Bacterial examinations were carried out on raw noodles, boiled noodles and swabbed samples of utensiles and equipments of noodle-factories in Osaka city, and as well as preservation tests on boiled noodles.
Of the raw or boiled noodle samples, 81.1% showed less than 10³ CFU/g, thus bacterial contamination was comparatively low. However, total coliforms and Staphylococcus were found in 22.2% and 5.6% of the boiled noodles, respectively.
Micrococcus was the dominant species of microflora in raw noodles, but the microflora of boiled noodles was composed of Micrococcus, Staphylococcus, as Acinetobacter, Moraxella and etc.
In the preservation test of boiled noodles, significant bacterial growth was not observed at 5°C even after 3-day-incubation, but at 20°C, the bacterial count reached 10⁸ CFU/g, after 1-day incubation. At 35°C the sample was completely putrefied with 10⁸∼10⁹ CFU/g.
The bacterial assay of swabbad samples indicated that the contamination was caused by cooling bathes and Micrococcus, Flavobacterium and Moraxella were the dominant microflora.
These findings indicate the importance of sanitary control in noodle factories, in particular cooling bathes, and low temperature control in the marketing process.

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The effects of pH on botulinal toxin production in boiled rice and the heat resistance of the spores were investigated. Toxin was detected in boiled rice (pH above 5.0) packed in a plastic film pouch or semi-rigid plastic tray with deoxidant and inoculated with mixed spores (ca. 10⁶ per container) of Clostridium botulinum 62A, 90A, 213B and B1G4 strains following incubation for one to six months at 30°C. Lowered pH (5.0) and cooking, for 19 min at 99°C, failed to prevent toxigenesis. The heat resistance of C. botulinum spores in rice gruel (pH 5.3) was assessed. D (decimal reduction time at 100°C) and z (a slope index of the thermal death time curve) were 9 min and 10°C for 62A, and 7 min and 9°C for 213B, respectively. Raw rice was also examined for contamination with clostridial spores. No clostridial spores could be found in milled rice grains. The number of spores per 100 g was 3 to 73 CFU for brown rice and more than 100 CFU for bran.

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The antibacterial actions of soy sauce, sawa-wasabi, ginger and garlic on the viability of Vibrio parahaemolyticus were examined mainly at 5°C. Sawa-wasabi acted most strongly and rapidly of these spices, only in soy sauce, and not alone. Allylisothiocyanate, the main pungent component of sawa-wasabi had the same action as sawa-wasabi. Ginger had a strong inhibitory action by itself, but showed no synergy with soy sauce. Garlic did not exert its action even in soy sauce. The antibacterial mechanism of soy sauce is suggested to be due at least to the co-operation of its pH (4.5-4.7), Aw (below 0.9) and the content of sodium chloride (10-18%).

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Recovery of Salmonella Typhimurium using a new Nissui Salmonella Food Stamp from artificial inoculated tile, stainless steel, rubber sheet, and wood was compared with the standard swab methods. The correlation coefficients between CFU of spread bacterial number and CFU by the Nissui Salmonella Food Stamp were as follows: tile; 0.91 (n=175), stainless steel; 0.93 (n=59), rubber sheet; 0.94 (n=99), and wood; 0.90 (n=63).

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ArylsulfataseandPyrazineamidase activitiesandindoxylacetatehydrolysiswereexamined in a total of 99 Campylobacter and Helicobacter strains belonging to the following species; C. jejuni, C. coli, C. fetus, C. hyointestinalis, C. lari, “C. lari variant”, C. upsaliensis, C. sputorum, H. cinaedi, H. fennelliae, H. pylori and H. mustelae, “C. lari variant”, C. sputorum and H. cinaedi gave positive results in the arylsulfatase test. C. jejuni, C. coli, C. jejuni subsp. doylei, “C. lari variant” and C. sputorum biovar fecalis gave positive results in the pyrazineamidase test. All strains of C. jejuni, C. coli, C. upsaliensis and H. mustelae were positive for indoxyl acetate hydrolysis, whereas C. fetus, C. hyointestinalis, C. lari, C. sputorum, H. cinaedi and H. pylori were negative. These tests provided to be valuable methods for the phenotypic identification of Campylobacter spp. and relative organisms.

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[in Japanese]

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