Food Hygiene and Safety Science最新文献

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.

In the Japanese official detection method for unauthorized genetically modified (GM) papayas, one of two types of real-time PCR reagents with DNA polymerase (TaqMan Gene Master Mix [TaqMan Gene] or FastGene QPCR Probe Mastermix w/ROX [FastGene]) is primarily used for measurement. In 2022, we conducted a laboratory performance study on the unauthorized GM papaya line PRSV-YK, and the results revealed that high threshold cycle (Cq) values for the PRSV-YK detection test were obtained using TaqMan Gene with the 7500 Fast & 7500 Real-Time PCR System (ABI7500) and QuantStudio 12K Flex (QS12K), indicating the possibility of false negatives. The possibility of similar problems with all unauthorized GM papaya lines detection tests needs to be evaluated. In this study, we performed detection tests on unauthorized GM papaya lines (PRSV-YK, PRSV-SC, and PRSV-HN), the cauliflower mosaic virus 35S promotor (CaM), and a papaya positive control (Chy), and examined how the limits of detection (LOD) for each test are affected by two types of DNA polymerases (TaqMan Gene and FastGene) and three types of real-time PCR instruments (ABI7500, QS12K, and LightCycler 480 Instrument II [LC480]). In the PRSV-YK and PRSV-SC detection tests using ABI7500 and QS12K, measurement with TaqMan Gene showed a higher LOD than FastGene. In this case, an exponential amplification curve was confirmed on the amplification plot; however, the amplification curve did not cross the ΔRn threshold line and the correct Cq value was not obtained with a threshold line=0.2. The other tests (PRSV-HN, CaM, and Chy with ABI7500 and QS12K, and all detection tests with LC480) showed no important differences in the LOD for each test using either DNA polymerase. Therefore, when performing PRSV-YK and PRSV-SC detection tests with the ABI7500 or QS12K, FastGene should be used to avoid false negatives for foods containing GM papaya lines PRSV-YK and PRSV-SC at low mixing levels.

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.

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.

From October 2020 to February 2021, a total of 95 retail chicken meat products from 39 retail meat shops in Tokyo Metropolis and Kanagawa Prefecture, Japan, were collected and examined for the prevalence of Salmonella to assess public health implications. If a sample tested positive for Salmonella, a quantitative analysis was performed using the three-tube most probable number (MPN) method. Of 95 retail chicken meat products, Salmonella was isolated from 30 samples (31.6%). The levels of Salmonella contamination ranged from <0.3 to 4.3 MPN/g. The most frequent level was <0.3 MPN/g (63.3%). Of the 33 Salmonella strains isolated, four serotypes were identified: S. Schwarzengrund (60.6%), S. Infantis (24.2%), S. Agona (12.1%), and S. Manhattan (3.0%). Multilocus sequence typing (MLST) analysis classified most S. Schwarzengrund isolates into sequence type (ST) 241, the same ST found in chicken meat in Japan, except for one isolate. Of the 33 Salmonella isolates, 29 (87.9%) were antibiotic resistant. Twenty-six isolates (78.8%) showed multidrug resistance to two or more antibiotics. Therefore, these results indicate that retail chicken meat products in Japan are an important source of Salmonella infection in humans and that Salmonella contamination in retail chicken products seems to originate from chicken meat.