From Decoction to Microencapsulation: Opuntia ficus-indica Flowers as a Functional Polyphenol Source for Dietary Supplements

Opuntia ficus-indica flowers represent a valuable source of phenolic compounds with promising antioxidant properties, although their application is limited by the poor stability and bioavailability of these bioactives. This study aimed to identify the most effective extraction method for maximizing polyphenol recovery and to develop a spray-dried microparticulate delivery system capable of improving the stability and release of the freeze-dried extract. Different extraction techniques were compared by determining total phenolic content (TPC), antioxidant activity and individual phenolic compounds by HPLC-UV. Among the investigated methods, decoction proved to be the most efficient, exhibiting the highest TPC (27.59 mg GAE/g), antioxidant capacity (DPPH: 0.53 mmol TEAC/100 g d.e.; ABTS: 0.79 mmol TEAC/100 g d.e.; FRAP: 43.18 mg Fe2+/100 g d.e.) and the greatest overall recovery of polyphenols. HPLC analysis identified quercetin as the predominant flavonoid (57.07 mg/g), followed by kaempferol rhamnoside and quercetin-3-rhamnoside. The selected extract was successfully encapsulated by spray-drying, producing spherical microparticles (MPs) with a process yield of 64%. SEM, DSC and FT-IR analyses confirmed suitable morphology and enhanced thermal stability. In vitro dissolution and ex vivo permeation studies demonstrated a faster initial release and enhanced early quercetin permeation of MPs across porcine colon mucosa compared with the freeze-dried extract. These findings highlight spray-dried microparticles as a promising strategy for improving stability, bioaccessibility and nutraceutical potential of O. ficus-indica flower polyphenols.