A novel biorefinery approach for flaxseed oil and protein co-production using bio-based solvents

Industrial-scale flaxseed oil extraction currently relies heavily on petroleum-derived n-hexane, raising significant concerns regarding environmental sustainability and food safety. This study presents a comprehensive biorefinery strategy for flaxseed processing, integrating bio-based solvent extraction of high-quality oil with the subsequent valorization of defatted meal. Through Hansen solubility parameter-guided screening and hurdle technology, three bio-based solvents were selected from a pool of 34 candidates. Among them, 2-methyloxolane (2-MeOx) outperformed n-hexane in both oil yield and quality, yielding oil with superior levels of bioactive lipid concomitants and meeting national physicochemical standards. Mechanistic investigations that combine extraction kinetics and molecular dynamics simulations revealed that the enhanced extraction efficiency arises from synergistic dissolution-diffusion behavior. Importantly, defatting with these green solvents preserved the protein purity, amino acid profile, and functional properties of the recovered proteins, with structural characteristics largely maintained, thereby enabling effective value-added utilization of the defatted meal. Full-process assessments using Green Star metrics and EcoScale highlighted the environmental friendliness of this approach. Preliminary economic analysis showed the industrial potential of 2-MeOx as a n-hexane alternative. Collectively, this work demonstrates that bio-based solvent systems, particularly 2-MeOx, offer a technologically viable and environmentally benign platform for the sustainable biorefinery of oilseeds, facilitating both primary oil production and secondary protein recovery in a circular bioeconomy framework.