Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi)
Online ISSN : 1882-1006
Print ISSN : 0015-6426
ISSN-L : 0015-6426
Volume 46, Issue 6
Displaying 1-13 of 13 articles from this issue
Review
Originals
  • Manabu ASAKAWA, Haruyoshi TAKAYAMA, Rieko BEPPU, Keisuke MIYAZAWA
    2005 Volume 46 Issue 6 Pages 246-250
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    To assess levels of shellfish intoxication by the paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamarense, potential health risks to human shellfish consumers and the possible need for regulatory intervention, yearly variations of maximum cell density of this species were examined from 1993 to 2004 in Kure Bay and Kaita Bay, which are located within Hiroshima Bay, Hiroshima Prefecture, Japan. The seawater temperature was determined concomitantly. In Kure Bay, maximum concentrations of 1,400 and 1,300 cells/mL at 0 and 5 m depths were observed on 21 and 24 April 1997. In Kaita Bay, remarkably high concentrations above 1,000 cells/mL of A. tamarense were observed in two out of three years investigated. These facts suggest that the environment in both bays is favorable for the propagation of A. tamarense. The temperature range at which the natural population of A. tamarense blooms was generally from 12 to 16°C. Four strains (ATKR-94, -95, -97 and -01) from Kure Bay and one strain (ATKT-97) from Kaita Bay were established. The strain ATKR-94, cultured in modified SW-2 medium at 15°C for 15 days, showed a specific toxicity of 33.8×10-6 MU/cell. The toxins in all five strains exist almost exclusively as β-epimers (C2 (PX2 or GTX8), GTX3, dcGTX3 and GTX4), which accounted for 54.9 to 73.0 mol% of the total. The corresponding α-epimers (C1 (PX1 or epi-GTX8), GTX2, dcGTX2 and GTX1) accounted for 6.0 to 28.9 mol%. The toxin profiles of ATKR-97 and ATKT-97 were characterized by unusually high proportions of low-potency sulfocarbamoyl toxin, which comprised 62.4 and 68.2 mol%, respectively, of total toxins. In the toxic bivalves, the low-toxicity sulfocarbamoyl components, major components of A. tamarense, were present in amounts of only a few percent, suggesting that in vivo conversion of PSP occurs after ingestion.
    A comparison of the toxin profiles of the causative dinoflagellate and contaminated bivalves showed that PSP components exist in the bivalves in the form of α-epimers, presumably owing to accumulation or storage of the toxins.
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  • Manabu ASAKAWA, Rieko BEPPU, Makiko TSUBOTA, Katsutoshi ITO, Haruyoshi ...
    2005 Volume 46 Issue 6 Pages 251-255
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    As a part of our studies on paralytic shellfish poison (PSP) accumulation kinetics in bivalves, short-necked clam Tapes japonia was experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days, and the processes of PSP accumulation and bioconversion were investigated: the toxicity level was determined by mouse bioassay and toxin components were identified by high-performance liquid chromatography (HPLC). The strain of A. tamarense used in this study possessed a specific toxicity of 186.7±81 (mean±S.D., n=5)×10-6 MU/cell. Total toxin concentration of this strain was 140.4±61 (mean±S.D., n=5) fmol/cell. The toxicity level of short-necked clams increased almost in parallel with the abundance of A. tamarense, reaching 1.8, 3.2, 3.8, 3.5 and 4.6 MU/g meat for 2, 4, 6, 8 and 10 days of feeding, respectively. The accumulation rates of PSP toxins, which are the ratio of the total amount of toxins accumulated in the bivalves to the estimated intake in each feeding experiment, were 7.5, 8.1, 5.7, 4.2 and 4.4% for 2, 4, 6, 8 and 10 days, respectively. At the end of each exposure period, many undigested algal cells were found in pseudofeces under microscopic observation. There was a remarkable difference in the relative proportions of the predominant toxin components between A. tamarense and short-necked clams. The most notable difference was the change in the relative amounts of C2 (carbamoyl-N-sulfo-11 β-hydroxysaxitoxin sulfate), GTX1 and GTX4 during the first two days. In the toxic bivalves, the amount of C2, which is dominant in A. tamarense, decreased to below half a percent after being ingested. Subsequently, the amount of GTX1 in the shellfish meat reached 50.1 mol%, while that of GTX4 decreased to about half of that in A. tamarense. As for the configuration of 11-hydroxysulfate, PSP components in A. tamarense exist almost exclusively as β-epimers (GTX3, GTX4, C2 and C4), accounting for 72.8 mol% of the total. This contrasts with the case of the short-necked clams, where the β-epimers represented 25.8, 33.8, 30.8, 36.8 and 28.5 mol% of the total after 2, 4, 6, 8 and 10 days, respectively. PSP components seemed to be converted rapidly at an early stage of the feeding of A. tamarense.
