Abstract

The composition and the antioxidant activity of the juicy pulp of four Opuntia ficus-indica varieties (green, yellow, orange and red) grown in North Algeria were investigated. The juicy pulp was characterized by a high humidity (87.4 to 89.6%), high pH (6.2 to 6.6), low acidity (0.04 to 0.07%), a few amount of proteins (0.35 to 0.49%) and high amount of solid soluble compounds (12 to 15%). Among the four varieties, the orange variety showed higher values concerning the last parameters. The same variety was also richer in phenolic compounds with 66.60 mg AGE/100 g, carotenoids (2.65 mg eq. β-carotene/100 g) and betaxanthin (6.79 mg/100 g). High ascorbic acid content has been recorded (28.76 mg AAE/100 g). However, betacyanin and total betalains contents were obtained in red juicy pulp. Following this rich composition in antioxidants, the four varieties studied showed performances in reducing iron F³⁺, inhibiting hydrogen peroxide and decreasing the DPPH concentration by 50%. The best activities were obtained with the orange juicy pulp extract followed by the red one.  In addition, direct relationship was noticed between the antioxidant and antiradical capacities of the ethanol extracts and the phenolic compounds concentration and also within the three activities.

Key words: Opuntia ficus-indica, physical and chemical properties, antioxidant, antiradical activities.