Anti-aging Activity and Composition Analysis of Grape Pomace Oil Prepared by Acid-Thermal Pretreatment Combined with Low-Temperature Continuous Phase-Transition Extraction

To simultaneously improve the extraction rate of grape pomace oil and the retention rate of active substances, this study combined acid-thermal (AT) pretreatment with low-temperature continuous phase-transition extraction (LCPE) to prepare grape pomace oil (GPO). To evaluate the extraction effectiveness, the extraction yield, physicochemical properties, contents of major active components, and in vitro antioxidant activity of GPO were determined. Furthermore, its anti-aging activity in Caenorhabditis elegans with oxidative stress induced by four factors was ascertained and its components were characterized by gas chromatography-orbitrap mass spectrometry and ultra-high performance liquid chromatography-quadrupole high-resolution mass spectrometry. The results showed that compared with LCPE, solvent extraction and AT-assisted solvent extraction, AT-LCPE resulted in higher extraction yield of GPO (96.70%) with increased contents of total phenols, total flavonoids, and total sterols (by 104.68%–184.78%, 32.74%–186.46%, and 75.76%–129.09%, respectively) and decreased half maximal inhibitory concentration (IC₅₀, by 68.48%–84.29%) against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. GPO prepared by AT-LCPE significantly prolonged the lifespan of C. elegans with oxidative stress induced by H₂O₂, paraquat, heat, and ultraviolet B radiation (UVB), extending the average lifespan by up to 33.09% (P＜0.001). Furthermore, a total of 103 and 123 compounds were identified by the above mass spectrometry techniques, respectively; the most abundant ones were fatty acids and esters, followed by terpenoids and terpenes. GPO was rich in various substances, including typical active substances such as linoleic acid, oleanolic acid, β-tocotrienol, and β-sitosterol, rare components such as squalene and ceramide, and other components such as soyasapogenol E, ganoderic acid F, and ganoderiol I, which were discovered in the oil for the first time. Therefore, AT-LCPE is an effective measure to achieve the simultaneous and efficient extraction of oils and active components, and AT-LCPE GPO has high quality and excellent efficacy. The findings provide a theoretical basis and technical support for the high-value development and utilization of grape pomace.