Integrated PEF–Supercritical CO₂ Technology for High-Purity Astaxanthin Extraction from Haematococcus pluvialis

Astaxanthin, a high-value xanthophyll carotenoid with potent antioxidant activity, was efficiently extracted from the microalga Haematococcus pluvialis using an integrated green extraction strategy combining pulsed electric field (PEF)-assisted cell disruption and supercritical CO₂ (SC-CO₂) extraction. The study establishes a sustainable and high-efficiency protocol wherein biomass preconditioning via mechanical pulverization and optimized PEF treatment enabled effective permeabilization of the robust sporopollenin-rich cell wall, thereby enhancing intracellular release of esterified astaxanthin. Subsequent extraction using SC-CO₂ at optimized conditions (450–500 bar, 60–65°C) with acetone as a co-solvent significantly improved solubility and recovery of non-polar carotenoids while preserving thermolabile integrity. The process yielded approximately 350 mL of carotenoid-rich oleoresin from 1 kg of dried biomass. Further purification through chloroform–water liquid-liquid partitioning enabled selective enrichment of astaxanthin in the organic phase, resulting in a high-purity extract. Quantitative analysis using a validated HPLC gradient method (ICH Q2 R1 compliant) revealed an astaxanthin concentration of ~9.9% in the final extract, confirming the robustness, reproducibility, and analytical reliability of the developed method. Compared to conventional solvent-based, microwave-assisted, and ultrasonication techniques, the integrated PEF–SC-CO₂ approach demonstrated superior extraction efficiency, reduced solvent toxicity, and enhanced environmental compatibility. This study highlights a scalable, green, and industrially viable extraction platform for high-purity astaxanthin production, with significant implications for applications in nutraceuticals, pharmaceuticals, cosmetics, and aquaculture. The integration of non-thermal cell disruption with supercritical fluid extraction represents a next-generation paradigm in microalgal bioprocessing. Future perspectives include further process intensification, solvent system optimization, and techno-economic scaling for commercial deployment.