Valorizing ginseng residues using dimethyl ether: Recovering functional lipids and ginsenosides

Background Red ginseng marc (RGM), a byproduct of hot water extraction, contains valuable lipid fractions and bioactive compounds. Conventional extraction methods often require harsh processing conditions and additional solvent removal steps, leading to high operational costs. Methods Dimethyl ether (DME) was used as a green solvent to extract ginseng oil from RGM. Response surface methodology (RSM) was employed to investigate the effects of temperature (303–333 K), pressure (3–7 MPa), and extraction time (20–80 min) on extraction yield, total ginsenoside content, antioxidant activity, and total phenolic content (TPC) of the extracted oil. Results Under optimal conditions (333 K, 7 MPa, 80 min), the extraction yield reached 3.37%, with total ginsenoside content of 4.22 mg g -1 dry RGM, and TPC of 1.09 mg GAE g -1 RGM. DME-extracted ginseng oil also exhibited higher antioxidant activity (9.04 mmol TE g -1 extract) and FAME content (14.93 mg g -1 dry RGM) compared to ethanol and hexane extracts. Notably, DME enabled direct extraction from wet RGM without prior drying. Conclusion Extraction from wet RGM using DME resulted in higher ginsenoside content and extraction yield, but lower FAME content, compared to dry RGM. These findings highlight the potential of DME as a versatile, energy-efficient solvent for extracting bioactive ginseng oil from both dry and wet RGM, offering practical applications in the food and cosmetic industries.