The amounts of dimethylamine (DMA) in commercial marine fish and products were determined by employing the steam distillation under two different alkaline conditions, that is sodium hydroxide and magnesium oxide alkali, and the dithiocarbamate method.
The contents of DMA obtained by sodium hydroxide alkaline steam distillation were generally higher than those by magnesium oxide. (see tables 1 and 2). Therefore, the magnesium oxide alkaline steam distillation to isolate DMA from samples is recommendable.

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For the purpose of finding a method for optimization of removal effect on the residual Bordeaux from tomato, an investigation has been made by use of tomato sprayed with Bordeaux in a laboratory.
It was found that the combined use of sugar fatty acid ester and potassium pyrophosphate exhibited good detergency to remove the residual Bordeaux on tomato.
Using this combined detergent, it was also recognized that almost complete removal of the residual Bordeaux was achieved through the following conditions: more than 0.2% of detergent concentration, over 2 minutes washing, above 25°C as washing temperature, and stirring of washing solutions with above 50r.p.m.

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The residue level of hexachlorobenzene (HCB) was surveyed in Japanese food using gas chromatography equipped with an electron capture detector. Analytical method was developed on the selection of column packings and clean-up procedure of crude extract of food sample. Analytical result showed that HCB contaminated almost all food samples but its level was fairly low compared with the reported levels in several foreign countries. Possible source of contamination was discussed.

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Remarkable amounts of nitrite were formed in the juice of komatsuna, rape “Komatsuna”, after incubation at 30°C for 24hr. When the mixtures composed of the above incubated komatsuna juice, marine products and simulated gastric juice were incubated at 37°C for 1hr, 5.6-25.9μg of dimethylnitrosamine (DMNA) was formed. Furthermore, 0.12-0.53μg of DMNA was detected in the stomach contents of guinea-pigs which were administered with the incubated komatsuna juice and salted guts of cuttlefish, “ika-shiokara”. In the control groups of the animal experiment, which were administered with incubated komatsuna juice and water, ika-shiokara and water, or fresh komatsuna juice and ikashiokara, DMNA was not detected.

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A improved method for determination of nitrite in foods was established. Sample was finely comminuted and thoroughly mixed, then 5-10g of the mixture was transferred into a 500ml volumetric flask and added 300ml of distilled water and heated to 80°C on a steam bath for 2hr with occasional shaking. The flask was cooled to room temperature and the volume was made to 500ml with distilled water. After the solution was shaken, it was filtered. Then, 200ml of the filtrate was transferred to a column of Dowex I-X4 (Cl form) of 8cm length. The nitrite on the column was eluted with 25ml of 25% sodium chloride solution. The effluent was adjusted to pH 1.5, and transferred to 50ml Erlenmyer flask, and added 0.5ml of 0.2% o-phenylenediamine solution. After the mixture was stirred for 10 seconds, it was heated to 80°C on a steam bath for 5min. The flask was cooled to room temperature, the reaction mixture was transferred to a 50ml beaker, and adjusted to pH 2.5 with 2% sodium hydroxide solution. The prepared solution was transferred to a 50ml separatory funnel, and added 5g of sodium chloride and 10ml of butyl acetate. Then, 1H-benzotriazol was extracted with butyl acetate and nitrite was determined by gas chromatography as 1H-benzotriazol.
Under the condition described above, it was found that the nitrite in a few kind of foods could be determined with recovery of 97-103% and variation coefficient of about 9%.

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According to the modified methods of Vos and Poter et al., polychlorodibenzofurans (PCDFs) were separated and cleaned-up from commercial PCBs (Aroclor, Phenoclor and Clophen) which had been used in large quantities in the world. PCDFs were identified by gas chromatography-mass spectrometry and quantified by gas chromatography. PCDFs were found in all samples and the results were as follows.
Aroclor: Tri to heptachlorodibenzofurans were found, and the total PCDF concentrations were 2-9ppm.
Phenoclor: Tri to heptachlorodibenzofurans were found, and the total PCDF concentrations were 8-13ppm.
Clophen: Di to hexaclorodibenzofurans were found, and the total PCDF concentrations were 5-17ppm.

