Enhancement of the antioxidant activity of a by-product (Phoenix dactyliferaL.) from the Agri-food industry

Abstract

Despite their biological value, date seeds as by-product are not quite studied, compared to analogue agricultural wastes. In addition to the basic physiochemical characterization, the antioxidant power (AP) of by-product (Phoenix dactyliferaL.) seeds (DS) is presently investigated. The AP was evaluated through the reducing power (RP), as well as antiradicalar activity (AA) of extracts obtained with different solvents (water, methanol, ethanol, acetone, chloroform, and hexane). Except hexane and chloroform, all other employed solvents give extracts with RP above 0.3 optic density units. Concerning the AA, all extracts obtained with cold extraction display a highest antioxidant activity for a dried extract concentration of 0.6 -0.7 mg ml-1. In addition, the most important AA (> 90%) is found for BHT, vitamin E, ethanolic and methanolic extracts, whereas the least values (70-80%) report to the acetone and chloroform extracts. The similar results are also found when the hot extraction is applied. On the other hand, the most interesting correlations (R2>0.94) are reached for combinations of type polyphenols/RP (case of extraction with pure ethanol and 50% -acetone), and flavonoids/RP (in the unique case of the extraction with 50%-acetone). Given their antioxidant potential, DS extracts can be recommended as an ingredient in various food and non-food formulations.