 honey samples, amitraz was detected in 85 samples at the level of 1.1–34.1 μg/kg. Propargite was detected in 3 samples at 2.4–3.8 μg/kg. None of them was beyond the Japanese MRLs or uniform limits. In these survey for 6 years, amitraz was detected in high rate throughout the year. But, the present results imply that amitraz has been used properly in actual bee-keeping because of no violation of MRL and less fluctuation in the detected levels. On the other hand, propargite was detected at the levels over LOQ in domestic honey samples for the first time in 2020, which may suggest a new trend of acaricide use in apiculture in Japan.
We modified a method for determining methanol content in detergents used in kitchens. Furthermore, an inter-laboratory study was conducted in 10 laboratories to validate the modified method. In this study, two concentrations of samples were blindly coded. Each laboratory determined the methanol content in each sample according to a protocol. The determined values were statistically analyzed according to an international harmonized guideline. HorRat values were calculated based on the reproducibility relative standard deviation (RSDR) which was estimated from the interlaboratory study, and predicted RSDR calculated from the Horwitz/Thompson equation. The HorRat values of the two samples were 0.8 and 1.8, meeting the performance criteria of less than 2 set by the Codex Alimentarius for analytical method approval. These results confirm that this modified analytical method shows good performance as an analytical method for determining methanol content in kitchen detergents.