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Rate of accumulation of mercury in the different tissues of marine fish species was followed by setting two series of rearing experiments using sea bream (Chrysophrys major) and horse mackerel (Trachurus japonicus). In the first series, fish were fed with ground flesh of horse mackerel in the sea water added by mercuric chloride at the levels of 0.1ppm, 0.01ppm, and 0.001ppm. In the second one, fish were fed with pellets prepared from a variety of deep sea serranids (Malakichthys griseus) which accidentally gave a high concentration of methyl mercury; 1.4ppm. Both groups consisting 75 fish were held in aquaria with capacity of 3 tons of sea water for 91 days. In another series of experiment, the same number of fish were also fed by methyl mercury-containing pellets in the sea water added HgCl₂ at level of 0.1ppm.
In the first group of fish, mercury mostly accumulated in spleen, followed by brain, liver and muscle in the order of concentration. At the end of rearing period, mercury level of muscle was 0.3ppm and 3.0ppm, when they were held in sea water containing mercuric chloride of 0.01ppm and 0.1ppm, respectively. Almost negligible level of mercury in organic form was noticed in these tissues of fish after 13 weeks and this may suggest methylation of mercury hardly occur in these organs.
By oral intake of the pellets, mercury levels were much lower than those of branchial invasion. A level of 0.8ppm in the muscle and brain and 1.2ppm in the liver and spleen was detected respectively after 13 weeks of rearing. Mercury concentration in spleen was not so remarkable after oral feeding of methyl mercury.

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The inhibitory effects of different coal tar dyes, most of which are used for food additives at present time, on pancreatic lipase were examined in vitro by the titration method using a pH stat.
Xanthene dyes except acid red showed the significant inhibition of lipase activity in order of eosine, erythrosine, phloxine and rose bengale. The inhibition was gradually enhanced during preincubation of dye with enzyme or substrate, almost independent of pH in preincubation. On the other hand, other dyes tested did not inhibit the enzyme activity at neutral pH, but most of them showed remarkable inhibition at pH 2.
The inhibitory effect of rose bengale was considerably enhanced by exposure of preincubation mixture under a fluorescent lamp, suggesting a photo-inactivation of the enzyme by halogen atom in the excited molecule of dye.
The inhibition was also influenced by the co-exsistence of other substances such as protein, sodium chloride and sucrose. From the kinetic study, the type of inhibition of pancreatic lipase by rose bengale was non-competitive.

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A method of quantitative determination of minute amount of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), complex mixtures of isomers, was described. PCDD and PCDF (1-10μg) were exhaustively chlorinated to octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) by heating with perchlorinating agent at 68-69°C for 2 hours. The perchlorinated compounds were quantitated by gas chromatography equipped with an electron capture detector using XE-60 as a liquid phase. Yields of perchlorinated compounds from dibenzo-p-dioxin and dibenzofuran both having two or more chlorine atoms were more than 75%, while from those having no or one chlorine were 4-16%. This method was also applicable to quantitation of polychlorinated biphenyls.
By this perchlorination method, the contents of PCDD and PCDF in pesticide PCP, Kanechlor (KC) and Yusho oil were determined. From two brands of PCP, 430 and 0.6μg/g of OCDD and 290 and 1.3μg/g of OCDF were quantitated, respectively. Only PCDF were detected in KC-300, KC-400, KC-500, KC-600 and Yusho oil (3 samples), and their estimated contents calculated from the amounts of OCDF produced were 1.5, 16.6, 2.5, 2.7 and 4.9μg/g, respectively.

