The appraisal of qualitative parameters and antioxidant contents during postharvest peach fruit ripening underlines the genotype significance

Several studies document that peach and nectarine ripening related parameters can be efficiently predicted in a non-destructive manner; however, such studies are being restricted in a relatively limited number of cultivars and parameters measured. In addition, the combined effect of genotype and postharvest ripening on phytochemical content of peach and nectarines has not been elucidated. In the present study, the IAD maturity index, ripening-related parameters, phenolic and flavonoid contents and in vitro antioxidant capacity were determined in fruit from 26 commercially important peach and nectarine cultivars, grown in Greece. Analyses were carried out at harvest and after additional ripening at room temperature (∼23±2 °C) for 1, 3 and 5 days, to simulate shelf life conditions. Results indicated great variation in the IAD index (variation coefficient=32%); this index can be used as reference in future studies on a cultivar basis. Flesh firmness was the strongest predicted parameter from the IAD index during off-tree ripening. Segregation of peach and nectarine cultivars revealed great differences on quality parameters and on their ripening behavior. Varietal differences were more pronounced regarding the polyphenolic content; indicatively, total phenol (TP) content ranged from 11.7 to 90.1mg gallic acid equivalents (GAE) 100−1g fresh weight (FW) at harvest. ‘Sun Cloud’ and ‘Gladys’ fruits among peach cultivars and ‘Tasty Free’ fruits among nectarine cultivars demonstrated high antioxidant contents. Interestingly, postharvest ripening of peach and nectarine cultivars did not seem to affect polyphenolic content and antioxidant capacity in a constant mode. Hence IAD was not correlated with antioxidant contents and to our knowledge this is the first work examining this correlation. Furthermore, data underlines that peach cultivars in general were characterized by higher antioxidant contents compared to nectarine cultivars; this was also the case for late-harvested cultivars versus the early-harvested ones.