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  • Nobuyasu SEIKE, Tetsuhisa MIWA, Takashi OTANI, Masako UEJI
    2005 Volume 46 Issue 6 Pages 256-262
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    A total of 148 samples of nine species of fruit were collected between 1999 and 2002 and analyzed for PCDDs, PCDFs (PCDD/Fs) and Coplanar PCBs. Sampling points within about 1 km of operational municipal waste incinerators that were considered sources of dioxins were defined as “near-source” areas, and all other sampling points were defined as “general” areas. The TEQ of apples collected from near-source areas was significantly higher than that from general areas (p<0.05). 3,3',4,4',5-PeCB (#126) was the main contributor to this difference in TEQs between apples collected from near-source areas and from general area. A principal component analysis performed to estimate the source of this congener revealed that not only the municipal waste incinerators, but also PCBs in the environment were associated with the high TEQ in apples collected from near-source areas. The daily intakes of PCDD/Fs and Coplanar PCBs from the fruits including skin were estimated to be 0.0082 pg-TEQ/kg b.w./day (ND=0) and 0.072 pg-TEQ/kg b.w./day (ND=1/2 LOQ). Though these values are likely to be overestimates, they are far lower than the tolerable daily intake set in Japan for PCDD/Fs and Coplanar PCBs (4 pg-TEQ/kg b.w./day). It is thought that fruit intake is not an important pathway of human exposure to PCDD/Fs and Coplanar PCBs.
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  • Keiko HIRATA, Yasuhiro SHIMAMURA, Keiko SUZUKI, Yuki SADAMASU, Koichi ...
    2005 Volume 46 Issue 6 Pages 263-269
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    We have developed an analytical method for components of α-glucosyltransferase-treated stevia, a food additive product. Suitable conditions to separate additional sugar from α-glucosyltransferase-treated stevia by using glucoamylase were found (55°C for 3 hr with 250 U of glucoamylase in 10 mL of reaction solution). By solid-phase extraction using a C18 cartridge column, polysaccharides were excluded from the sample, and the glycosides and sugar obtained after hydrolysis with glucoamylase were separated on another C18 cartridge column. The glycosides and sugar contents were determined by HPLC. By this method, additional sugar was detected in all of three product samples tested and the sugar was glucose. The contents of glucose and total glycosides (minus unreacted glycoside) were 25-42% and 35.7-52.5%, respectively. In α-glucosyltransferase-treated stevia, the sum of total glycosides and glucose amounted to 77.5-80.4% of the total and their recoveries from samples from which polysaccharide had been excluded by C18 cartridge column processing were over 85%. The contents of α-glucosyl-transferase-treated stevia obtained by multiplying the sugar content by the coefficient (0.9) for hydrolysis and converting on dry weight basis were all over 80.0% and met the standard set by the Japan Food Additives Association.
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  • Kikuko KASAMA, Takahiro WATANABE, Tatsuya SUZUKI, Hiroyuki KIKUCHI, Sh ...
    2005 Volume 46 Issue 6 Pages 270-276
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    To investigate important factors affecting the analytical results, a laboratory-performance study was attempted for the Japanese official methods to detect genetically modified (GM) soybeans (40-3-2). Test samples containing 0, 1 and 5% GM soya powder in non-GM soya powder was prepared. A set of 3 test samples was sent to the participating laboratories along with the protocol. The data were collected from all laboratories and statistically analyzed. In the real-time PCR detection method, the average values of the GM 1% and 5% samples were both much lower than the spiked value because the laboratories using a silica-membrane DNA extraction method underestimated the GM value. On the other hand, the laboratories using other extraction methods, such as the CTAB method obtained values close to the spiked value. These results suggest that use of the silica-membrane DNA extraction method may result in underestimation of the GM content in the real-time PCR method. In the ELISA method, the average value of 5% spiked samples appears to be slightly higher than the fortified value. But, overall, it was considered that reported values were close to the spiked level.
