Food Hygiene and Safety Science最新文献

In this study, a multi-residue method for pesticide residues in green tea leaves was developed using LC-MS/MS and the validity of the developed method was evaluated in accordance with Japanese guidelines. Based on the previously reported method, the amount of acetonitrile used for extraction, amount of hexane-washed distilled water added to the sample, and solid-phase column used for purification were investigated. In the developed method, the pesticides were extracted with 25 mL of acetonitrile after adding 10 mL of the hexane-washed distilled water to the sample and salted out. By cleaning the acetonitrile layer using Inert Sep^® PLS-3 (200 mg/20 mL) and Supelclean^TMENVI-Carb^TMII/PSA (300 mg, 600 mg/6 mL), the effect of the matrix on the green tea leaves was reduced. This method was validated by performing recovery tests at two concentrations (0.01 and 0.1 mg/kg) of 92 pesticides. Of the 92 pesticides, 84 met the criteria. The limit of quantification was 0.01 mg/kg, which is the uniform limit specified by the Food Sanitation Law of Japan. This study presents that the developed method is useful for the analysis of pesticide residues in green tea leaves.

Saxitoxin (STX) and its analogues produced by toxic dinoflagellates in marine environments are known as specific voltage-gated sodium channel blockers and can be detected by the mouse bioassay (MBA) that has been used as the official testing method for paralytic shellfish toxin monitoring systems worldwide. Considering animal welfare issues and improved performance of analytical instruments, it would be better to replace MBA with non-animal testing methods such as LC-MS/MS which have been recently reported for the detection of STXs in shellfish. However, STX itself is regulated by the Act on the Prohibition of Chemical Weapons, so the domestic use of the reference material is required with permission from the relevant government department. Therein, nontoxic enantiomeric STX (ent-STX) was developed as an alternative reference material for STX. In this study, the LC-MS/MS method using ent-STX-fortified scallops homogenate was validated in accordance with a previous report and CODEX-STAN 292-2008. The spiked concentrations of ent-STX were set to the regulatory limits of CODEX (0.8 mg of STX-2HCl equivalents/kg) and approximately half of the limits. The calibration standard solutions were prepared by dilution with solvent and non-toxic scallop extract, respectively, and were used to quantify the toxins by absolute calibration method. As a result of the validation, the results with ent-STX were found falling within all the guideline criteria (the trueness, repeatability, within laboratory re-producibility, and minimum applicable range). Moreover, ent-STX was used to confirm and quantify STX in mussels, scallops and noble scallops. The ent-STX was confirmed to be utilized as reference material. However, it can be sometimes detected an unidentified STX analogue in Japanese bivalve molluscs with retention time close to STX under the qualitative and quantitative selected reaction monitoring (SRM) conditions of STX which are often used in the previous reports. To avoid the assignment of the unidentified STX analogue to STX, appropriate SRM conditions of m/z 300.1>282.0 need to be selected.

In this study, we developed a simultaneous extraction method for 19 food additives, including sweeteners, preservatives, and antioxidants, to enhance testing efficiency across a wide range of processed foods. Samples underwent 2 or 4 extractions with acetonitrile containing 0.05 w/v% ascorbic acid palmitate, facilitated by the addition of water, phosphoric acid, magnesium sulfate, and sodium chloride. The extracts were then diluted and analyzed using instruments tailored to each specific compound. Recovery tests (n=5 or n=3) on 22 samples, encompassing high-protein, oily, and powdered foods, demonstrated satisfactory recovery rates between 76.6% and 111.6% (RSD: 0.1-6.6%). To validate the method, two concentrations-corresponding to the lower limit of quantification and the maximum permissible level-were added to two or three different samples per additives. This validation was conducted by a single analyst over two parallel runs across five days. The results indicated that the lower limit of quantification achieved trueness of 81.7-102.4%, repeatability of 0.3-6.3%, and within-laboratory reproducibility of 1.0-9.7%. Similarly, for the maximum level of use, trueness ranged from 80.6 to 105.5%, repeatability from 0.4 to 2.8%, and within-laboratory reproducibility from 0.6 to 4.3%, all meeting the target criteria. The developed method proves to be a valuable analytical tool, significantly enhancing the efficiency of food additive analysis.

