Background: Opuntia ficus-indica (OFI) cladodes are valuable and underestimated by-products that provide significant amounts of biologically active compounds. In this paper, microwave-assisted extraction (MAE) was performed for the recovery of phenolic compounds from OFI cladodes using two approaches: response surface methodology (RSM) and artificial neural network–genetic algorithm (ANN-GA), which were then compared following statistical indicators. Materials and Methods: Four independent factors were employed in the optimization process (solvent concentration, microwave power, irradiation time, and solid-to-liquid ratio) by selecting the total phenolic content (TPC), estimated by the Folin–Ciocalteu method, as a response. The optimized extract was tested for antioxidant capacity using the Folin–Ciocalteu reagent, Trolox Equivalent Antioxidant Capacity (TEAC), and oxygen radical absorbance capacity (ORAC) assays and for antimicrobial activity against 16 pathogenic strains using the agar well diffusion method. Results: The maximum TPC values predicted with maximizing desirability function for RSM were 2177.01 mg GAE/100 g DW and 1827.38 mg GAE/100 g DW for the ANN. Both models presented certain advantages and could be considered reliable tools for predictability and accuracy purposes. Using these conditions, the extract presented high antioxidant capacity for FCR assay (13.43 ± 0.62 mg GAE/g DW), TEAC (10.18 ± 0.47 µmol TE/g DW), and ORAC (205.47 ± 19.23 µmol TE/g DW). The antimicrobial activity of the optimized extract was pronounced only with respect to S. aureus alimentarius, Streptococcus, E. coli, P. aeruginosa, and A. flavus. Conclusions: This study underlines the high effectiveness of the optimization approaches in providing a maximum recovery of bioactive compounds from OFI cladodes to formulate food and pharmaceutical products with functional qualities.

Functional ingredients rich in bioactive compounds can be added to conventional ingredients for the formulation of food to increase its nutraceutical potential. Three prickly pear parts, namely flowers, seeds, and seed cake were utilized in the current work as natural antioxidant resources. The flower extract gave the best amounts of antioxidants as estimated by spectrophotometric methods, which were 68.08 mg GAE/100 g DM for total phenolics; 6.91 mg QE/100 g DM for total flavonoids; 13.05 mg QE/100 g of DM for flavonols; and 0.22 mg/100 g of DM for condensed tannins. The three extracts showed a high proportion of antioxidant effect as determined by DPPH, ABTS, FRAP, and TAA in vitro assays. Chemical analysis and sensory testing were performed on biscuits that were made by adding powdered flowers, seeds, or seed cake. The biscuits made from the seed cake gave a higher protein content (83.97 mg/100 g) and the biscuits made from the seeds had the best ash concentration (3.21%), while the biscuits containing flower powder had the highest anti-radical activity (81.04%). Sensory analysis disclosed the preference for biscuits formulated with flowers or seeds (80%) by the experts. These findings demonstrated that the nutritional value of the biscuits was improved by their enrichment with cactus parts powders, and they were appreciated by tasters.