CHANGES DURING MATURATION IN THE BIOACTIVE COMPOUNDS AND ANTIOXIDANT ACTIVITY OF OPUNTIA STRICTA (HAW.) FRUITS

Increasingly evidences have pointed the benefits of fruit consumption on human health due to the presence of compounds capable of acting minimizing the incidence of diseases. Although in the Northeastern Brazil the Opuntia stricta species is mostly used as living fences, it produces small fruits that are of red purplish color, and source of betalains and ascorbic acid, compounds in general correlated to high antioxidant activity. This study evaluated changes in betalain content and antioxidant activity of fruits of O. stricta during maturation. Fruits were harvested from plants grown in area of family farming and graded in four maturity stages based on skin color. Evaluations were performed using the whole fruit. The content of betacyanin in the fruit increased from 6.9 to 51.6 mg/100 g during ripening. The pulp of fruit presented a intense red purplish color. The content of total extractable polyphenols (TEP) has also increased from 32.1 to 74.02 GAE mg/100 g during maturation, although no significant difference in TEP was observed between the first two maturity stages, in which some greenish traces was still present in the color. Antioxidant activity, measured by the radical ABTS•+, presented values that increased from 3.5 to 12.3 μM Trolox/g during ripening, showing similar profile to the TEP. The changes observed for the antioxidant activity of O. stricta fruits was correlated with the content of betacyanin (r=0.85**) and phenolics (r=0.99**), which can indicate that these compounds may act by capturing free radicals, minimizing oxidative stress. Therefore, these results suggest that fruits of O. stricta are a significant source of antioxidant compounds such as phenolics and betalains.