Relationship between fruit density and quality parameters, levels of sugars, organic acids, bioactive compounds and volatiles of two nectarine cultivars, at harvest and after ripening

In this study, fruits of two nectarine cultivars, harvested at commercial ripeness, were sorted into three density groups. Physicochemical parameters (mean weight, firmness, dry matter, soluble solids content, titratable acidity) and the levels of sugars, organic acids, vitamin C, polyphenols and volatiles were then determined at harvest and after ripening. A sensory ranking test was also performed on ripened nectarines to compare quality attributes (firmness, sweetness, acidity, and aroma). In both cultivars, ripened nectarines of higher density had significantly higher levels of dry matter, soluble solids content, sugars, ascorbic acid, polyphenols and volatiles. Among polyphenols, the levels of hydroxycinnamic acids were 30-40% significantly higher in nectarines of higher density. Among volatiles, levels of lactones, well-known key aroma compounds in nectarines, were also 2-3 times significantly higher in ripened fruits of higher density. Consistent with these results, nectarines of higher density were significantly ranked sweeter and more aromatic in both cultivars.