The effect of postharvest storage temperature on sweet cherry (Prunus avium L.) phenolic metabolism and colour development

- The cold storage of cherries affected both the enzyme activity and transcription of PAL, however, insignificant differences were detected in the concentrations of Total Phenolics.
- The storage temperature appeared to have significantly affected the chromatic attributes of the fruits.
- Cold storage resulted in reduced expression of the genes coding for ANS and UFGT.

Sweet cherry storage at 1 °C significantly affected many biochemical parameters linked to anthocyanin concentration in fruits and subsequently their colour. While no significant differences in the concentration of total phenolics were detected among treatments, total anthocyanin concentration and phenylalanine ammonia-lyase enzyme activity, as well as the transcription of anthocyanidin synthase and flavonol 3-O-glucosyltransferase (genes coding for enzymes fundamental for the anthocyanin synthesis) were considerably lower in fruits stored at 1 °C (with or without a 24-h period of storage at 20 °C) in comparison to the initial fruits at harvest. In contrast, the fruits stored continuously at 20 °C exhibited higher levels of total anthocyanins and Phenylalanine Ammonia-Lyase activity and also elevated expression of the genes coding for enzymes involved in the biosynthesis of anthocyanins in comparison to fruits that underwent cold storage. Our results suggest that cold storage of sweet cherries at low, but non-chilling temperatures, decelerates the accumulation of anthocyanins and consequently causes slower colour development in fruits.