Effect of Cultivar Type and Ripening on the Polyphenol Content of Date Palm Fruit

Abstract

Date palm (Pheonix dactylifera) fruit contains an array of polyphenols, although how these levels alter with cultivar type and fruit ripening is unclear. Utilizing HPLC and LC-ESI-MS/MS, this study define and quantify an array of hydroxybenzoic acids, hydroxycinnamic acids, and flavonoids in three common cultivars of dates (Ajwa, Barni, and Khalas) at the main ripening stages (kimri, khalal, rutab, and tamr). Polyphenols were at highest concentration at earlier stages of ripening, with concentrations reducing with ripening. The khalal stage of the Ajwa cultivar contained significantly higher (P < 0.001) levels of polyphenols than measured in the Barni and Khalas dates at the same degree of ripening. Furthermore, the Ajwa cultivar was the only one to contain significant quantities of anthocyanidins, in particular at the khalal stage. These data suggest dates are a significant source of polyphenols, especially if the earlier edible ripening stages are consumed or utilized as food ingredients.

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“…12 Our data are in agreement with previous studies indicating that the phenolic content in fruit of date palm decreases as ripening progresses. 13,14,15 Similar findings have been reported by Aziz et al, 16 a general decline in total phenolic content in the pulp of banana fruit during ripening. An apparent gradual decrease in the total fruit phenolic concentrations, which is connected with an increased polyphenol oxidase activity during the ripening of the fruit.…”

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

“…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]. Initiation of ripening triggers accumulation of phenolic compounds in grapes and concentration of phenolic compounds drops to lower levels prior to commercially ripe stage [37], whereas the amount of anthocyanins in berries significantly increases in line with the development of ripening while the concentration of hydroxycinnamates drops to lower levels at the same period [38].…”

Assessment of white grape pomace from winemaking as source of bioactive compounds, and its antiproliferative activity

“…The resulting extract was passed through a C18 column (10 Â 5 cm) to remove sugars, which was achieved by their elution, following addition of 100 ml of acidified water (pH 2; HCl), followed by 300 ml of Milli-Q Ò water at a constant rate (0.5 ml/ min), using a diaphragm-metering pump (STEPDOS, Scientific Laboratory Suppliers). The Fehling test was carried out to ascertain the presence of sugars in the water extracts, as described previously (Eid, Al-Awadi, Vauzour, Oruna-Concha, & Spencer, 2013). Following the removal of sugars, the elution of phenolic compounds was achieved by addition of 400 ml of methanol.…”