When yeast cells suspended for ten minutes in a solution containing each of four kinds of cationic detergents at a concentration of 0.25mM respectively were washed 3 times with water, 11% to 83% of the adsorbed detergents were removed. However, no significant reversal of the growth-inhibition was observed after such washing, as seen in Fig. 1. On the other hand, effects on the cell of washing with 10-4M anionic detergents such as sodium lauryl sulfate or sodium laurate were presented in Fig. 3. Cells treated with cetyldimethylbenzylammonium chloride (C-Bz) or lauryl-3-chloro-2-hydroxypropylammonium chloride (L-Ep) showed considerable reversal of the growth-inhibition, while the growth of the cells treated with lauryldimethylbenzylammonium chloride (L-Bz) was more strongly inhibited by repeated washing with anionic detergents. As shown in Fig. 4, among the cationic detergents, C-Bz was the most efficient both in the degree and the rapidity of growth-inhibition, and the effectiveness decreased in the order of L-Ep, L-Bz, and cetyl-3-chloro-2-hydroxypropylammonium chloride (C-Ep). However, a relation between the effectiveness of a cationic detergent and the reversal of growth-inhibition by its elution was not clear.
The degradation mode of sorbic acid, dehydroacetic acid, methyl- and propyl-p-hydroxybenzoate in aqueous solution respectively was studied, using gas chromatographic assay method. It was noted that sorbic acid both in acidic and alkaline region was the most stable of these preservatives, whereas dehydroacetic acid was rapidly decomposed either in acidic or in strong alkaline and, hydrolysis of p-hydroxybenzoate was observed in alkaline region. The simultaneous detection of 2, 6-dimethyl-4-pyrone, 2, 6-dimethyl-4-pyrone-3-carboxylic acid, triacetic acid lactone and 2, 6-dihydroxy-2, 5-heptadien-4-one (diacetylacetone) as presumable degradation products of dehydroacetic acid could be readily implemented with direct injection gas chromatography. The degradation mechanisms of dehydroacetic acid and 2, 6-dimethyl-4-pyrone-3-carboxylic acid, both in acidic solution at 60° respectively, were followed by gas chromatography at a given time interval. As degradation products of dehydroacetic acid and 2, 6-dimethyl-4-pyrone-3-carboxylic acid, 2, 6-dihydroxy-2, 5-heptadien-4-one (diacetylacetone) and 2, 6-dimethyl-4-pyrone were identified with direct injection gas chromatography, and 3-carboxy-2, 6-dihydroxy-2, 5-heptadien-4-one was separable newly as the ester. According to the degradation products, the degradation pathway of dehydroacetic acid in acidic solution was considered to be the fact that of the lactone ring dehydroacetic acid was first broken to produce 3-carboxy-2, 6-dihydroxy-2, 5-heptadien-4-one, and then its decarboxylation immediately following the reaction yielded 2, 6-dihydroxy-2, 5-heptadien-4-one, which was dehydrated finally to 2, 6-dimethyl-4-pyrone.
Thirty-six kinds of water-soluble food dyes permitted in Japan, U.S.A., U.K., and West Germany were classified into three groups in accordance with those positions of flow when they were chromatographed on paper with a mixture, as developing solvent, of 6 volumes of aceton, 5 volumes of iso-amylalcohol, and 5 volumes of water, by using Naphthol Yellow S and New Coccine as the standards. Dyes of each group were then divisible according to the homogeneity of color. Samples thus divided were submitted to high-voltage paper electrophoresis in the same manner reported in the previous paper (This Journal, 2, No. 2, 44 (1961)) by use of Sørensen buffer of pH 4, 6, 8, and 10, besides 5N HAcO and 0.1N NaOH as electrolytes. The results obtained were compared with those of paper chromatography with the following three solvent systems. Sol. 1 Butanol·Alcohol·0.5N NH4OH (6: 2: 3) Sol. 2 Butanol·Alcohol·0.5N HAcO (6: 2: 3) Sol. 3 25% Alcohol·5% NH4OH (1: 1) Some similarity was found between paper electrophoresis and non-partition paper chromatography (e. g. Sol. 3), but (in the case of electrophoresis), electrophoretic zones were less diffused and the better separation of dyes having similar chemical structure was attained in general, as compared with that of paper chromatography. A Table attached shows the systematic separation method for all dyes by means of paper electrophoresis and paper chromatography respectively.
Hydrogen peroxide (H2O2) has been used for Japanese noodle for the purpose of bleaching, but in the case of packaged noodle, soaking in H2O2 solution and heating were expected considarable sterilizing effects, too. Repeating the soakness of noodle, the concentration of the H2O2 solution was reduced. Therefore, it was necessary to keep the constant concentration of H2O2 in the solution. A new type of the test paper by which H2O2 concentration was checked, was developed. The white color of the paper in which Ti (SO4) 2 permeated, was changed yellow to orange according to the H2O2 concentration, when it was soaked in H2O2 solution. The effect of other substances against colorization was not observed. The consumption of H2O2 by the treatment of soaking Japanese noodle in the period of process, consisted of one third of decomposition and the rest which was absorbed in noodle. Absorbed H2O2 to noodle was almost easily extracted with water, washing several times. Absorbed quantity of H2O2 was varied by the length of soaking period, H2O2 concentration, ratio of amounts of noodles and H2O2 solution and so on. H2O2 was observed not only the surface absorption but also inner parts of noodle. Permeable velocity of H2O2 into noodle and the decomposed quantity of H2O2 in heating process were to do with the sterilization of it. From the commercial products, just after the production, H2O2 was determined 300-500ppm (in the case of Japanese noodle), and 50-150ppm (spaghetti). This H2O2 decreased gradually, and almost vanished for one to three monthes under the ordinal storage conditions.
Possible metabolites of Disyston were studied by means of thin-layer chromatography, IR spectrum and electron capture gas chromatography. Ten ng of Disyston, 1-2ng of Disyston sulfoxide, 5ng of Disyston sulfone, 500ng of Systox, 5ng of Systox sulfoxide and 100ng of Systox sulfone were detectable on gas chromatograms, utilizing 2% Apiezon L and 1% 1, 4-Butandiolsuccinate as the stationary phase. And actually as the metabolic residues, Disyston sulfoxide and Systox sulfoxide were detected at the very low level in extracts of strawberries and edible roots of lilies.