An advanced method of determination of hydrogen peroxide in foods has been investigated. Hydrogen peroxide in sample was extracted with two times volume of methanol. 1ml of the extract containing hydrogen peroxide was transferred into a 20ml of test tube, and 3ml of distilled water and catalase solution (2, 000 I. U.) were added to the extract in the test tube and warmed for 15min at 37°C to produce the formaldehyde quantitatively. Then 1ml of 0.4% 3-methyl-2-benzothiazolone hydrazone hydrochloride solution was added into the test tube and warmed again for 25min at 37°C, and 5ml of 0.2% ferric nitrate solution was added, then the test tube was allowed to stand for 5min at room temperature for complete development of the color. The reaction mixture was diluted to 20ml with acetone. The absorbance of the solution was determined at 635nm of the wave length. Under the condition described above, it was found that the hydrogen peroxide in some kind of food could be determined with recovery 97-107% and variation coefficient of about 5%.
The determination of migrated styrene monomer (SM) and ethylbenzene (EB) in foods by mass fragmentography was studied. The apparatus for the extraction of the migrated substances used was an essential oil distillator shown in Fig. 1. The samples such as noodle-soup and sour milk beverage packed in polystyrene cup. After the sample was placed in a flask, extracting flask was heated in a mantle heater for 60min, using n-pentane as the solvent to collect the migrated substances. After distillation, n-pentane layer was transferred in a small test tube quantitatively, SM and EB were determined by mass fragmentography. The recoveries of SM and EB in noodle-soup and sour milk beverage by the proposed method were at least more than 90%. Analysis of SM and EB in food was simplified by this method, beside the migrated substances were determined without any influences of obstructive substances.
An attempts was made to elucidate the substances formed in rice cultures of a trichothecene-producing strain of Fusarium roseum No. 117 (ATCC 28114) that caused feed refusal to rats. After 15 days of incubation at 25°C, concentrations of deoxynivalenol (3α, 7α, 15-trihydroxy-12, 13-epoxytrichothec-9-en-8-one, DON) and 3-acetyldeoxynivalenol (3α-acetoxy-7α, 15-dihydroxy-12, 13-epoxytrichothec-9-en-8-one, 3-Ac-DON) reached to about 220μg and about 160μg per g of rice, respectively. Additionally, a trace amount of a new trichothecene, 3α, 15-diacetoxy-7α-hydroxy-12, 13-epoxytrichothec-9-en-8-one was also isolated. The greater part of the feed-refusal activity of the inoculated rice seems to be in the fraction containing above trichothecenes, but participation of other substances was not ruled out. Comparing two-day feed consumption as % of control, medium effective doses of pure DON and 3-Ac-DON were about 100μg and about 150μg per g of feed, respectively. Gain in the body weight of rat was completely inhibited with diets containing 150μg of DON or 200μg of 3-Ac-DON per g, receiving about 4mg of DON or about 7mg of 3-Ac-DON per kg of body weight.
Chemical analysis of human milk and adipose tissues obtained from a woman who had been exposed to the polychlorinated biphenyls (PCB) was conducted to study the contamination and metabolites of PCB in a human body. The methylsulfonated PCB (metabolites of PCB) were found in the milk and adipose tissues. Gas chromatograph-mass spectrometric analysis has demonstrated that the methylsulfones of PCB from the human milk were tetra-, penta- and hexa-chlorinated compounds. The concentration of methylsulfones of PCB in the milk and the adipose tissues were estimated to be 0.16-0.79ppm, which corresponded to approximately 1/20 levels of the PCB present in the respective materials.
In the preceding paper, we reported that the antibacterial action of hexametaphosphate (HP) was enhanced in the presence of surface-active agents such as cholate (CA) and monocaprin and others. The mode of synergistic action of CA on HP was investigated using Escherichia coli, and some results as given below were obtained. Though the O2-uptake of E. coli could not be inhibited by the addition of CA or HP alone, HP showed the inhibitory effect when CA was added prior to HP. When these drugs were added in reverse order, HP did not inhibit the O2-uptake of E. coli. In addition, HP masked with Calcium ion did not show the inhibitory effect of O2-uptake even if CA was added prior to HP. While HP hardly acted on the spheroplast of E. coli, CA acted vigorously on the spheroplast and accelerated the cell-lysis. As a result of the cell-lysis, the viscosity of the medium rapidly increased. Although CA acted on E. coli and released the substances which show absorbance at 260nm, neither a marked release of the cell components from E. coli nor the cell-lysis of the spheroplast by HP-treatment was observed. From the result of the previous and this paper, one of the mechanism of the synergistic action of CA on the antibacterial action of HP was deduced that CA acts on the cell envelope of E. coli, alters the permeability barrier, continues to keep the state as it is, and the action of HP on E. coli is particularly enhanced under this condition.