Food allergen analysis using LC-MS/MS has attracted attention in recent years because it can analyze multiple allergens at the same time and has high detection sensitivity and specificity. We have been actively researching for developing this testing method using LC-MS/MS. In this study, we developed the simultaneous detection method for allergens using LC-MS/MS and conducted an interlaboratory validation study in three laboratories to evaluate the effectiveness of the developed method. The study was conducted using two types of model processed foods: rice porridge and pancake. A total of nine allergens were targeted (wheat, egg, milk, peanut, buckwheat, crustaceans (shrimp and crab), walnut, and soybean). The results of the interlaboratory validation study showed that the qualitative and quantitative tests demonstrated good accuracy and, with the exception of a few allergens, exhibited a high level of agreement when compared with other laboratories. This indicates that the developed method is practical as a screening method for simultaneous detection of food allergens and can be applied to foods containing allergens.

The detection sensitivity of the protein wiping method based on BCA assay was evaluated for specified allergenic food ingredients. The detection sensitivity was measured when BSA samples and eight specified allergenic food ingredients (shrimp powder, crab powder, walnut paste, wheat flour, buckwheat flour, liquid egg, milk, and peanut powder) were applied to 25 cm² stainless steel surfaces, dried, and subsequently wiped off with a swab. The visually detectable limit was determined to be 2-2.25 μg using a BSA solution as the standard, with an absorbance of approximately 0.3 at 562 nm. Test areas with low (2.5 μg/25 cm²), medium (5.0 μg/25 cm²), and high (7.5 μg/25 cm²) contamination levels were prepared, and recovery tests were performed using the protein wiping method. The measurement error was within ±0.03. Moreover, the recovery rate from swabs was observed as 78.2-94.4%. Recovery tests for eight specified allergenic food ingredients showed the ability to detect the ingredients when >10 μg of material was applied to the test surface. This study suggested that the protein wiping method is useful for cleanliness control to prevent cross-contact of allergens in the food manufacturing environment.

Peracetic acid formulation has received much attention in recent years as a surface disinfectant for beef. There are many reports on the bactericidal effect of peracetic acid formulation on beef surfaces. However, the application method of peracetic acid formulation aiming at the complete removal of Shiga toxin-producing Escherichia coli (STEC) from the surface of sub-primal cuts has not been evaluated. The objective of this study was to determine the condition under which peracetic acid formulation can be used to completely remove STEC from the surface of sub-primal cuts of beef.The effect of peracetic acid formulation was evaluated by immersing pieces of beef on whose surfaces E. coli O157:H7 were inoculated. To investigate the impact of peracetic acid concentration on bactericidal efficacy, small pieces (5 cm×5 cm×5 cm) of meat from five parts were immersed in peracetic acid at concentrations of 900 ppm and 1800 ppm for 30 min. The bacterial counts were decreased by 2.6-4.0 log CFU/cm² at 900 ppm, indicating a varying bactericidal effect depending on parts of beef. Conversely, at 1800 ppm, declines of 3.9-4.1 log CFU/cm² were observed, reaching the detection limit. To confirm the efficacy of peracetic acid formulation on the surface of sub-primal cuts, larger pieces (5 cm×20 cm×20 cm) of beef from nine parts were immersed in 1800 ppm peracetic acid for 30 min. As was the case with small pieces of beef, bacterial counts were decreased by 3.5-3.8 log CFU/cm² and reached the detection limit. Given the actual number of total viable bacteria on the surface of sub-primal cuts, the reduction in bacterial counts observed in this study is a condition that allows for complete removal of STEC from the surface of sub-primal cuts.Consequently, it can be concluded that the immersion in peracetic acid with a concentration of 1800 ppm for 30 min is the appropriate treatment to decontaminate STEC totally from the surface of sub-primal cuts of beef.