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Notes
  • Tsuyoshi IMAZAWA, Tomonari IIDA, Nobuhiro MATSUNO, Fumiaki KATO, Takes ...
    2005 Volume 46 Issue 6 Pages 277-281
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    An analytical method was developed for the determination of phenmedipham (PM) in agricultural products using reversed-phase high-performance liquid chromatography with UV detection.
    A sample was extracted with acetonitrile, and the acetonitrile layer was separated by salting-out. The acetonitrile phase was isolated and evaporated. The extract was dissolved in diethyl ether-hexane (1 : 1), and then cleaned up on a Florisil column. The column was washed with diethyl ether-hexane (1 : 1), and PM was eluted with acetone-hexane (3 : 7), and the eluate was evaporated.
    The residue was dissolved in acetone-hexane (2 : 8), and the sample solution was cleaned up on SAX/PSA cartridge. The SAX/PSA cartridge was washed with acetone-hexane (2 : 8), and PM was eluted with acetone-hexane (3 : 7).
    If required, the eluate of the Florisil column was cleaned up with SAX/PSA and ENVI-Carb/NH2 cartridges. The SAX/PSA cartridge was washed with acetone-hexane (2 : 8), and connected to be ENVI-Carb/NH2 cartridge. The cartridges were washed with acetone-hexane (3 : 7), and then the SAX/PSA cartridge was removed. PM was eluted with acetonitrile-toluene (3 : 1) from the ENVI-Carb/NH2 cartridge.
    PM in the eluate was separated isocratically on an ODS column (4.6 mm i.d.×150 mm, 5 μm) using acetonitrile-water (6 : 4) as a mobile phase (flow-rate 1.0 mL/min, temp. 40°C), with monitoring at 235 nm.
    The calibration curve was linear from 0.005 μg/mL to 10 μg/mL of PM. The recoveries of PM from eight kinds of agricultural products spiked at levels of 0.1 and 0.02 μg/g were 80.8-98.7%. The determination limit was 0.01 μg/g.
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  • Mitsuo NAKAZATO, Hiroko MATSUMOTO, Yoko KASUYA, Kazuo YASUDA
    2005 Volume 46 Issue 6 Pages 282-285
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    A method for the determination of 4-hexylresorcinol residues in prawn and crab meat by HPLC was developed.
    4-Hexylresorcinol in prawn and crab meats was extracted with methanol using a homogenizer. The extract was diluted 4 times with water, and the diluted solution was passed through a C18 cartridge. The cartridge was washed with water and methanol-water (4 : 6), and then 4-hexylresorcinol was eluted with acetonitrile-0.1% phosphoric acid (55 : 45). The eluate was separated on a Capcell Pak C18 MG column with a mobile phase of acetonitrile-0.1% phosphoric acid (6 : 4) and 4-hexylresorcinol was determined with a UV detector (210 nm).
    Recoveries of 4-hexylresorcinol from commercial prawn and crab meats spiked at 1.0 and 10 μg/g were 82.4-92.2 and 88.9-91.8%, respectively. The determination limit of 4-hexylresorcinol was 1.0 μg/g in the samples.
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Reports
  • Kazuhiro FUJITA, Hironobu ITO, Takahiro YAMAGUCHI, Satoshi YONEYAMA, K ...
    2005 Volume 46 Issue 6 Pages 286-289
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    Inter-laboratory validation studies were conducted in 5 laboratories to validate the biological method for determination of tetracyclines in royal jelly. Oxytetracycline spiked at the levels of 0.2 and 1.0 ppm was analyzed. Mean recoveries were 88 and 90%, reproducibility relative standard deviations (RSDR) were 13.7 and 7.8%, and HORRATR values were 0.7 and 0.5. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 73 and 77%, RSDR were 12.6 and 10.5%, and HORRATR values were 0.6 and 0.6. The determination limit was 0.1 ppm (oxytetracycline, tetracycline) and 0.02 ppm (chlortetracycline). These results show that this method has good performance.
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  • Kazuhiro FUJITA, Keiko AKITA, Takahiro YAMAGUCHI, Satoshi YONEYAMA, Ki ...
