Inactivation of trypsin in the presence of xanthene dyes was observed through the irradiation of visible ray, but not observed in the dark. As the substrate for trypsin, rose bengale-bound casein was only 80% effective as compared with untreated casein.
The inactivation under the visible ray was accelerated by the elimination of the air, and was prevented in the atmosphere of oxygen. It was assumed that those xanthene dyes inhibitde the trypsin activity via triplet energy transfer. Since the presence of oxygen was essential for the photo-degradation of tryptophan and histidine by rose bengale, it was suggested that photo-inactivation of trypsin was induced without degradation of amino acid residue in the trypsin molecule.

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キサンテン系食用色素によるトリプシンの光不活性化の機構を色素分子中のハロゲン原子に注目して実験を行ない, 光化学反応によって解裂したハロゲンが本酵素の失活に関与することを推定した.

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In the qualitative tests of coal-tar dyes in foods, woollen yarn are used for the clean up of dyes. However, dyes such as phloxine or rose bengale are strongly adsorbed and considerable amount of the dye remains in the wool fibre. Since wool consists of keratin, denaturation of protein occurs by heating with urea in water, which might result in the better extraction of the dye from the fibre. Under such a hypothesis, the presented experiments were made.
Nineteen kinds of tar dyes were tested with urea treated woollen yarn. The recoveries of these dyes increased 1-4 times with untreated woollen yarn and about 32% up in average for yarn activated by ammonia. Further, when the permitted artificial food dyes in Japan were concerned, they were adsorbed on urea-treated woollen yarn and then eluted by a saturated solution of ammonia alkaline urea, the recovery rate rose to 82.9-98.8%. A way was thus settled for a quantitative estimation of coal-tar dyes by use of woollen yarn.

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When Streptococcus faecalis cells were subjected to freezing (-20°C) and storage (1 month), 29 to 44% of the viable population was unable to reproduce on the selective media (SF medium, KF medium and buffered azide glucose glycerol agar). Freeze-drying of the test organisms suspended in distilled water produced the same type of sublethal injury. These injured cells were found to be sensitive to 0.05% NaN₃ in the selective media. A parallelism was observed between the extent of NaN₃-sensitive injury and that of the metabolic injury (peptide requirement) resulted from freezing or freeze-drying. The recovery of colony-forming ability of the injured cells was influenced considerably both by the type of peptone used and its concentration in selective media which contained 0.05% NaN₃. It was confirmed that normal NaN₃-resistance of the test organisms was easily restored after the incubation of the injured cells at 37°C for 1 hour in tryptone yeast extract glucose broth containing chloramphenicol (30μg/ml). In the detection of S. faecalis in frozen or freeze-dried foods, it would be very important to recognize the limitation of selective medium and to adopt a suitable condition of the cultivation which can accelerate the repair in injured cells.

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Nitrite, one of the precursors of dimethylnitrosamine, distributes widely in natural foods and also used as a color fixative in meat products. In this paper, nitrite contents in vegetables, fruits, pickles, cereals, potato, juice, cheese, ham, sausage, canned fish, products, dried small sardine, salmon roe and pollack roe were determined. In vegetables and meat one peak of nitrite content was observed in the period of storage and about 100ppm of nitrite was found in the juice of pickles.
In 10 samples of meat products, nitrite contents were under the limit restricted in the Food Hygienic Law of Japan except one sample.

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A method for the determination of 3, 4-benzopyrene in Japanese teas has been developed. Japanese teas were extracted and saponified with alkaline methanol in Soxhlet extraction apparatus. The extracts were partitioned with n-hexane, dimethyl-sulfoxide, and n-hexane successively, and these partitions were condenced. After 3, 4-benzopyrene was isolated by alumina column chromatography, measured by spectrophotofluorometry and calculated from the wave length of 405mμ by the “baseline” method. Identification of the hydrocarbon was made by thin layer chromatography.
The recoveries of 3, 4-benzopyrene added to each 100g of Japanese teas at a level of 20ppb were ranged from 65 to 86%. However, when Japanese teas were extracted with hot water instead of alkaline methanol, the results were reduced to 0 to 3%. This fact seems to indicate that infusing tea in hot water is safe relating to carcinogen 3, 4-benzopyrene.
3, 4-benzopyrene was found from Japanese teas at levels varying from 0.0 to 16.0ppb.

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Steam distillation and extractions with several kinds of solvents were investigated as the separating method of dibutylhydroxytoluene (BHT) and butylhydroxyanisole (BHA) from fatty foods. The results obtained are as follows.
1. The method of steam distillation is available only for lower fatty foods.
2. n-Hexane-acetonitrile system extraction is recommended for practical use for high fatty foods.
3. For the concentration of solvent containing BHT or BHA, Kuderna-Danish concentrator is available.
4. BHT and BHA are separated easily from each other by alumina column.

