Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi)

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The additive effect of salts on the bactericidal action of ethanol towards Escherichia coli was investigated.
The salts NaCl, KCl, LiCl and CaCl₂ had no effect on the bactericidal action of 10% ethanol solution but enhanced that of a 20% solution. Their effects were proportional to the concentration of the added salts in the ethanol solution, and increased in the order of LiCl, KCl, NaCl, and CaCl₂.
Differential scanning calorimetry (DSC) thermograms during the heating process were remarkably changed by addition of NaCl. KCl, LiCl, or CaCl₂ to aqueous solutions of ethanol. Half line widths of the water oxygen signal in the ¹⁷O nuclear magnetic resonance (¹⁷O NMR) spectra were also remarkably broadened by addition of NaCl, KCl, and CaCl₂ to 20% ethanol solution, implying a decrease in the degree of molecular freedom. The signal of the hydroxyl proton in the ¹H NMR spectra was shifted to lower magnetic field in the presence of NaCl, KCl and CaCl₂, indicating that the proton was hydrogen-bonded.
It is suggested that the additive effect of salts on the bactericidal action of ethanol towards Escherichia coli might be enhanced through hydrogen-bonding and hydration interactions between water, salts and ethanol.

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Dietary fiber and Trp-P-2-containing diet was administered to rats. Fecal excretion of Trp-P-2 administered with fiber was faster than that in the absence of fiber. Fecal excretion of Trp-P-2 was increased by the diet with either 10% crude burdock fiber or 10% cellulose, although the increment of Trp-P-2 in feces was small as compared with the initially administered dose. The dietary fibers tested did not affect the urinary excretion of Trp-P-2. HPLC chromatograms of feces and urine suggested that major components might be metabolites of trp-P-2. Although the addition of dietary fiber increased fecal volume, this increase did not appear to account for the increase of Trp-P-2 excretion.

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A simple and selective high performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of quinolone antibacterials, which include oxolinic acid (OXA), nalidixic acid (NA), piromidic acid (PMA), miloxacin (MLX) and flumequine (FQ), in fish and meat.
The drugs were extracted with 0.2% metaphosphoric acid-methanol (7:3), followed by a Bond Elut C₁₈ clean-up procedure. The HPLC separation was carried out on an L-column ODS using 0.05M sodium dihydrogenphosphate-acetonitrile (6:4) as the mobile phase. A fluorescence detector was used for OXA, NA, MLX and FQ at the excitation wavelength of 325nm and the emission wavelength of 365nm, and an ultraviolet detector at 280nm for PMA. The calibration graphs were rectilinear from 1 to 20ng for each drug. The recoveries of drugs from fish and meat fortified at 0.5μg/g were 77.9-87.2%, with high precision. The limits of detection were 0.01μg/g for each drug. OXA was found in 7 samples of eel at levels in the range of 0.01-0.1μg/g. A photodiode-array detector was used to confirm identification of residual OXA in eel.

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A method for preparation of sample solution suitable for simultaneous determination of 21 kinds of organophosphorus and carbamate pesticides in agricultural products by FPD and FTD-GC was studied. The residual limits of these pesticides in agricultural products will be legally restricted within this fiscal year in Japan.
Two preparation methods of sample solution were simply and systematically set up according to the degree of food contaminants in sample. For general vegetables and fruits, no special clean-up method was used, and for cabbage, cereals and beans, zinc acetate was used for clean-up (solidification method) of the sample solution.
Organophosphorus pesticides spiked at 0.2ppm and carbamate pesticide spiked at 0.4ppm in 11 kinds of samples gave recoveries in the range of 60.4-105.2% by the proposed method.
Surveillance for 21 kind of residual pesticides in imported foods was carried out, and 49ppb of malathion and 55ppb of carbofuran were found in wheat (USA) and in lemon (USA), respectively.

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