Changes in fruit quality during ripening of two European plum cultivars

Abstract

The maturity stage at harvest is one of the main determinants of fruit quality. In order to determine the optimal harvest time of plum fruits for fresh consumption, it is important to highlight the quality changes that occur during ripening. Therefore, the aim of this study was to evaluate the physical, chemical, antioxidant and sensory properties of the fruits during ripening of two European plum cultivars, worldwide cultivated 'Stanley' and the new late-ripening plum cultivar 'Petra', released at the Fruit Research Institute, Čačak. Fruits of 'Stanley' were harvested four times during the 28-day period, while three harvests were made seven days apart for 'Petra'. Although similar patterns of change in some important quality parameters were observed in both cultivars (i.e., fruit firmness and total acidity decreased significantly, soluble solids content as well as content of total sugars, invert sugars, and sucrose increased), almost all examined physical attributes (fruit weight, stone weight, dimensions of fruit, shape index, stalk length, force of detachment stalk from fruit) changed differently among the cultivars studied during ripening. The content of total phenolic compounds and antioxidant capacity slightly decreased in 'Petra' during ripening, while no clear trend was determined in 'Stanley'. Sensory analysis included evaluation of appearance, aroma, taste and consistency of the plum fruit and the results showed that the later harvested fruits of both cultivars had better taste and aroma. The quality changes during ripening of 'Stanley' plum were significantly pronounced and consequently the fruit characteristics and suitability for fresh consumption differed between the harvests. On the other hand, overall quality of 'Petra' fruit was more consistent during the ripening period indicating that it has the potential to supply the local market with fruit of uniform quality regardless of harvest time.