The sustainable utilization of marine bioresources has emerged as a promising strategy to develop high-value products for

nutraceutical and biotechnological applications, offering an alternative to conventional petroleum-based industries. However,

their industrial application remains limited by inefficient extraction processes, which are typically energy-intensive

and unsustainable. In this study, a biorefining approach with optimized green extraction was developed using the marine

microalga Dunaliella tertiolecta as a model biomass, with lutein as the extraction target. Ethanol, recognized for its extraction

efficiency and environmental safety, was selected as the green solvent. The extraction process was statistically optimized to

maximize lutein recovery, with the optimal conditions determined as 25 °C, 5.0 h reaction time, and 93.3 g/L solid loading.

The antioxidant activities of the lutein-containing extract obtained under these conditions were determined as follows: ABTS

IC50

of 4.4 μg/mL, SOD IC50

of 9.3 μg/mL, and FRAP of 7622.9 μmol/L. Mass balance analysis confirmed that optimized

extraction conditions improved lutein recovery by 2.4-fold, yielding 83.0 g from 1000 g of D. tertiolecta. This study highlights

the potential of optimized green solvent-based extraction for scalable lutein production, supporting sustainable biorefining

and nutraceutical applications.