Bisphenol A, a monomer of polycarbonate plastics, disturbed the conversion pathway of the amino acid tryptophan to the vitamin nicotinamide. The conversion ratio of tryptophan to nicotinamide was reduced to 1/15 by feeding a diet containing 1% bisphenol A. A putative disturbing reaction is kynurenine→3-hydroxykynurenine, which is catalyzed by kynurenine monohydroxylase. This is an FAD-enzyme and requires NADPH as a coenzyme. Styrene monomer (1% addition to a normal diet) did not affect the food intake or the body weight, but slightly reduced the conversion ratio of tryptophan-nicotinamide.

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A 52-week study of oral-repeated-dose toxicity for the extraction powder of Gymnema sylvestre (GS), Indian-native genus, Metaplexis japonica, was conducted in both genders of Wistar rats. The rats were administered a graded dose of GS at 0.01, 0.10 and 1.00% of basal powder diet, along with a group fed solely with the basal powder diet without GS, for 52 weeks. General conditions were recorded daily. Body weights and food consumptions were recorded weekly up to 12 weeks, and thereafter at longer intervals. At 26 weeks, for an intermediate examination, and 52 weeks, for the final examination, animals were subjected to hematology, serum chemistry, and pathological examination.
None of the animals died in the period up to 52 weeks. No exposure-related changes in body-weight, in the food consumption, in the hematological examinations, or in the serum biochemical examinations were recognized. No histopathological alterations were seen. Thus, it was concluded that there was no toxic effect in rats treated with GS at up to 1.00% in the diet for 52 weeks. The no-observable-effect level from this study is 1.00% GS, i.e., 504 mg/kg/day for male and 563 mg/kg/day for female as mean daily intake, for 52 weeks.

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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 β-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-β-D-glucuronide (X-Gluc) in a 96-well microtiter plate for 10-15 hours at 37°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.

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To simplify the labor-intensive conventional routine testing of samples to detect Leuconostoc at a meat processing plant, we developed polymerase chain reaction (PCR) primers specific for Leuconostoc from 16S rRNA gene sequences. These primers did not detect other common lactic acid bacteria such as Lactobacillus plantarum, Lact. sake, Lact. fermentum, Lact. acidophilus and Weissella viridescens. PCR with this primer detected all Leuconostoc species tested (Leu. mesenteroides subsp. mesenteroides, Leu. pseudomesenteroides, Leu. carnosum, Leu. lactic, Leu. citreum, Leu. amelibiosum, Leu. gelidum), except for Leu. fallax, and no other lactic acid bacteria on agarose gel electrophoresis. The method could identify areas contaminated with Leuconostoc in a large-scale industrial meat processing plant. Of 69 samples analyzed, 34 were positive for Leuconostoc according to the conventional culture method (isolation of LAB producing dextran) and PCR, whereas 29 were negative according to both. Six samples were culture-negative but positive by PCR. No false negative results were generated by PCR. The method is rapid and simple, is useful for routinely monitoring areas contaminated with Leuconostoc in meat processing plants, and could help to prevent the spoilage of meat products.

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The effect of coexisting metals in a sample on the determination of lead and cadmium in plastics used for food contact materials was investigated. In the official method specified in the Japanese Food Sanitation Law, contents of lead and cadmium are determined by a dry incineration method using sulfuric acid. It was assumed that sometimes, coexisting metals in a sample may form insoluble sulfate and that lead sulfate might be adsorbed into the insoluble sulfate. Therefore, hydrochloric acid was added to the ash, to turn formed insoluble sulfate into soluble compounds (HCl addition method). We found that recoveries of cadmium were not affected in the presence of other metals except when calcium exceeded 20 mg/g in both methods. Recoveries of lead decreased in the presence of barium exceeding 0.1 mg/g or calcium exceeding 10 mg/g in the official method. However, improvement of recoveries was achieved with the HCl addition method and by reducing the sample amount to one-tenth (0.1 g) of that specified in the official method.

