A colorimetric method for the determination of dulcin was established. According to this procedure, 2ml of 3% p-dimethylaminobenzaldehyde (DMAB) in 1N HCl-alcohol solution was added to 2ml of dulcin solution. The colored solution had an absorption maximum at 440mμ and the absorption spectra were found to follow the Lambert-Beer's Law within the range of 2-40μg/ml in dulcin concentration. Thereafter, the determination of dulcin in foodstuff was attempted by the application of this method. Interferences from foodstuff ingredients has been minimized by means of dialysis and extraction with ethyl acetate.
Low molecular substances produced by the hydrolysis of sodium carboxymethylstarch (Na-CMS, degree of substitution: 0.38) with saliva amylase were studied. Na-CMS was hydrolyzed with human saliva amylase, and the hydrolyzates were fractionated by Sephadex column to No. 1-5 portions. The fraction 1 showed a different behavior from the other fractions on paper chromatogram, and it was colored to violet (absorption maximum: 540mμ) by heating with 0.01% 2, 7-dihydroxy-naphthalene sulfuric acid solution in water bath. Infrared spectrum of the fraction showed the absorption of carboxyl group. These facts revealed the presence of a carboxymethyl group in the fraction 1, but in the fraction 2-5, respectively carboxymethyl group was not identified. The fraction 1 was not colored with iodine, and the average polymerization degree of the fraction 1 was 7.5 by the determination with 3, 5-dinitrosalicylic acid method.
Freshly dissected livers from 12 days-old chicken embryo were prepared for primary culture. After trypsinizing, the cells were grown as monolayers in bottle culture on glass coverslips at 37°C using Eagle's minimal essential medium supplememted with 5 percent calf serum, 100 units/ml penicillin, and 100μg/ml streptomycin. In the presence of aflatoxins the characteristic cytological change was a marked quantitative decrease of the liver parenchymal cell nucleoli. The mesenchymal cells, on the other hand, were less sensitive to the toxic agents. It has been pointed out that the characteristics of enzyme inhibition by aflatoxins resemble those by actinomycin D. The culture cells treated with actinomycin D revealed that the mesenchymal cell nucleoli can scarecely be recognized and, on the other hand, there are distinct nucleoli in the parenchymal cells. Some specimens which had been identified as aflatoxin B1 with either physical or chemical methods were tested by this “New bioassay method”. The characteritic nycleoli changes were observed in the parenchymal cells at 1μg/ml within 24hrs. It is agreed with previous reports that the partial changes of chemical structure of aflatoxins, for instance aflatoxin B2 or tetrahydrodesoxo aflatoxin, encountered the different toxicities to the cell-system. From above mentioned facts, it might safely be said that the present chicken embryo liver cell-system could be useful for the bioassay method of aflatoxin B1.
Glycine is distributed widely in animal and plant materials, and contributed to the taste of crab, shrimp, sea urchin, etc.. As glycine has been employed for seasoning fish jelly products such as KAMABOKO, CHIKUWA, etc. in Japan, the effect of this amino acid to microorganisms was investigated. Most of the bacteria tested were inhibited by addition of 1 to 5 percent of glycine, but yeasts and molds were not. It is of interest from the viewpoint of food preservation that the spore-forming bacteria were inhibited by glycine. The derivatives of glycine and the other amino acids did not exhibit any effect on the microorganisms. The patterns of inhibition were somewhat different from strain to strain. Growth induction of Bacillus subtilis was prolonged by addition of glycine. On the contrary, the maximum growth of Achromobacter delmarvae was suppressed by increasing the concentration of glycine. Furthermore, the preservation period of KAMABOKO was prolonged 3 days or more by addition of glycine in comparison with the controls. Judging from these facts, glycine may be used as a food preservative.
Using two sorts of microbes, in order to simplify the discrimination between bacteriostatic and bactericidal action, seven officially authorized food preservatives and antimicrobials-benzoic acid, sodium benzoate, salicylic acid, sorbic acid, potassium sorbate, chloramine B and AF-2-were examined by the multiple dilution and methylene blue dyeing method and the following results were obtained. 1) The discrimination of bacteriostatic or bactericidal action was made more accurately by comparing figures of γ ratio-total cell number (TCN) to methylene blue dyed dead cell number (DCN) -in each concentration of preservatives and antimicrobials. 2) The γ values from several testing media enabled us to presume a certain correlation-ship between the food additives and their rules of usage. 3) The influence of pH on acidic preservatives was the same as that of the previous report. Comparing with the results of previous papers, it is ascertaind that the chlorella method is more convenient than that of saccharomyces for the toxicity test of food additives and the twice dilution method is appropriate for the test.
A colorless crystalline substance was produced from dulcin dissolved in water by boiling. This substance was proved to be different from dulcin as results of taste, melting point, UV absorption spectrum, IR absorption spectrum and elementary analysis, and it was regarded as didulcin. When the aqueous solution of dulcin was heated at different temperatures, dulcin was unstable at high temperature, however, it was not changed below 60°C within about one hour.
The experimental conditions for the determination by dialysis method of dulcin in foods were studied. A result it was confirmed that the dialysis speed of dulcin in foods was accelerated by addition of sodium chloride into the solution to be dialyzed. Further, for extraction dulcin dissolved in the dialyzed solution with ethyl acetate, the addition of sodium chloride was effective to accelerate transfer of dulcin into ethyl acetate. The reappearance of color produced by diazotation method and p-dimethylaminobenzal-dehyde method were experimented, and it was found that the latter method was superior to the former. The results above mentioned were applied to the determination of dulcin in market foods.
Enterococci were obtained from 338 samples (71%) of 464 materials of flies and cockroaches. Of these samples examined, enterococcal strains were isolated at high level (87%) from intestinal contents of cockroaches. The bacterial counts of enterococci in samples tested were at the level from 102 to 107 per sample. Of these, enterococcal counts of the bodies (including the intestinal contents) were much more than those of the legs. According to biological properties, the majority of the isolates were identified as Str. faecium (type BII, reported by Shimazaki et al.). Most of the remainders were classified as Str. faecalis and Str. faecalis var. liquefaciens (type AII, the same reporter) and only a few strains showing the beta-haemolysis were detected. Furthermore, some strains among the isolates could not be identified clearly.