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Colorimetric determinations of dibutylhydroxytoluene (BHT) with α, α'-dipyridyl-ferric chloride and butylhydroxyanisole (BHA) with 2, 6-dichloroquinonechlorimide (Gibbs reagent) were studied.
The concentration of ethanol in prepared solution was most suitable at 30 percent for BHT, it was 50 percent concerning with BHA and the calibration curves of them were liniar within the range of 10-50μg in prepared solution taken.
The colorimetric method of BHA is available for the determination of BHA in food which contains both BHA and BHT, but it is impossible to determine BHT in the food containing both BHA and BHT by the colorimetric method of BHT.
Therefore, in the case where one sample contains both BHT and BHA together, it is necessary to separate BHT and BHA from each other.

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The fundamental methods of separation and colorimetric determination for dibutlylhy-droxytoluene (BHT) and butylhydroxyanisole (BHA) in foods were described in the previous papers.
In this paper, we applied these methods to the commercial foods, and determined the amounts of BHA and BHT in foods and found that these methods were available for the determinations of them in the commercial foods, and the values of colorimetric determination agreed with the values of gaschromatographic determination.
From our results, the amounts of BHA or BHT contained in foods were found to be lower than the limits that were specified in the Food Sanitation Law of Japan. The decreasing rate of BHT in chewing-gum by chewing showed about 50% after 30 minutes.

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農薬散布歴の明らかな農場栽培のコマツナ (最終散布農薬: ヒ酸鉛, BHC) を洗剤洗いと水洗いにより, ヒ素, 鉛, およびBHCの除去性を検討した.
1) 試料の付着農薬量の個体差による影響をさけるため, 洗浄液に溶出した農薬量と処理試料中の残存量の和を洗浄前付着量として, 除去性を評価し, この方法が有効であることを認めた.
2) ヒ素, 鉛は共に水洗いを繰り返すことによって, 80%以上の除去率を得たが, 洗剤洗いでは, より早く効果的に十分な除去性を得ることができた. これは, 洗剤が葉の粗面効果を小さくし, 農薬の洗浄除去をより容易にするためと考える.
3) BHCは水洗いではほとんど除去されないが, 洗剤洗いでは約2.5倍以上の除去率が得られた. また, すすぎの効果は洗剤洗いの場合大きく認められた. BHC除去性が困難なのは, 葉のワックスへの浸透によるためと考える.

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サントウサイ, キュウリ, トマト, キャベツについて, 残留農薬 (ヒ酸鉛, スミチオン, エルサン, マラチオン, DDVP) の除去性を, 振り洗い, ブラシ洗いおよび浸漬洗いという機械力の加え方の異なった各種の洗浄方法によって検討した.
1) ヒ酸鉛は水だけでも繰り返し洗うことにより, かなりの除去率が得られるが, 洗剤, 機械力を加えることにより, より能率よく高い除去性が得られた.
2) 有機系農薬では, 機械力の加わり方の大きい洗浄方法ほど高い除去性が得られ, 洗剤使用の効果は機械力の強いほど顕著に認められた.
3) サントウサイと形態の異なるキュウリ, トマト, キャベツについての検討では, 流水すすぎの効果が大きく, 野菜の形態による除去性に差のあることを認めた.

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The analysis of brominated oil in soft drinks was studied. Brominated oil was extracted with hexane, the extract was concentrated to about 1ml and decomposed by oxygen flask combustion method, bromine liberated was absorbed into 10ml of 0.1N sodium hydroxide solution. After the solution was neutralized with 1N acetic acid, 3ml of the solution was placed in a small porcelain dish, 1ml of 0.01% fluorescein in 0.1N sodium hydroxide solution and 1ml of 5% peracetic acid solution prepared with acetic acid and 30% hydrogen peroxide were added, and evaporated to dryness on a water bath, the red color appeared on the residue which was due to eosin produced from bromine and fluorescein. The limit of detection was 4μg of bromine in 3ml of the neutralized solution.
Sodium chloride and potassium iodide were tested by the presented method, and chloride was not colored, on the other hand a red color appeared with iodide, however, it seemed that the analysis was not interfered with iodide, because iodides were not contai ned in soft drinks and the reagents used for the tests.
Bromine in the prepared solution was determined as follows. One milliliter of the prepared solution was heated in a water bath for two hours after mixed with 1ml of fluorescein solution and 1ml of 5% peracetic acid solution. After cooling, 2ml of 10% ammonia water was added to the mixture and filled up to 20ml with water, the absorbance of the solution was measured at 517mμ of wavelength. The recovery of brominated oil in soft drinks was 94-95%.

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The methods for the determination of diphenyl in citrus fruits were studied. Diphenyl was separated by distillation and dissolved in cyclohexane, by this method about 77% of diphenyl added was recvered after distillation for 5 in minutes and over 99% was recovered in an hour.
For the U. V. spectrophotometry, the cyclohexane solution was cleaned up by thin layer chromatography (TLC) using silica gel plate containing fluorescent indicator. TLC spot was extracted with cyclohexane and measured spectrophotometrically at 248mμ. Recovery of the added diphenyl by this method ranged 91 to 96%.
In the gaschromatographic determination the peak of diphenyl was separated from other peaks of essential oils in citrus fruits with polyethylene glycol, and diphenyl was determined by internal standard method using 2, 3-dimethylnaphthalene. Recoveries of diphenyl in fruits by gaschromatography were 91 to 96%. The amounts of diphenyl in orange did not decrease. The change of residual diphenyl in orange with time was investi gated, as the resultant diphenyl was stable at least for 25 days, it was assumed from the result that diphenyl dissolved into essential oil in the fruit.

