Preharvest chlorogenic acid treatments enhance fruit quality and affect the phenolic composition of ‘Navel’ oranges during cold storage

The storability of sweet oranges is determined by its quality at harvest. Therefore, this study explores the effect of preharvest treatments with chlorogenic acid (CGA) at 5 and 50 mg l-1 on quality traits and phenolics of ‘Navel’ oranges at harvest and during 60 days of cold storage. The results showed that weight loss and firmness were 14 % and 20 %, respectively, higher in oranges treated with 5 mg l-1 CGA than in the controls. In addition, this treatment reduced the respiration rate at harvest and during cold storage. It was observed that oranges treated with 5 mg l-1 CGA had lower maturity index values due to the fact that the titratable acidity was 12 % higher compared to the controls and those treated with 50 mg l-1 CGA. For the citrus colour index, the results showed the lower values in fruits treated with 5 mg l-1 CGA, which coincided with the accumulation of carotenoids in the flavedo. On average, the total phenolic content was 10 % lower in fruits treated with 5 mg l-1 CGA in the flavedo and juice than in the controls. These differences were mainly due to the accumulation of hesperidin. Furthermore, an increase in narirutin and CGA content was also observed in oranges treated with 5 mg l-1 CGA. In conclusion, a concentration of 5 mg l-1 CGA could be an effective strategy for improving the postharvest storability of 'Navel' oranges by regulating the maturation process and phenolic metabolism.