米麹の褐変に関する研究 : (第5報)褐変色色素前駆物質L-ドーパの酵素的生成

概要

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Most rice-koji for sake-brewing is white, but some, from certain strains of Aspergillus oryzae, turn brown during storage in the air. This browning is sometimes accelerated by wet conditions. Previously, the authors have reported the extraction and identification of L-dopa as a precursor of pigment in browned rice-koji.This paper described the formation of L-dopa from L-tyrosine by an enzyme obtained from rice-koji prepared by a certain strain of A. oryzae which always produces brown koji. The enzymatic oxidation of L-dopa was studied spectrophotometrically. The reaction proceeded in three chromophoric phases : the first phase was the formation of red pigment; the second, an intermediate purple pigment; and the third, melanin formation. From these results, it was concluded that this enzyme is responsible for the browning of rice-koji.
社団法人日本生物工学会の論文
1972-07-25