Changes in quality parameters, proline, antioxidant activity and color of pomegranate (Punica granatum L.) as affected by fruit position within tree, cultivar and ripening stage

Abstract

In recent years, the pomegranate (Punica granatum L.) has acquired wide acceptance due to the growing evidence that consumption is associated with beneficial health properties. The present study was conducted to study the effect of the position of the fruits within the tree in the main quality parameters (total soluble solids, titratable acidity, pH and maturity index), the profiles of organic acid, sugars, the amino acid proline, total phenolic compounds, antioxidant activity, and the external and internal color. Analyses were performed on three Spanish pomegranate cultivars: Mollar de Elche (“ME14”), Borde de Albatera (“BA1”) y Piñon Tierno de Ojós (“PTO5”) at three ripening stages. The results showed that the position within the tree had no significant effects on total soluble solids (TSS), the titratable acidity (TA), maturity index (MI), pH, organic acids, sugars profiles, proline, antioxidant activity (AA) and total phenolic compounds (TP); however, it significantly (p<0.05) affected data on external color coordinates. External color showed a simultaneous increase in the values of a* and C* along with decreases in b* and H*; this contributed to the production of characteristic garnet color of pomegranate fruits and has high importance in deciding the appropriate harvest time. This study provides useful information about the quality parameters, proline, phenolic compound, antioxidant activity and color of three different type of pomegranate during three ripening stages. It also shows that the fruits exposed to sunlight have similar chemical composition to those fruits exposed to shade except in external color.