A simple method to detect glyphosate (PMG: (N-phosphonomethyl) glycine) and its metabolite (AMPA: aminomethylphosphonic acid) in fruits and vegetables by high performance liquid chromatography with a fluorescence detection was developed. PMG and AMPA were extracted from fruits and vegetables with water, and the extracted solution was washed with chloroform. The water layer was further purified on a cation exchange column, and the isolated PMG and AMPA were derivatized with 9-fluorenylmethylchloroformate (FMOC). The reaction products in the water layer were rinsed with ethyl acetate and then measured by high performance liquid chromatography with a fluorescence detection. The recoveries of PMG and AMPA added to fruits were above 68 and 88% at 0.1ppm and 1.0ppm, respectively. Detection limits were 0.05ppm. This method is applicable for routine analysis of PMG and AMPA in fruits and vegetables.
Two types of intoxication, caused by intake of carp gallbladder or mainly its muscle (Sasimi), have been reported. In order to identify the substances responsible for these carp intoxications, we initially examined the distribution of toxin in normal carp viscera and muscle by means of an acute toxicity test in ddY male mice (19-20g). It was found that the toxic substances were in gallbladder and liver-pancreas, especially bile, but not muscle. Thus, intoxication by carp gallbladder could be attributable to components normally present in carp bile. Based on the LD50 values, it was concluded that essentially all of the bile toxicity can be explained by the toxicity of cyprinol sulfate, a major component of carp bile. Furthermore, the acute toxic symptoms induced by raw bile and cyprinol sulfate were similar. On the other hand, from the result of a 50% hemolysis test, it was found that some bile acids contained in raw bile were more hemolytic than cyprinol sulfate. Taking these results into consideration, it was suggested that carp intoxication resulting from ingestion of the gallbladder could be caused by not only cyprinol sulfate but also other components, especially bile acid.
The fate of 4 kinds of aflatoxins, aflatoxin B1, B2, G1 and G2, during cooking processes, especially boiling, were investigated. The samples, in which aflatoxin contamination was found in our survey, were cooked to evaluate the behavior of aflatoxins during the cooking process so that we could better estimate the real intake of aflatoxins from those aflatoxin-contaminated foods. Using corn, buckwheat, adlay, nutmeg and white pepper naturally or artificially contaminated with aflatoxins, we cooked porridge from the corn and adlay, and used the nutmeg and white pepper as seasoning in sauteing and making soup. Sixty percent or more of aflatoxins remained after any one of the cooking processes, and there was no significant difference among the 4 aflatoxins in rate of loss. In other words, the aflatoxins could not be effectively degraded or eliminated in either sauteing or boiling processes. In spite of the fact that the degradation rate of aflatoxins contained in foods was found to be 10-30%, other data show that more than 80% of aflatoxins are degraded by boiling them alone, which seems to suggest that some compounds exist in food that protects aflatoxins. We also studied this point and confirmed that such a protective effect is exerted by reducing saccharides (such as glucose), proteins and amino acids, but not inorganic salts.
The transfer of auxins to cultures of organisms that could be used to produce food colors was studied by radiochemical techniques. In all cases, cells producing pigments were selected for the studies. Cells of Phytolacca americana and Glycyrrhiza glabra were incubated with [2-14C] -2, 4-dichlorophenoxyacetic acid (2, 4-D) for 72hr and 33 days, respectively. Cells of Rubia tinctorum were incubated with [2-14C] indole-3-acetic acid (IAA) for 20 days. Distributions of radioactivity following the incubation of cultured cells were studied. The results may be summarized as follows. 1) The uptake of 2, 4-D was faster than that of IAA. 2) Even in the long-term studies, more than 40% of radioactivity derived from auxins remained in the tissues, though the proportion of metabolites increased. 3) IAA was metabolized faster than 2, 4-D and a considerable amount of IAA metabolites was transferred to the cell residual fractions. 4) Intracellular 2, 4-D or IAA is extracted with the solvent which is usually used for the extraction of the pigments. 5) Since the extract of pigments contained auxins and their metabolites, it would be necessary to purify the extract before utilizing the pigments as food colors.
A plasmid (pYM3) carrying a fused gene ada'-'lacZ was introduced into Salmonella typhimurium TA1535 to give a strain designated TA1535/pYM3. Using this strain and the strain TA1535/pSK1002 (umuC'-'lacZ), the activity of β-galactosidase induced by DNA-damaging agents was measured by a fluorometric assay. This strain responded only to alkylating agents such as N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). The sensitivity of fluorometric assay was compared to that of the original colorimetric assay. It was found that the sensitivities were almost equal, but that the amount of substance required in the assay was about thirty times less. The fluorometric umu- and ada-test was also employed for the detection of mutagens in food, in comparison with the Ames test. Japanese chopped ham was tested for mutagenic activity after nitrite treatment and fractionation. All fractions gave positive results in this sensitive fluorometric assay and in the Ames test. The fluorometric umu- and ada-test is advantageous for assaying small amounts of various food samples. The ada-test may be useful for the screening of potential DNA-methylating agents in food samples.
In recent years, many incidents of food poisoning by carp have been reported. It is important to determine the nature and amounts of the causative substances. Accurate determinations of cyprinol, one of the causative substances, and some bile acids were examined. Cyprinol and cholic acids were extracted from bile and muscle of carp. After alkalysis and derivatization of cyprinol, etc., analysis was carried out by FID-GC equipped with a fused silica methyl 50% phenylsilicone capillary column (25m×0.32mm i. d., 0.25μm film thickness). GC conditions were as follows: the sample was injected into solvent-cut injector and solvents were removed for 2 minutes at room temperature. The column temperature was programmed from 200°C to 260°C at 8°C/min. The injection temperature was 280°C. The detection limit of cyprinol was 5ng, and those of cholic acid, etc. were 3ng, based on the amount giving a signal equal to 3 times the amplitude of the baseline noise.
A high performance liquid chromatographic method for the simultaneous determination of the cyanogenic glycosides, i. e., amygdalin (AM) and prunasin (PR), and their degradation products, i. e., benzaldehyde (BAL) and benzoic acid (BA), in processed foods containing ume (Japanese apricot Prunus mume Sieb et Zucc.) was developed. The sample was extracted with 0.05M citric acid solution and cleaned up by use of a Seppak C18 cartridge. The extract was chromatographed on a Capcell Pak C18 SG120 column with acetonitrile-water-0.2M phosphate buffer, pH 4.0 (16: 79: 5). Detection was achieved with a UV monitor set at 210nm. The peaks corresponding to AM and PR were confirmed by examination of the effect of emulsin treatment. The recoveries from ume extract, umeboshi (dried and salted ume), umeshu (Japanese apricot wine) and ume jam fortified with AM, PR, BAL and BA at levels of 40-100μg/g each were 86.9-100.6% (C. V. 3.7-7.7%) for AM, 69.9-105.3% (0.9-4.2%) for PR, 71.9-85.0% (1.8-2.6%) for BAL and 82.7-99.1% (0.8-4.8%) for BA, except for AM in the ume extract and the umeboshi. AM in ume extract and umeboshi could not be determined owing to interference by contaminants. The determination limits were 10μg/g for AM, 2μg/g for PR, and 1μg/g for BAL and BA, respectively.