[AFM1 Content Survey in Dairy Products for Infants].

Infant formula in liquid for childcare can be stored at room temperature for a certain period of time, reducing the burden of childcare and preparing for disasters. Against this background, domestic manufacturing and sales began in March 2019. AFM1 is a metabolite of aflatoxin B1 (AFB1), a carcinogenic mycotoxin, and is contained in the milk of livestock fed a diet contaminated with AFB1. At present, standard values have not been set for infant formula in liquid as well as prepared infant formula in liquid, and infants consume a large amount of dairy products per body weight, so care must be taken in the intake.In this study, we investigated the actual condition of AFM1 content in dairy products with high intake of infants. As a result of the investigation, the AFM1 of the detected dairy products was 0.001 to 0.005 µg/kg, which was extremely small compared to the AFM1 in the dairy products reported so far. Since infant nutrition depends on dairy products, it is undeniable that they may consume more than adults, so continuous research is needed.

[Nomenclature and Identification Method of Non-Permitted Dyes of Patent Blue Group].

Violation of the Food Sanitation Act regarding detection of Patent Blue V, which is one of the non-permitted dyes for food in Japan, in imported food occurs every year. With respect to the identification of dyes of Patent Blue group, in some cases, each dye has several different names, and in other cases, different dyes have the same name. Thus, there is a risk that the detected dye is misidentified with other dyes of Patent Blue group. In this study, nine commercial available dyes of Patent Blue group, including a reagent with unclear product information, were analyzed by TLC, HPLC and LC-MS/MS. The result showed that with all three methods, the dyes could be clearly identified into one of four types of blue dyes, i.e. Patent Blue V, Azure Blue VX, Isosulfan Blue and Alphazurine A. Unification of nomenclature would reduce the risk of misidentification of dyes of Patent Blue group.

Development of monoclonal antibody-based ELISA for the quantification of orange allergen Cit s 2 in fresh and processed oranges.

The aim of this study was to develop a monoclonal antibody (mAb)-based enzyme-linked immunosorbent assay (ELISA) for the quantification of a major allergen (Cit s 2) in fresh and processed oranges. Purified recombinant Cit s 2 (rCit s 2)-small ubiquitin-like modifier (SUMO) was used for the production of mAbs. In the optimized ELISA, the recovery of rCit s 2 from Navel oranges or orange juice was 107-132%, and the intra- and inter-assay coefficients of variation were 3.1-8.8% and 4.4-11%, respectively. The Cit s 2 content in fresh oranges was determined to be 1,800±430ng/g, while this content was much lower in the processed foods. The developed ELISA demonstrated high reproducibility, sensitivity, and accuracy, and this assay may help individuals with orange allergy by determining Cit s 2 quantities in food products and controlling their Cit s 2 intake.

A histochemical method using a substrate of beta-glucuronidase for detection of genetically modified papaya.

A histochemical assay for detecting genetically modified (GM) papaya (derived from Line 55-1) is described. GM papaya, currently undergoing a safety assessment in Japan, was developed using a construct that included a beta-glucuronidase (GUS) reporter gene linked to a virus coat protein (CP) gene. Histochemical assay was used to visualize the blue GUS reaction product from transgenic seed embryos. Twelve embryos per fruit were extracted from the papaya seeds using a surgical knife. The embryos were incubated with the substrate 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide (X-Gluc) in a 96-well microtiter plate for 10-15 hours at 37 degrees C. Seventy-five percent of GM papaya embryos should turn blue theoretically. The histochemical assay results were completely consistent with those from a qualitative polymerase chain reaction (PCR) method developed by this laboratory. Furthermore, the method was validated in a five-laboratory study. The method for detection of GM papaya is rapid and simple, and does not require use of specialized equipment.

Discrimination of mushrooms causing food-poisoning incidents by using DNA sequence analysis.

In this study, the identification of mushrooms by using DNA analysis was investigated. Our analysis of internal transcribed spacer (ITS) regions revealed that a DNA-based method could be applicable for samples that are difficult to distinguish in terms of the morphological characteristics. PCR amplification using templates extracted from cooked samples gave sufficient fragments to analyze the sequence. However, treatment with simulated gastric fluid (SGF) for more than 30 min affected the analysis of the ITS region. Application to samples of vomit is also discussed.

DNA-based identification of fish species implicated in Puffer fish poisoning.

A method for identification of fish species using three different mitochondrial DNA regions, 16S rRNA, cytochrome b and cytochrome c gene fragments, was investigated. The combined use of all three regions enabled reliable species identification in not only raw fish, but also dried, seasoned and boiled fish, products. Furthermore, the method was applicable even to vomitus from a patient involved in a puffer fish poisoning incident. However, further improvement is necessary to discriminate between closely related species such as Takifugu rubripes and T. chinensis, because they showed close similarity in the nucleotide sequences in the three gene fragments analyzed in this study.