The History of Mucuna Beans and Color Characteristic

Abstract

  We investigated the history of Mucuna beans described in the old documents: “Shinkan tashikihen,” “Honchoshokkan,” “Yamato honzou,” “Honzou koumoku Keimoou kanno niju,” and “Wakan sansaizue” that were published in the Edo period. Focusing on the cooking method “removal of black juice” explained in “Wakan sansaizue,” various browning reactions during the cooking of Mucuna beans were examined. A fast reaction was observed on the cut surface of immature Mucuna beans due to the simultaneous presence of polyphenol, polyphenol oxidase and oxygen. In the case of matured Mucuna beans soaked in warm water, the browning was milder than when exposed to air; this is presumed to be due to the influence of the amount of oxygen dissolved in water, the soaking temperature, the substance to be eluted, and the optimum temperature of the enzyme contained in the Mucuna beans. It was suggested that the amount of L-DOPA decreased when the color of soaking water and/or the soaked beans became darker. However, these browning reactions did not require the whole amount of L-DOPA contained in the Mucuna beans; they were darkened by a relatively small amount of L-DOPA.