Limonoid Glucosides Contents of Several Citrus Fruits in Japan and the Influence of Canopy Depth during Fruit Development on them

Abstract

Limonoid glucosides contents of eight commercially grown citrus cultivars including Satsuma mandarin, Hassaku, Iyo, Kiyomi tangor, Natsudaidai, Siranuhi, Sweet Spring tangelo and Sanbokan were analyzed. Influence of canopy depth during fruit development on limonin 17-β-D-glucopyranoside (LG) contents of Satsuma mandarin was also investigated. Total limonoid glucosides concentrations of analyzed fruit ranged from 70 to 260 ppm and Iyo, Sweet spring tangelo and Kiyomi tangor contained relatively high concentration of limonoid glucosides. LG ratio for total limonoid glucosides was lower in Sweet Spring tangelo, Kiyomi tangor, Nastudaidai, Siranuhi and Sanbokan than in previously reported major citrus cultivars which contained LG predominantly. With early ripening cultivar of Satsuma mandarin, LG started to be synthesized at the middle of August. The LG concentration was gradually increased until the harvest season and reached around 100 ppm in November. The LG content of the fruit picked from exterior canopy was constantly higher than those from interior canopy during the fruit development. This suggests that the differences in light intensity due to the different canopy positions affects the LG contents of the fruit. Fruit with higher LG content could be produced by increasing the light intensity during the fruit development.