Chiang Mai Journal of Science

 Eustigmatos vischeri is an oleaginous microalga abundant in high-value lutein, whereas conventional organic solvent extraction is limited by low efficiency and poor environmental compatibility. As green alternative solvents, deep eutectic solvents (DESs) exhibit excellent solvation performance and eco-friendly characteristics for bioactive compound extraction. In this work, a DES-based green extraction approach was optimized for lutein recovery from Eustigmatos vischeri. Key parameters, including DES type and solid–liquid ratio, were preliminarily screened via single-factor experiments. Box–Behnken response surface methodology was further employed to optimized the extraction conditions. The maximum lutein yield of 11.234±0.272 mg/g was achieved under the optimal conditions: solid–liquid ratio of 1:60, DES molar ratio of 1:2, and water content of 20%, which was superior to traditional extraction methods. Extraction kinetics were analyzed to clarify the extraction mechanism. The extraction process was well fitted by the pseudo-second-order kinetic model, revealing that lutein extraction was predominantly governed by intraparticle diffusion and solvation interactions. This study provides a promising strategy for green and efficient extraction of lutein from microalgae. The established green process presents advantages of low cost and high extraction efficiency. The clarified kinetic mechanisms offer reliable theoretical guidance for the large-scale industrial extraction of microalgal lutein and the green separation of similar carotenoid products.