A study* from the University of Ljubljana (Slovenia) showed how light wavelengths can influence the quality of cherries in cold storage. Irradiation with blue light increased anthocyanin content, while blue and white-blue-green light increased phenylalanine ammonia lyase (PAL) activity. Researchers have in fact found a high correlation between PAL and anthocyanins. 

"Light can influence the post-harvest formation of bioactive compounds in fruit and vegetables. The objectives of this study were to determine the physico-chemical changes and PAL and flavonoid 3'-hydroxylase activities in cherries irradiated with light-emitting diodes."  

Cherries were stored under UV-B and blue light and under a combination of white, blue and green light for ten days.

"Irradiation with blue light significantly increased the anthocyanin content (cyanidin 3-O-glucoside, cyanidin 3-O rutinoside) content and significantly influenced the color parameters of the fruit. The combined white-blue-green light produced similar yet less pronounced effects, while UV-B light produced similar effects to control (in the dark).

"Blue and white-blue-green light increased phenylalanine ammonia lyase activity.

"Irradiation had no significant effects on ascorbic acid and phenolic profile. Highly-significant correlations were found between anthocyanins and PAL on the one side and with fruit color on the other."

*Doris Kokalj, Emil Zlatić, Blaž Cigić, Rajko Vidrih, 'Postharvest light-emitting diode irradiation of sweet cherries (Prunus avium L.) promotes accumulation of anthocyanins', 2019, Postharvest Biology and Technology, Vol. 148, pag. 192-199.