Temperature-responsive surfactant-free microemulsion solvent: Preparation, characterization and application of extraction hydrophobic and hydrophilic components in plant matrix

In this study, a novel temperature responsive surfactant-free microemulsion (SFME) solvent was prepared and fully characterized. Combined with ultrasonic assisted extraction (UAE), it was applied to the simultaneous extraction and enrichment of different hydrophilic and hydrophobic components in Rosa roxburghii leaves. The extraction factors such as solid-liquid ratio, extraction temperature and extraction time were optimized by response surface methodology. The extraction yields of components with different polarity were improved by 1.03–3.90 folds compared with traditional solvents. The extraction mass transfer process was fitted by first-order kinetic model and second-order kinetic model. The results showed that the fitting effect of second-order kinetic model was better. Moreover, molecular dynamics revealed that hydrogen bonds were formed between the solvent and the compound molecules then promoted the improvement of extraction capacity. Notably, in situ separation and recovery of compounds with different polarities were conducted by SFME and the recovered extracts had good antioxidant capacity. In conclusion, this novel SFME was environment-friendly and simultaneously appropriate for the effective extraction and enrichment of natural active compounds from plant matrix.