Optimization of phenolic compounds recovery and antioxidant activity evaluation from Opuntia ficus indica using response surface methodology

Opuntia ficus indica (OFI) is a Cactaceae plant growing generally in arid and semi-arid regions of the world. The extraction of bioactive compounds from plants could be done by numerous methods according to the economic aspects, means, and method suitability for targeted compounds, thus, this study is aimed to optimize the extraction conditions of decoction method for phenolic compounds and antioxidant activities evaluation, using response surface methodology from edible parts of cactus fruit (seeds, pulp, and fruits). The highest results for total phenolic compounds (TPC) were 335, 568, and 524 mg GAE/100 g DM for seeds, pulp, and fruits, respectively. The highest ABTS radical scavenging activities were 1822, 4208, and 3174 mu mole TE/100 g DM, while, the reducing power (RP) was 210, 201, and 239 AAE/100 g DM for seeds, pulp, and fruit, respectively. The statistical analysis showed a significant effect of the studied parameters on extraction from all samples, except for the time that was insignificant for TPC and RP of pulp. The Response surface analysis showed that the optimal extraction parameters were 90 degrees C, 1 g/100 mL, and 30 min for temperature, sample/solvent ratio, and time, respectively (except fruits, demonstrating a ratio of 1.8 g/100 mL). In conclusion, the decoction seemed to be a good extraction method for antioxidant compounds from OFI. In addition, these latter compounds were found to be heat stable and contribute significantly to the antioxidant activity of the fruit.