    2005 Volume 46 Issue 6 Pages 290-293
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    Inter-laboratory validation studies were conducted in 6 laboratories to validate the biological method for determination of streptomycin in royal jelly. Streptomycin spiked at the level of 0.2 and 1.0 ppm was analyzed. Mean recoveries were 89 and 96%, reproducibility relative standard deviations (RSDR) were 15.0 and 14.0%, HORRATR values were 0.7 and 0.9. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 113 and 99%, RSDR were 15.0 and 10.4%, and HORRATR values were 0.8 and 0.6. The determination limit was 0.1 ppm. These results show that this method has good performance.
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  • Kazuhiro FUJITA, Hiromi OSUKA, Takahiro FUJIKI, Satoshi YONEYAMA, Kiyo ...
    2005 Volume 46 Issue 6 Pages 294-297
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    Inter-laboratory validation studies were conducted in 6 laboratories to validate the analytical method for determination of chloramphenicol in royal jelly. Chloramphenicol spiked at the levels of 0.1 and 0.5 ppm was analyzed. Mean recoveries were 89 and 89%, reproducibility relative standard deviations (RSDR) were 10.5 and 6.8%, HORRATR values were 0.5 and 0.4. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 89 and 84%, RSDR were 9.8 and 12.3%, and HORRATR values were 0.5 and 0.7. The determination limit was 0.05 ppm. These results show that this method has good performance.
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  • Naoyuki SATO, Keiko ISHII, Akio SATOH, Yasuo TANAKA, Toshio HIDAKA, No ...
    2005 Volume 46 Issue 6 Pages 298-304
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    Fifty-two samples of broiled eels and broiled eel liver were analyzed for total mercury (total Hg) and methyl mercury. The mean concentrations of total Hg in broiled eels and broiled eel liver were 0.21 ppm and 0.10 ppm, respectively. Meanwhile, the mean concentrations of methyl mercury in broiled eels and broiled eel liver were 0.085 ppm and 0.039 ppm, respectively. The rate of methyl mercury to total Hg mainly ranged from 60 to 80% in broiled eels and from 35 to 65% in broiled eel liver. The total Hg concentrations of 2 samples of broiled eels and one sample of broiled eel liver exceeded the provisional regulation limit (0.4 ppm) of total Hg in fish in Japan. In these samples, the rates of methyl mercury to total Hg were lower than 20%. The muscles and the skin of broiled eels were measured separately. The ratios of skin to muscle concentration of total Hg and methyl mercury were mainly in the range from 1/10 to 1/4. The mean intakes of total Hg from broiled eels and broiled eel liver per individual were 24.6 μg and 3.1 μg, respectively. The mean intakes of methyl mercury from broiled eels and broiled eel liver per individual were 10.4 μg and 1.2 μg, respectively.
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  • Yumi AKIYAMA, Naoki YOSHIOKA, Keiko ICHIHASHI
    2005 Volume 46 Issue 6 Pages 305-318
    Published: December 25, 2005
    Released on J-STAGE: January 21, 2009
    JOURNAL FREE ACCESS
    During a 3-year monitoring survey (April 2002-March 2005) of pesticide residues in agricultural products, 592 samples (324 domestic; 268 imported) collected in Hyogo prefecture, Japan were analyzed. The number of pesticides tested increased from 232 in FY 2002 to 323 in FY 2004. The purpose of the study was to clarify the residue status by accumulating information about pesticides detected frequently, to allow effective and efficient regulation under the new “Positive List” legislation to be implemented in FY 2006. Overall, 47% of domestic and 61% of imported samples contained detectable residues and ca. 60% of positive samples contained multiple residues. The limit of quantitation was set at 0.01 μg/g and the limit of detection was 0.001-0.003 μg/g. Most of the residues were present at low concentrations: 80% of the detections in samples excluding imported citrus fruits were <0.05 μg/g. More than 5 different pesticides (>0.01 μg/g) were detected simultaneously in 13 samples. The sum of the ratios of residues to MRLs was calculated as one of the indexes to represent the risk of multiple residues, and they exceeded 100% in 3 imported frozen vegetables; baby kidney bean, spinach, Welsh onion. Samples in violation of the Food Sanitation Law were not found in our survey, but 1.9% of the samples might be in conflict with the new “Positive List” legislation.
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