Methyl linoleate hydroperoxide (ML-HPO) was separated from methyl linoleate autoxidized at about 10°C by the combination method of simple countercurrent extraction and column chromatography. The peroxide value of ML-HPO was more than 5, 780meq/kg. This value indicated that the material was essential pure monoperoxide. ML-HPO had a conjugated diene and a hydroperoxide group. Being hydrogenated with platinum oxide, ML-HPO absorbed 3.11 mole of hydrogen, and was converted into a mixture of great quantity of hydroxystearic acid methyl esters and slight unknown material. The methyl esters contained equal amount of 9 and 13 hydroxystearic acid methyl esters. When ML-HPO stored in air and in nitrogen at 25°C, the contents of conjugated diene and peroxide value of ML-HPO decreased respectively. This fact evidences that decomposition of ML-HPO occurred in those atmospheric conditions. Methyl 8-formyloctanoate (MFO) was detected in oxidized ML-HPO, was not detected in the substance that decomposed under nitrogen, by gasliquid chromatographic analysis. ML-HPO and hydroxyoctadecadienoic acid methyl ester (HODE) which was obtained from reduction of ML-HPO with stannous chloride absorbed about 1 mole of oxygen at 45°C, respectively. In the oxidation process, the contents of peroxide value and conjugated diene of ML-HPO decreased proportionately with oxygen uptake. MFO and malonaldehyde were found in oxidized ML-HPO. One mole of oxidized ML-HPO released 0.393 mole of MFO at maximal rate. The quantity of malonaldehyde found was about one-tenth of MFO. MFO and malonaldehyde were found in case of HODE as well as ML-HPO. Thier quantity, however were less than in case of ML-HPO. The above results indicated that MFO was not formed from ML-HPO that was the first product of autoxidation of methyl linoleate, but formed from furthermore oxidized ML-HPO.
Sulfur dioxide in dried Cortinellus Shiitakewas detected by the method of starch potassium iodate paper and malachite green's reactions. But sulfur dioxide was not detected in natural Cortinellus Shiitake. The amount of sulfur dioxide determined by Monnier-Williams's method was 0.01-0.13g/kg in dried Cortinellus Shiitake. When dried Cortinellus Shiitake was wetted in water, the amount of sulfur dioxide increased during four hours. After wetting six hours later, sulfur dioxide level became constant. The amount was not influenced by drying method, drying time, nor by the place of production and the kind of Cortinellus Shiitake. When lenthionine was added to dried Cortinellus Shiitake, increase of the amount of sulfur dioxide was not observed. In view of these facts, it was supposed that, when dried Cortinellus Shiitake was wetted in water and was boiled with 25% phosphoric acid, sulfur compounds of Cortinellus Shiitake are decomposed to produce a substance which is positive to the sulfur dioxide reaction.
The color reaction of Jonescu, based on the reaction of salicylic acid with ferric chloride, was investigated for the quantitative determination of benzoic acid in margarine, and the appropriate hydrogen peroxide concentration, the reaction temperature and time on heating and ferric chloride concentration were decided. The proposed method, when applied to the sample of margarine to which a known quantity of benzoic acid had been added, showed a recovery of about 93%. It was confirmed that the proposed method was less affected with impurities contained in the sample than the alkali titration method and the ultraviolet absorption method, and was found to be suitable for the purpose of routine work.