In winter, a large amount of white substance precipitated on the bottom of fermented sauce storage tank. The nature of the precipitate, and methods for preventing sediment were studied. The white substance was collected by filtration, washed with cold water and air-dried. It was positive in xanthoprotein and Folin reactions. Its Rf value on thin-layer chromatogram and infrared spectrum agreed with those of reagent tyrosine. Fermented sauce which generated white sediment contained larger amount

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... f tyrosine than that giving no sediment. It was considered on the basis of these results that tyrosine was precipitated owing to large tyrosine content of fermented sauce and poor solubility of tyrosine at low tempearture. The fermented sauce treated with active carbon became easier to precipitate tyrosine. The reason was considered that amino acids, which increased the solubulity of tyrosine, were removed by active carbon. The addition of small amount of glucose followed by heating resulted the promotion of Maillard reaction, and decrease in tyrosine content, and thus prevented the sedimentation of tyrosine in fermented sauce.