Akio Tanimura

Hygienic Studies on Monascus Pigments (II)

The mold Monascus is used for brewing of red rice wine (an-tyiiu) and the production of monascus pigments which is added to foodstuff as a natural food dye.In the present paper, the fundamental methods for fractionation and quantitative analysis of monascus pigments were described.The principle for the fractionation of monascus pigments is as follows: a mixture of purple, orange and yellow pigments was applied to a silica gel column. Purple pigments were adsorbed on the column with ether, but orange and yellow pigments were eluted with ether. The purple pigmetns remained on the column were eluted with methanol. Ether saturated with ammonia was added to the eluate which contains a mixture of orange and yellow pigments. Orange pigments in the mixture were converted to purple pigments by the reaction with ammonia in ether. Then the mixture was applied again to the silica gel column. Yellow pigments were eluted with ether, and orange pigments, which have been converted to purple pigments, were eluted with methanol.For the determination of monascin, test solution was heated at 100°C for 10min with concentrated sulfuric acid and produced fluorescence was determined at 453nm for excitation and 507nm for emission.The above method was applied to red rice wine, and 9.0-11.1ppm of water-soluble pigments, 2.2-3.1ppm of purple pigments, and 0.9-1.9ppm of yellow pigments were determined. Orange pigments were not detected in red rice wine.

Microanalysis of Brominated Oil in Soft Drinks

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%.