Effect of red light irradiation on skin coloration and carotenoid composition of stored ''Miyauchi'' iyo (Citrus iyo hort. ex Tanaka) tangor fruit

Effect of red light irradiation on skin color development and carotenoid composition of stylar end of Miyauchi iyo (citrus iyo hort. ex Tanaka) tangor fruit was examined during storage. Both increase in a and a/b value and decrease in b value were enhanced by the irradiation. The a/b values of the fruit exposed were higher than those of control during the whole storage period. HPLC analyses also revealed the increase in total carotenoids content, of which the carotenoids that were tentatively named B and F most greatly accumulated. Similar tendencies were observed at equator and stem end portions. These results indicate that red light irradiation is involved in not only acceleration of overall color development but also enhancement of red color pigmentation by influencing a certain specific pathway of carotenoid biosynthesis