Pulsed Electric Field-Assisted “Green” Extraction of Betalains and Phenolic Compounds from Opuntia stricta var. dillenii Prickly Pears: Process Optimization and Biological Activity of Green Extracts

Opuntia stricta var. dillenii (OPD) fruits are rich in betalains and phenolic compounds, which are recognized for their potential health-promoting properties. This study focuses on the optimization of pulsed electric field (PEF)-assisted solid-liquid green extraction (SLE) from OPD whole fruit, using response surface methodology (RSM) experimental design to obtain green extracts rich in bioactive compounds. The optimal PEF pre-treatment conditions (electric field strength and energy input) were determined based on the cell disintegration index (Zp), followed by optimizing SLE conditions (temperature, time, and ethanol content). High-performance liquid chromatography (HPLC-DAD-ESI-Qtof) was used to characterize the individual bioactive compound profile of the obtained OPD green extracts. Results showed that optimal PEF pre-treatment conditions were at 10.5 kJ/kg and 5 kV/cm, followed by SLE at 35 degrees C for 165 min, using water as the solvent. Conventional optimal SLE conducted at 45 degrees C, 8% ethanol, and 128 min was applied as the control process. The combined PEF-assisted SLE process enhanced total betalain and phenolic compound yields by 61% and 135%, respectively. Antioxidant activities (DPPH by 145%, FRAP by 28%) and anti-inflammatory potential (hyaluronidase inhibition by 19%) were also significantly improved. This study underscores the potential use of a PEF pre-treatment to improve obtaining green extracts rich in bioactive compounds with high biological activities from OPD whole fruits, using water as a solvent.