Effects of the Ripening Stage on Phenolic Profile, Phytochemical Composition and Antioxidant Activity of Date Palm Fruit

Abstract

Four cultivars (Gondi, Gasbi, Khalt Dhahbi, and Rtob Ahmar) of Tunisian date palm (Phoenix dactylifera L.) fruits at 3 maturation stages, besser, rutab and tamr, were analyzed for their antioxidant activities (AA) using 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals cation, and reducing power (RP) methods. The total phenolic (TPC), total flavonoid (TFC), and condensed tannins (CTC) contents were measured. Results showed that all samples have the highest TPC, TFC, CTC, and AA at besser stage. A significant correlation (p < 0.05) was found between TPC, TFC, CTC and AA during ripening. Sixteen phenolic compounds were identified and quantified by HPLC. The major ones were caffeic, ferulic, protocatechuic, and catechin for the majority of cultivars. Our data indicate that common date fruits are rich in natural antioxidants that might be more widely used by both the general population and the food industry as a source of bioactive human health promoter phytochemicals.

Biochemical attributes of dates at three maturation stages

“…TPC was higher at early (khalal) stage and gradually decreased at final stage (tamar). The declining trend may be due to a gradual decrease of tannins or oxidation of TPC by polyphenol oxidase that distinguish the developmental stages as well as the decreasing trend of radical scavenging assay (antioxidant activity) (Amiot et al, 1995;Myhara et al, 1999;Amira et al, 2012). These decreasing values of TPC in date fruits were also reported in previous published data (Amoros et al, 2009;Awad et al, 2011a).…”

“…The antioxidant activity of the date fruit (flesh) extracts was evaluated for scavenging of the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) as described by Amira et al (2012). The 50 µl aliquot of various concentrations (25, 50, 75, 100 µg/ml) of the date fruit extracts was added to 5 ml of 0.004% DPPH in methanol.…”

Synthesis and accumulation of anthocyanins in sour cherries during ripening in accordance with antioxidant capacity development and chalcone synthase expression

“…Green sour cherries contain the highest amount of secondary metabolites in comparison with all other phases of maturation. The detected decrease in secondary metabolite contents can be reasoned by the decline of phenolic substances while the fruits ripened to mature stages [22,23]. Another possible explanation of the decrease in these natural compounds might be related to oxidation of phenolics by the enzyme polyphenol oxidase that characterizes these stages of maturity [24].…”

“…There are studies in the literature describing that in general, phytochemical content of fruits decreases during the progress of biochemical ripening reactions. For instance, the highest total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC) and antioxidant activity (AA) were detected at besser stage (unripe fruit) in dates [22]. A negative correlation among TPC, AA and progress of ripening was established, and consumption of dates at the earlier ripening stages was suggested to be able to intake of higher concentrations of polyphenols [36].…”

Alginate Edible Coating and Cold Storage for Improving the Physicochemical Quality of Cape Gooseberry (Physalis Peruviana L.)

“…The composition of the antioxidant phenolics in fruit increases during ripening, meanwhile during shelf life, antioxidants are rapidly reduced [30,31].…”