EVALUATION OF ANTIOXIDANT ACTIVITY, PHENOLICS, SUGAR AND MINERAL CONTENTS IN DATE PALM FRUITS

Abstract

ABSTRACT Sugar and mineral compositions of 10 Tunisian date varieties were investigated. Hydrophilic (aqueous extract) and hydrophobic extracts (ethanol extract) were used to determine the phenol contents and the total antioxidant activities of these dates. Results showed that date fruit varieties were rich in soluble sugars, which varied from 35.57 (Smiti variety) to 77.88 g/100 g fresh weight (FW) (Korkobbi variety). Several minerals were also present in the following order; K, Ca, P, Mg, Na, Fe, Cu, Zn and Mn. The potassium content reached 0.74 g/100 g dry weight in Smiti variety. For all date varieties, the phenol content did not exceed 9.70 (milligram of gallic acid equivalent/100 g FW). The original antioxidant activity reached 31.86 mg of ascorbic acid equivalent antioxidant capacity/100 g (FW) for Garn ghzal variety. However, it was only 17.77 for the Nefzaoui. Therefore, it can be deduced from these results that all these fruit varieties can be considered as high-energy food and only Garn ghzal seems to be interesting for technological purposes as food antioxidants. PRACTICAL APPLICATIONS The date palm (Phoenix dactylifera L.) has a very important economic, social and ecological role for the people of the arid and semiarid regions. The date world production tripled while passing from 2,289,511 tons in 1974 to 6,772,068 tons in 2004. In Tunisia, dates witnessed a remarkable development during the last years and the production reached an average of 110,000 tons per year. Unfortunately, this progress in production is accompanied by an increasing loss of secondary varieties. Among these abandoned varieties are those of Gabès oasis. In this context, our work focuses on valorizing these secondary varieties by determining their nutritional and medicinal properties.