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The growth responses of Vibrio parahamolyticus to pH, NaCl concentration and temperature changes were studied using serotype O3 : K6 and other strains. Growth curves were obtained for 27 different sets of conditions, comprised of three levels of NaCl concentration, pH and temperature. The temperature, pH and NaCl concentrations most favorable for growth were in the order of 25°C, 20°C and 15°C, pH 8, 7 and 5.8, and 1%, 3% and 7%, respectively. The bacteria grew most rapidly at 25°C, at a pH of 7 or 8 in the presence of 1% or 3% NaCl, with the population (initial, ca. 2.5 log CFU/mL) reaching a level log 7 CFU/mL at 12 h. A growth predictive model using the Gompertz equation was generated from the experimental data for any combination of NaCl concentration, pH and temperature within the range used in this study.

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A rapid analytical method for residues of the herbicide, glyphosate [N-(phosphonomethyl)-glycine], glufosinate [DL-homoalanine-4-yl(methyl)phosphinic acid] and glufosinate metabolite (MPPA: 3-methylphosphinicopropionic acid) in vegetables and fruits was developed by improving the bulletin method of glufosinate. 50 mL of solution extracted with water (corresponding to 2 g of the sample) was loaded on a column packed with 5 mL of anion exchange resin and then the trapped glyphosate, glufosinate and MPPA were eluted with 60 mL of 50% acetic acid. After derivatization with trimethyl orthoacetate, the derivatives were purified and separated on a Florisil cartridge column. The determination of the derivatives was performed with GC-FPD. The detection limits for glyphosate, glufosinate and MPPA were 0.01 μg/g, 0.01 μg/g and 0.005 μg/g, respectively. The recoveries from fortified samples were 83.5-89.8% for glyphosate, 77.9-92.2% for glufosinate and 75.0-87.2% for MPPA.

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Some model studies were performed using various agricultural Products, to clarify the relation between cooking conditions and production of acrylamide (AA). Disc chips made from dried mashed potato, corn meal, wheat flour, rice flour (jyohshin-ko) and glutinous rice flour (shiratama-ko), and dried sesame (arai-goma) and dried almond were baked at 120-200°C for 5-20 min, and the samples were analyzed for the levels of AA. When the samples were baked for 10 min, the highest production of AA was observed at 180-200°C. When the samples were baked at 180°C, AA levels in agricultural products except sesame were highest after baking for 10 min. Vegetables and fruit were baked at 220°C for 5 min with a oven, high AA concentrations were found in baked potato, asparagus, pumpkin, eggplant and green gram sprouts. Concentrations of AA in potato, asparagus and green gram sprouts baked after being precooked by microwave irradiation were higher than those in the products baked without being precooked. On the other hand, the precooking by boiling reduced the production of AA by baking to 1/10-1/4. Acrylamide was not found in microwaved or boiled vegetables. High free asparagine concentrations in crops tended to result in high concentrations of AA being produced by heating the agricultural products.

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Natural sex hormones, estradiol-17β (EST), progesterone (PRO) and testosterone (TES), in sixty domestic bovine muscles and forty bovine muscles imported from USA and Australia were determined by radioimmunoassay. The EST, PRO and TES levels (mean±standard deviation) in domestic samples (n=60) was 1.15±1.87 ppt, 3.19±5.80 ppb and 30.9±122.1 ppt on a whole basis, respectively. The hormone levels in muscles was presumed to reflect sex, estrous cycle, and so on. The hormone levels in imported bovine muscles (n=40) were 3.33±2.83 ppt (EST), 0.52±0.50 ppb (PRO) and 8.8±13.0 ppt (TES), respectively.

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We evaluated simultaneous analytical methods for organophosphorus pesticides in cruciferous vegetables by gas chromatography (GC). Firstly, 36 pesticides were selected on the basis of monitoring data (April 1996-March 2003) in Aichi Prefecture. A sample was extracted with acetonitrile and the acetonitrile layer was separated by salting-out. The extract was cleaned up with gel permeation chromatography (GPC), and then with a tandem silica-gel/PSA mini-column. The test solution was subjected to dual-column GC equipped with a pulsed FPD (P mode, Rtx-OPPesticides column) and a FTD (Rtx-OPPesticides 2 column). Organophosphorus pesticides in such sulfur-rich matrices as cabbage and radish were determined without any serious interfering peaks on the pulsed FPD chromatograms after diluting the extracts 10- to 20-fold (0.25-0.5 mg/L of sample). The method was applied to cruciferous vegetables to demonstrate its usefulness in routine analysis.

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