A survey on distribution of enterotoxin-producing strains of Clostridium perfringens in the sea muds at 10 stations in the inner part of Ariake Bay and in the muds at the nine rivers running into the bay has been made. In addition, sporulating-ability of the isolates has been estimated, and tests for heat resistance and serotypes of the isolates have been made. Enterotoxin-producing strains were isolated from the muds at 8 stations in the bay and from the muds at the two rivers. Enterotoxin producibility of a majority of the enterotoxin-producing strains from the bay muds was higher than that of the strains from the river muds. Ten of 62 isolates from the bay muds were enterotoxin positive, and only two of 38 isolates from the river muds were the positive. Twelve of 46 strains which were both sporogenous and heat-resistant (100°C, 10min) were enterotoxin positive. Four of 12 strains which were enterotoxin positive belonged to Hobbs' type and the remaining 8 strains were untypable. Four strains of the typable 13 strains were enterotoxin positive.
A simple method for determination of zearalenone in the culture of Genus Fusarium and cereal by gas chromatography equipped with a flame ionization detector (FID-GC) was investigated. The presented method was composed of the following steps: Sample was extracted with methanol. To the methanol extract 1% sodium chloride solution was added. The aqueous methanol was defatted with n-hexane and was reextracted with chloroform. After the chloroform extract was cleaned up by column chromatography using a silica gel and Florisil mixture, zearalenone was silylated with N, O-bis (trimethylsilyl) trifluoroacetamide in ethyl acetate. The TMS-derivative was determined by FID-GC with a column (3mm×1m) of 2% OV-1 on Gaschrom Q. The recoveries of zearalenone added to cereals at level of 0.4ppm were from 71.8 to 87.6%. By this method, zearalenone was determined in the range of 4-3051μg/g in the culture of Fusarium species and was not determined in wheat and barley of Saitama growth in 1975, although zearalenone producing strain were isolated three strains from the wheat.
Solutions of 54MnCl2 (0.5mg manganese chloride/kg, low dose; 10mg manganese chloride/kg, high dose) were intravenously injected to groups of pregnant rats on the 10th, 13th, 17th and 19th days of gestation, and the manganese distribution in maternal and fetal tissues were examined 3 hours after each injection and on the 20th day of gestation. Three hours after the injection, placental distribution of the metal was predominantly higher in the 19th and the 17th days treated groups than in the 13th and the 10th days groups. However, the difference related to the stage of gestation was not evident concerning the manganese distribution in other maternal organs. The stage-linked difference of manganese distribution was also not recognized in fetal whole body. The distribution pattern of the metal in the whole body of pregnant rats at the 20th day of gestation showed rather rapid decrease in the high dose group than in the low dose group. In maternal brain, bone and ovary of both dose groups, accumulation and/or slow elimination of manganese was observed. In all of the fetal organs of both dose groups, the earlier the stage of administration, the lower the distribution of manganese was observed, and, as compared with the maternal organs, remarkably higher concentrations of the metal were detected in fetal brain, heart, lung, liver and bone in the groups treated after the 13th day of gestation.
Mutagenicity of food pyrolysates was investigated utilizing a microbial system. Foods were respectively pyrolyzed at 200°C, 250°C, 300°C, and 400°C for 10 minutes in electric furnace, and were extracted with chloroform/methanol (1:1). Mutagenicity of the extract was tested by Ames method using Salmonella typhimurium TA98 and TA100 with or without S-9 mix. Mutagenicity was mostly detected only with S-9 mix in 36 of 50 food pyrolysates. The mutagenic activity began to appear in pyrolysate at 250°C and reached to highest activity in pyrolysate at 300°C or 400°C. In addition, it was found that there was a correlation between mutagenic activities of pyrolysates and protein contents in the food. In general, it has been reported that there was a high correlation between mutagenicity and carcinogenicity. Therefore, it might be indicated that appearance of mutagenicity in the proteinous food pyrolysate present a new subject in food safety problems.
The effects of pyrocatechol, pyrogallol, 4-methylcatechol (4-MC), and gallic acid (GA) on the nitrosation of diethylamine were studied. At pH 3 and 37°C, all 4 polyphenols in concentrations more than 5mM inhibited the nitrosation. In low concentrations, no effects were observed. At pH 4, the effects of all polyphenols except GA were similar to those at pH 3. However, 20mM of GA somewhat accelerated the nitrosation. The effect of pH was examined with 10mM of 4-MC. 4-MC inhibited nitrosodiethylamine formation at pH 2.0-4.5.
About 30-60μCi/0.15mg Cd/kg of cadmium chloride solution containing 115mCd was injected intraperitoneally to mice, rats, guinea pigs, rabbits and quails, and thereafter the whole body retention of Cd was measured continuously for 60-92 days in order to find the biological half lives of the metal in these animals. The whole body retention was determined by whole body counting of radioactivity in mice, rats, guinea pigs and quails, but in the case of rabbit it was determined by counting rates of excreta. The biological half lives thus obtained in mouse, rat, guinea pig, rabbit and quail were 220, 150 and 181, 334, 299 and 367 days, respectively. Namely, an apparent species difference was observed even under the same conditions such as sex of animal, dose of metal per kg and dosing route.