The inhibitory effect of different food dyes, which are used for food additives at present, on pancreatic amylase was examined in vitro, following the establishment of assay method of the enzyme activity in the presence of the dyes.
The preincubation of enzyme and dye for a certain time was prerequisite for the appearance of inhibitory effect of the dye. Xanthene dyes except acid red showed the significant inhibition at the wide range of pH, which degree increased in order of eosine, erythrosine, phloxine and rose bengale. No other dyes tested except xanthenes inhibited the enzyme at neutral pH, whereas most of them showed the inhibition of 20 to 70% at pH 4.0.
The inhibitory effect of rose bengale was strongly enhanced by irradiation of the preincubation mixture under a fluorescent lamp, suggesting a photo-inactivation of the enzyme by this xanthene dye. The inhibition was also influenced by the co-existence of other substances; for example, sodium chloride stimulated the inhibition and sucrose and proteins repressed it. From the kinetie study, the type of inhibition of pancreatic amylase by rose bengale was non-competitive.

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In order to obtain a breaf information albout extent of Contamination of foodstuffs by fungi especially by Aspergillus flavus which is known to produce aflatoxin, fungal and bacterial examination of flours and cereals on sale, such as buckwheat flour, wheat flour, roasted soybean flour, soybean and peanut, were carried out. Isolated fungi were identlfied and aflatoxin productivity of A. flavus found among them was studied.
Test material was suspended and homogenized in phosphate buffer saline and mix-cultured in potato dextrose agar containing chloramphenicol. After 7 days incubation at 27°C, number of the colonies of fungi and yeasts developed were counted. Fungi and yeasts were found from 77% of the materials tested over all; and 100, 90, 45.5, 78.9 and 73.3% from buckwheat flour, wheat flour, roasted seybean flour, soybean and peanut, respectively. Number of fungi and yeasts in average in each foodstuffs tested were as follows: 23, 000/g in buckwheat flour, 240/g in wheat flour, 90/g in roasted soybean flour, 130/g in soybean and 280/g in raw non-shelled peanut.
Bacterial counts made on plain agar were as follows: 170, 000/g in buckwheat flour, 860/g in wheat flour, 130/g in roasted soylbean flour, 400/g in soybean and 540/g in raw nonshelled peanut. Degree of fungal contamination did not correlate with that of bacterial contamination. Moisture contents of the test materials also showed no correlation with degree of fungal or bacterial contamination.
The most prevaling genus among isolates of fungi was Penicillum (43.8%) and next one was Aspergillus (24.0%). In addition to them, Cladosporium (6.3%), Rhizopus (3.1%), Cephalosporium (2.1%), Scopulariopsis (2.1%), Epicoccum (2.1%), Paecilomyces (2.1%), Mortierella (1.0%), Gonatobotrys (1.0%), Botrytis (1.0%), Monilia (1.0%) and Mucor (1.0%) were also isolated.
Among 23 strains of the isolates of Aspergillus, 10 were identified as A. flavus, of which 7 were isolated from buckwheat flour and the others were from wheat flour. Five strains of them were proved to elaborate aflatoxin B₁ and/or B₂ in vitro. Most of them produced the toxin only in a small amount, but one strain which was isolated from wheat flour produced toxin B₁ in fairly large amount. It was estimated to be 23.2mg/kg of the mold rice medium by fluorodensitometric method. Toxicity of this toxin was tested by chicken embryo method. The value of LD₅₀ was 0.125μg/Egg.
Aflatoxin itself was not detected directly in the material from which A. flavus was isolated.

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It is well known that flea seed husk contains about 64% of non-digestible polysaccharide and also this husk has some laxative action. Then the nutritional studies of this husk were undertaken to confirm its suitability as dietetic food.
For the experiment, 60 male rats were divided into three groups, namely, control, 3 and 10% husk added diets groups, and animals were fed for 3 months with these diets and every day the body weight, and weights of feed intaken, of water drunken and also of feces excreted were measured.
The lower body weight gain was observed only with 10% husk added diet group, and 3% group showed almost the same growth as that of control group. By the administration of this husk, the amounts of feces excreted were increased, but there was no sign of diarrhea.
The weight of organ was measured about 10 organs, but there were no significant differences between these weights was of normal and those of 3% group, while these were significant between normal and 10% group.
The histological examination was also done with these organs of three groups, but the evident changes were not recognized.

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腸球菌検査用の選択平板培地としてAE寒天培地 (azide esculin agar) を考案した.
供試腸球菌の221株の中で98.2%が45°においてAE寒天平板上でよく発育し, 24時間以内に黒色の“Halo”を有する特色ある集落を形成した. また冷凍食品の寒天培地検査で出現した定型的集落243個の中で96.3%は腸球菌と同定された.
冷凍食品の腸球菌測定検査において, AE寒天培地を用いた検査術式は正確迅速で実用に供し得ることを認めた.

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市販冷凍魚介類50試料について, 生菌数, デソキシコーレイト寒天による大腸菌群およびAE寒天平板による腸球菌の測定値を比較したところ, 生菌数と腸球菌数の間にはかなりの関連性がみられたが, 大腸菌群数と生菌数あるいは腸球菌数との関連性は低かった.
冷凍魚介類試料において腸球菌に比べて大腸菌群の測定値の低い場合の多いのは, 大腸菌群の方が凍結貯蔵中にすみやかに死滅する点だけでなく, 生残菌の中の大部分がデソキシコーレイト寒天において集落形成能を失うことにもよることを明らかにした.

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1) 過酢酸は核酸塩基ならびにヌクレオシド単独に作用し, その作用はpHに大きく影響され, アデニン, シチジンを除く他の塩基類はpHが高くなるに従って分解されやすくなった.
2) 過酢酸は核酸 (DNA) に対しても作用した. DNAに対する作用の一つはDNA塩基に対する作用であることが塩基分析の結果明らかとなった. このDNA塩基に対する作用は塩基単独の場合とは異なり酸性域で強く作用した. 中性, アルカリ性域では酸性に比べ塩基の分解は小さく, 高濃度過酢酸に対しても比較的安定であった.
3) 過酢酸をDNAに作用させると粘度の低下がみられた. この粘度の低下は二本鎖DNAが一本鎖DNAになることによって起こる粘度低下よりも大きいことから, DNAの切断などの, より大きな変化がDNAに起こっていることを示唆した.

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In Department of Toxicology, National Institute of Hygienic Sciences, chronic toxicity tests using γ-irradiated wiener sausage are carrying out. The authors studied on the fat oxidation in irradiated and non-irradiated wiener sausages mixed in rat feed respectively, and acid value, peroxide value and carbonyl value of crude fat were measured.
Remarkable differences between irradiated and non-irradiated samples were not observed. Peroxide value and carbonyl value of both feed samples changed little up to 4 weeks, but after that they increased rapidly. According to these results, it is concluded that these feed should be prepared every 4 weeks.

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