POSTHARVEST STIMULATION OF SKIN COLOR IN ROYAL-GALA APPLE

The red color of Royal Gala apple(Malus domestica Borkh.) skin increas ed in intensity following irradiation with ultraviolet (UV) and white light. The enhanced red apple color was due to an increase in anthocya nin concentration and the increase was dose dependent. High-performanc e liquid chromatography analysis showed that the composition of flavon oids in UV treated rind natural red colored apple skins was similar. T he red apple skin color further increased after storage at 4C in the d ark During the course of irradiation the enzymatic activities Of pheny lalanine ammonia lyase (PAL) and chalcone isomerase (CHI) increased 10 - to 20-fold. Northern analysis showed an increase in PAL transcripts during the irradiation treatment, suggesting that the increase in PAL enzymatic activity was due to de novo synthesis of the enzyme in apple skin cells.