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Recently, remarkable progress has been made on the sanitary control of the milk plant, especially in the countermeasure against air microbes, by introducing such equipment as an air-conditioner. Then a survey was conducted to analyze the effect of such progress upon the aspect of bacterial contamination of bottled milk and the environment of the plant. Since a similar survey was carried out in 1964 before such progress was made, the present survey was performed almost under the same conditions as it in 1974. After that, results were compared between the two surveys with the following findings.
1) When bottled milk was examined for bacterial contamination, psychrotrophic, mesophilic, or coliform bacteria were not detected from it immediately after bottling. When bottled milk was stored at 37°C for 24 hours or at 6°C for 7 days, the number of its samples showing a bacterial count exceeding 50, 000, or the lowest allowable limit, was much lower in the present survey than in the 1964 survey. The frequency of appearance of milk samples which failed to meet the minimum requirements after storage was higher in summer than in winter.
2) When bottled milk samples were stored at 37°C in the winter of 1964, their bacterial flora contained various types of thermolabile bacteria simultaneously with Bacillus organisms. When the same samples were stored at 37°C in the winter of 1974, their bacterial flora was composed exclusively of Bacillus organisms, which were presumed to have withstood pasteurization and disinfection. When the same samples were stored at 37°C in the summer of 1974, their bacterial flora contained thermolabile bacteria in addition to Bacillus organisms.
3) The count of falling bacteria and the bacterial count of finished products (after storage) were compared between the line with an air-conditioner introduced and that without such equipment introduced in the same plant conducting UHT pasteurization. As a result, much more satisfactory results were obtained from the former line.

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In order to establish a rapid and accurate method for the quantitative test for gas of baking powders, this research was undertaken. Three methods were subjected to comparison; i. e. contemporary official method of Japan (volumetric method) in which the gas produced in hot water was measured directly, an improved volumetric method proposed by the authors and absorption-titration method used in the alkali manufacture.
In the improved volumetric method a trial manufacture prepared after the performance of several improvements on Chittick's apparatus shown in the Official Methods of Analysis of AOAC was used. The volume of gas produced at 75°C under the addition of hydrochloric acid was expressed at the normal state.
The principle of the absorption-titration method is as follows: The method consists of boiling sample with acid in an evolution flask, expelling the evolved carbon dioxide completely into the absorption apparatus containing solution of sodium hydroxide and barium chloride and, after shaking the apparatus vigorously, back titration of the residual hydroxide was carried out with standard acid solution under the atmosphere free from carbon dioxide., AGK-type apparatus was used.
Satisfactory results were obtained on sodium bicarbonate standard by use of the modified volumetric method and absorption-titration method, the recoveries of carbon dioxide being around 100% and coefficients of variation being within 3%. Contrary to this, it was impossible to produce gas from sodium bicarbonate by the contemporary official method. The addition of alum, calcium phosphate or tartaric acid allowed the production of gas, the gas volume measured, however, varied from one to another.
From the comparative experiments of single-type baking powders (three commercial products were used) it was confirmed that no significant differences were observed between the values obtained by both improved volumetric method and absorption-titration method, the reproducibilities being satisfactory. The contemporary official method was apt to give too low gas volumes.
The adoption of the modified volumetric method seems to be advantageous since the time necessary for measurement of one sample (including blank test) is only 15 minutes, a quarter compared with the absorption-titration method. In Japan the gas evolved from 2g of baking powder must not be less than 70ml.

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For the determination of heavy metals in edible oil with atomic absorption method, an effective technique with a low tempereture asher using the oxygen plasma have not been established.
When some oils were tried to be ashed, they were easily polymerized to become resin form, and ashing time need for a month.
In order to reduce the ashing time, some additives which serve as intermediate to enlarge oil surface and as catalyst for oxidation were examined.
In the case of addition of agar or cornstarch to oil, oil became spongy form and ashing was completed within about 48hr.
But agar was not suitable for the analytical purpose with the atomic absorption method on account of the presence of heavy metals contaminant.
Therefore cornstarch was most suitable ashing agent, when food oil was ashed with a plasma system.

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[in Japanese]

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