Ultrasound-Assisted Extraction of Spirulina platensis Carotenoids: Effect of Drying Methods and Performance of the Emerging Biosolvents 2-Methyltetrahydrofuran and Ethyl Lactate

Extracting bioactives from algae is essential for sustainable solutions aimed at enhancing human health. This study pioneers a multidimensional approach that simultaneously compares ultrasound-assisted carotenoid extraction from spray-dried (SD) and solar-dried (SolD) Spirulina platensis, evaluating both food-grade and emerging green biosolvents, validated through COSMO-SAC predictions and optimized using RSM. The SD sample showed higher carotenoid yields with most solvents, consistent with particle size data indicating less aggregation than SolD. Solvent efficacy varied depending on drying method and carotenoid type; acetone was optimal for zeaxanthin and β-carotene from SD and β-carotene from SolD, while methanol and ethanol were more effective for zeaxanthin in SolD. The green solvent 2-methyltetrahydrofuran (2-MeTHF) demonstrated excellent carotenoid affinity in COSMO-SAC predictions and ranked as the second most effective solvent in the SD sample, underscoring its potential as a sustainable alternative. RSM models using 2-MeTHF (SD) and ethanol (SolD) showed excellent prediction accuracy (R2 > 98%). Optimized extraction conditions yielded ~4-fold higher total carotenoid recovery compared to non-optimized conditions. Combining computational tools and experiments offers an effective strategy to optimize sustainable extraction of health-promoting carotenoids from Spirulina.