Antioxidant capacity, antioxidant compounds and antioxidant enzyme activities in five date cultivars during development and ripening

Antioxidant capacity, antioxidant compounds and antioxidant enzyme activities in dates of five cultivars during development and ripening were studied in the 2009 and 2010 seasons. Fruit growth followed a smooth sigmoid curve with maximum weight at the bisir stage. Both the antioxidant capacity measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the antioxidant compound (phenols, tannins and vitamin C) concentrations decreased from young stages through to the maturation and the ripening stages. The antioxidant capacity was highly positively correlated with the concentration of antioxidant compounds in most cultivars. The activities of the antioxidant enzymes, peroxidase, catalase and polyphenoloxidase (PPO) increased from the hababouk through to the kimri and/or the bisir stage, upon cultivar, and thereafter, declined at the ripening stages. The possible relation of these biochemical changes with fruit maturation and ripening was discussed.