Abstract

TOTAL PHENOLIC CONTENTS AND ANTIRADICAL ACTIVITIES OF POMACES AND THEIR INGREDIENTS OF TWO IRAQI DATE (Phoenix dactylifera L.) CULTIVARS

Abdul-Lateef Molan*, Ashwaq A. Yousif and Nagham Y. Al-Bayati

ABSTRACT

The objective of the present study was to determine the total phenolic content (TPC) and antioxidant activities of the extracts prepared from the date by-products [pomaces and their ingredients (flesh and seeds)] of two Iraqi date cultivars (Zahdi and Kestawi) using five different solvents. The TPC was measured using Folin–Ciocalteau method; while the antioxidant activity was measured using DPPH-radical scavenging and Ferric reducing/ antioxidant activity (FRAP) assays. The results showed that the type of the solvent used in the extraction plays an important role in determining the TPC and the antioxidant activity of the pomaces and their ingredients (flesh and seeds) of dates. Tow solvents (distilled water containing 1% and 5% of hydrochloric acid) have been used for the first time for preparation of the extracts from the pomaces and their ingredients and these solvents showed superiority in terms of the quantity of the phenolic compounds and the antioxidant activity over the other solvents (distilled water only, 50% ethanol, and sometimes boiling water). The extracts prepared from the entire pomace, flesh and seeds of Zahdi cultivar had significantly higher (P< 0.5) TPC, free radical scavenging activity and higher reducing power than their counterparts from Khestawi cultivar and in all solvents used. Strong and positive correlation was found between the TPC and the antioxidant activity, indicating that the phenolic compounds are the main ingredients contributing to the antioxidant activity of the two Iraqi date cultivars. In conclusion, the results of the present study showed that the determination of TPC and antioxidant activities was dependent on the extracting solvent used and the cultivar of the date and that the date by-products could be considered as a potential source of antioxidants and may be used as alternatives for the synthetic antioxidants in pharmaceutical and food formulations.

Keywords: Total phenolic contents, Antioxidant activity, date pomace, date seeds.