For amino acids used as food additives, Japan's Specifications and Standards for Food Additives stipulate the ninhydrin test as an identification test. The ninhydrin test is a simple method that involves the visual determination of purple color from the formation of Ruhemann's purple (RP) and does not require special equipment, facilitating its widespread use in society. However, because of this background, objective and molecular selective observation methods for monitoring RP itself as an analyte have not been fully investigated. Therefore, in this study, a UHPLC/MS/MS method was developed to specifically monitor RP and support visual judgment. This method identified RP-derived fragment ions at m/z 170 (ESI (-)) and 133 (ESI (+)), which can be monitored in the multiple reaction monitoring mode and were shown to correlate with the intensity of the purple color. In addition, computational chemistry was applied to scientifically estimate the molecular structures of the fragment ions. In this study, we established a useful analytical method that complements the objectivity of the ninhydrin test. This method is also expected to be utilized for further optimization of test reaction conditions.

Assuming food poisoning caused by toxic plants, an LC-TOF-MS-based method for the rapid and simultaneous analysis of 16 plant toxins was established. After adding water-methanol (1 : 9) and n-hexane, the samples were homogenized and extracted, and then subjected to centrifugal separation. Without any purification procedures, LC-TOF-MS measurements were performed, and qualitative and quantitative analyses using monoisotopic ion [M+H]+ (m/z) were conducted. The addition-recovery test using curry showed that qualitative analysis was possible under a setting with a retention time of ±0.2 minutes or less and mass accuracy of 5 ppm or lower and that quantitative analysis was possible with a recovery rate of 68-142% and a repeatability of 1.4-10.1%. Furthermore, measurements of the amount of plant toxins in the boiled plants and broths of cooked toxic plants demonstrated the transfer of plant toxins to broths. These suggest that in the event of food poisoning, broths may be used as an analysis sample, even when plants are not available.

Ciguatera fish poisoning (CFP), known as a seafood-borne disease, is caused by consumption of fish contaminated with ciguatoxins in tropical and subtropical sea. The ciguatera fishes, Variola louti, Lutjanus monostigma and L. bohar have an absolute majority in the Ryukyu Archipelago, southwestern Japan. We developed the cluster analysis of phylogenetic tree by using mitochondrial (mt) DNA 16S rRNA sequences of V. louti, L. monostigma and L. bohar and differentiate them from morphologically similar species (L. fulviflamma, L. russellii, L. argentimaculatus, Plectropomus leopardus and V. albimarginata) in our previous study. The fish were acquired from the coastal waters of the Ryukyu Archipelago, and a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) marker of the mtDNA 16S rRNA region was used, employing the restriction enzymes BmgT120 I, Dde I, and SnaB I, to identify the fish species responsible for CFP. These results showed that a PCR-RFLP marker can be obtained more easily than a nucleotide sequence.

An outbreak of Salmonella Stanley in the United States associated with dried wood ear mushrooms imported from China prompted us to conduct serotyping of Salmonella isolated from dried wood ear mushrooms in voluntary testing, and quantitative test for Salmonella along with enumeration of hygienic indicator bacteria in positive samples in order to evaluate the risk of Salmonella outbreak from dried wood ear mushrooms. The major serovars of Salmonella isolates obtained from 20 samples were as follows: O3,10 group-London (n=3) and Weltevreden (n=5) etc, totaling 9 strains; O4 serogroup-Saintpaul (n=2), Stanley (n=1), Typhimurium (including monophasic variant; n=3), totaling 6 strains. O7 serogroup (Potsdam) and O8 serogroup (Newport) were one strain each. Qualitative and quantitative tests for Salmonella were conducted on 10 samples with remaining amounts. As a result, one sample was 220 MPN/g, six samples were<0.6 MPN/g, and three samples were negative for Salmonella per 25 g. The mean aerobic bacterial counts and coliforms in these samples were 7.8 and 6.1 log₁₀ CFU/g, respectively. Furthermore, qualitative test for Salmonella and enumeration of hygienic indicator bacteria were conducted on dried wood ear mushroom products (33 domestic and 30 imported products) retailed in Japan. No samples showed positive for Salmonella per 25 g, and the mean aerobic bacterial counts and coliforms were approximately 2 log₁₀ CFU/g lower than those in the 10 samples where Salmonella was isolated during voluntary testing. While no Salmonella was detected in domestically retailed wood ear mushrooms products, the serovars associated with foodborne diseases were isolated from voluntary testing samples. It indicates that potential for consumption of Salmonella contaminated wood ear mushrooms, which is at risk of causing food poisoning.