Rind Color Development in Satsuma Mandarin Fruits Treated by Low-intensity Red Light-emitting Diode (LED) Irradiation

Here, we investigated the effect of irradiation by a low-intensity red light-emitting diode (LED) (photon flux 12 µmol•m−2•s−1) on rind color development in Satsuma mandarins after harvesting at two different periods. In the early harvest fruit, the a* value for Satsuma mandarin peel treated by red LED irradiation was 2.7 and 2.4 times higher than that for the dark treatment fruit at 4 and 8 days irradiation, respectively. In the commercial harvest fruit, the a* value of the peel treated by red LED irradiation was 1.2 and 1.4 times higher than for dark treatment at 4 and 8 days irradiation, respectively. Additionally, we examined the influence of red LED irradiation on the internal fruit quality of Satsuma mandarins from the two harvest periods. Low-intensity red LED irradiation did not affect fruit quality. We elucidated the effect of intermittent red LED irradiation on the change in a* value of mandarin fruits. These results indicated that treatment with low-intensity red LED irradiation is sufficient to develop a degree of rind color in mandarins without affecting the internal fruit quality.