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In the previous paper, the authors reported on the thin layer chromatographic technique for the separation of inorganotin and organotin compounds.
In the present paper, a rapid and simple procedure was contrived for the identification of the tin compounds in foods by the thin layer chromatography.
The tin compounds added to foods were easily extracted with diethyl ether from the samples acidified with hydrochloric acid as they were or as their thiocyanates.
In the extraction procedure, the ether containd in the mixture of emulsion and suspension, which had been formed through vigorous shaking with each sample, was successfully separated by centrifugation using filter paper and the perforated disc made of “teflon”.
After the extracts were evaporated to dryness, inorganotin and organotin compounds in the residues were identified on thin layer chromatography.

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緑茶または紅茶を基質とし, 酵母および酢酸菌からなる「種」をうえつけて製する酸味をおび表面に凝塊をつくる保健飲料が, わが国をはじめ台湾, ソビエトなどの諸地域でつくられている. 今後類似の飲料の発展の可能性もあり, 食品衛生学上重要と考えその微生物学的な研究をおこなった. すなわちこれらの試料について分離同定を行なうと同時に, 凝塊をつくる微生物および生成される酸について検討した.
1. 本邦産の茶煎液からは細菌としてAcetobacterxytinum, 酵母としてSaccharomyces sp., TorulopsisfamataおよびPichia membranaefaciensを分離同定し, その主要な酵母はSaccharomyces sp. であった.
2. 台湾試料からは, 輸送中に死滅したのかAceto-bacterは分離し得なかったが, 一応試料の凝塊は本邦産と同様のものであった. また酵母としてCandida gui-lliermondii, C. obtusa, Kloeckera apiculataが分離されたが, そのほとんどはCandidaであった.
3. 凝塊をつくる微生物はAcetobacter xylinumであった. また試料中の酸はPPCの結果, 酢酸であった.
4. 分離株を用いて, 再現試験を行なった結果は, 試料と同一の形状と味覚をもつ飲料をうることができた.

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The concentration of tin in foods sufficient to cause poisoning is from 50 to 100ppm, rather higher as compared with those of other metals. So, the present study was attempted to develop a simple method for not the determination of the tin in low concentrations but the determination of the metal within a concentration of 50 to 100ppm and over by Atomic Absorption Spectrophotometry, utilizing a slot burner and acetylene-air flame.
For the purpose of comparison, colorimetric determination was also carried out using salicylidenamino-2-thiophenol, as had been recently reported by Gregory.
The foods tested (canned fish, corned beef and fruit juice) were ashed either by dry ashing in an electric furnace or in a low-temperature dry ashing device, extracted with hydrochloric acid and them estimated directly at 2863Å.
The recovery rate of tin by the dry ashing was 92 to 103%, while that by the low temperature ashing was less than 50%. In the latter case, extraction with alkaline eleratet the recovery to as high as 90%. The recovery rate by the colorimetric method was 80 to 91%.
In the Atomic Absorption Spectrophotometry, the effects of various coexistent substances were less apparent when acetylene-air flame was used instead of hydrogen-air flame.

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ミルクチョコレート中の乳脂肪分の測定法について検討した.
1. 脂肪の抽出法としては塩酸加熱分解法および直接抽出法について比較した結果, ブラックチョコレートにおいては両者の間に差は認められなかったが, ミルクチョコレートでは直接抽出法は塩酸加熱分解法に比較して最高4.66%も低い脂肪含量を示すことを認めた. これは抽出の際, 乳タンパク質による皮膜を破壊する必要のあることを示すものである. 塩酸加熱分解法のうちS. B. R. 法とA. O. A. C. 法について比較した場合, 前者の方が簡便であり, しかも高い値の得られることを認めた.
2. ココアバター, やし油およびパーム核油のライヘルトマイスル価はそれぞれ0.2. 6.4, 4.3, 酪酸価はそれぞれ0, 0.6, 0.2であることを認め, 総脂肪中の乳脂肪分の算定式として
[{ライヘルトマイスル価 (チョコレート) -0.2} /28.1] ×100および [酪酸価 (チョコレート) /20] ×100
を提出した. 両者について市販ミルクチョコレートを試料として比較した結果, ライヘルトマイスル価の式による計算値にやや高い値を示すものが認められた.
3. 試作ミルクチョコレートの総脂肪中の乳脂肪分は原料配合比より算定した結果では17.9%, 分析値からの算定値はライヘルトマイスル価では19.2%であったが酪酸価では17.9%であって原料よりの値とよく一致した.
4. 市販ミルクチョコレート6種の乳脂肪分を酪酸価法によって測定した結果3.3～8.4%の範囲にあることを認めた.

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