A gas chromatographic method was developed for the determination of the nitrite ion (NO₂^-) in foods. The method is based on the Sandmeyer reaction.
The procedure can be outlined as follows. (a) Extraction of food by homogenizing it with water at 80°C. (b) Precipitation of proteins by addition of alkaline ZnSO₄ solution and removal of the precipitate by filtration. (c) Diazotization of p-bromoaniline by NO₂^- in the aqueous extract followed by reaction with a solution of copper (I) chloride in hydrochloric acid to form p-bromochlorobenzene. (d) Quantitative determination of the reaction product by gas chromatography, employing an electron-capture detector.
The product yield was more than 90%. There was no apparent interference with this method by dimethylamine, sodium chloride, nitrate ion and so on. Various ham and sausage samples were analyzed by this method and the results agreed well with those obtained by the diazotization-coupling colorimetric method prescribed in the Standard Methods of Analysis for Hygienic Chemists authorized by the Pharmaceutical Society of Japan (1980). The limit of determination of NO₂^- was 0.02μg/g.

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The effect of feeding rats with thermally oxidized rape seed oils (3 levels of deterioration; obtained from manufacturers of fried fish paste) on the lipid peroxidation in the rat liver was investigated. Rats were fed ad libitum for 42 days with diet which contained 20% sample oil.
Regardless of the control tocopherol level, groups fed thermally oxidized frying oil showed increased relative liver weight, TBA-positive substances and GSH content, in proportion to the level of deterioration of the oil, compared with the fresh oil-fed group.
These results suggest that some substances present in thermally oxidized oils act as radical generators in vivo.

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The differences of thermal death characteristics of spores of C. botulinum 62A and B. stearothermophilus subjected to isothermal and non-isothermal treatments were investigated. In the course of non-isothermal treatment (temperature rise at a constant rate of 1 or 4°C/min from ca. 50°C), the survival number of B. stearothermophilus spores decreased almost exactly as theoretically predicted based upon the thermal death time (TDT) parametric values which had been determined preliminarily by conventional isothermal treatment. The survival number of C. botulinum 62A spores heated at a temperature increase rate of 1°C/min decreased along the maximum limit of the predicted thermal reduction curve. The survival number of the same spores lot heated at the rate of 4°C/min decreased in a manner scattered between the minimum and the maximum limits of the predicted thermal reduction curves.
No significant differences in TDT parametric values was observed between isothermal and non-isothermal treatments for the spores examined.

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The effects of dietary administration of polychlorinated biphenyls (PCB) on age-related biochemical changes of lipid metabolism and collagen in rats were studied. The following results were obtained:
1) The depositions of PCB in the organs and tissues examined were highest in the white adipose tissue, and decreased in the order of liver, kidney, testis and brain. The depositions increased with age.
2) The levels of triglyceride and cholesterol in serum and liver lipids increased with age. In groups of rats fed PCB, the liver cholesterol after 12 months of age and the serum cholesterol and β-lipoprotein in 18-month-old rats were significantly increased compared with the control group.
3) The levels of lipid peroxide in serum and liver increased remarkably with age and upon PCB administration.
4) The liberation of hydroxyproline during the thermal contraction of skin in rats decreased with age, but was not affected by PCB administration.

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Various preservatives, such as calcium propionate, sorbic acid, potassium sorbate, dehydroacetic acid, sodium dehydroacetate, benzoic acid, sodium benzoate and isobutyl p-hydroxybenzoate, were examined for their inhibitory effects on the growth and aflatoxin B₁ production of A. flavus and A. parasiticus in sliced bread coated with peanut butter.
Bread containing each preservative was baked and sliced in our laboratory. The peanut butter containing a preservative and one hundred spores of each fungus was coated on the upper surface of a slice of bread (5.5×6.5×1.0cm), and then the slice was incubated at 28°C in a Petri dish for ten days.
Of the eight preservatives, calcium propionate and sorbic acid showed the most inhibitory effects. When bread containing calcium propionate (2.5g/kg) was coated with peanut butter containing sorbic acid (1.5g/kg), the growth was retarded by 48hr (A. flavus) and 72hr (A. parasiticus), while aflatoxin B₁ production was retarded by 72hr (both fungal species) in comparison with the control without any preservative.
Further experiments were performed using nine slices of the bread with ten spores each, in the same manner as described above. Neither growth of the two fungi nor aflatoxin production was observed in these slices, with one exception, in which the fungal growth of the two species and aflatoxin production were retarded by 48hr as compared with the control.

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The determination of residual 1, 3-butadiene (BD) in polybutadiene (PBD) household wrapping films and acrylonitrile-butadiene-styrene (ABS) products was studied.
Samples of 0.5g of PBD films and 1.0g of ABS products were accurately weighed into 20ml volumetric flasks each equipped with a silicone rubber stopper. Cooled tetrahydrofran was pipetted into each volumetric flask until the total volume was 20ml. The flasks were stored in a refrigerator, and when the polymers were completely dissolved, the concentration of BD in each polymer solution was determined by gas chromatography.
The recoveries of added BD from PBD film and ABS sheet in the range of 0.5 to 10.0μg per sample were 91-106% and 81-90%, respectively. The coefficient of variation did not exceed 5%. No BD could be detected in commercial PBD household wrapping films or ABS products such as sheets, chopsticks, ladles and graters.

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The determination of residual 4-vinyl-1-cyclohexene (4-VCy, butadiene dimer) in polybutadiene (PBD) household wrapping films and acrylonitrile-butadiene-styrene (ABS) products was studied
PBD films and ABS products were dissolved in tetrahydrofuran and N, N-dimethyl-formamide, respectively. The concentration of 4-VCy in each polymer solution was determined by gas chromatography and mass fragmentography. The extents of 4-VCy migration from ABS sheet to water, 4% acetic acid, 20% ethanol and n-heptane were measured by mass fragmentography, using selected ion recording at m/e 54.
The recovery of 4-VCy added to ABS sheet was found to be 89.3-103.0% in the range of 40.0-80.0μg per sample, and the coefficient of variation was found to be 5.4%. Commercial ABS products such as sheets, ladles, graters and lunch trays were analyzed and found to contain 14-210ppm 4-VCy.
No 4-VCy migration from ABS sheet to four food simulants was found, though some migration into n-heptane occurred.

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[in Japanese]

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