Effects of Steam Explosion-Assisted Extraction on the Structural Characteristics, Phenolic Profile, and Biological Activity of Valonea

Valonea, a natural product from <i>Quercus variabilis</i>, is rich in bioactive phenolic compounds; however, its compact physical structure restricts the efficient extraction of these components, limiting its high-value applications. To address this issue, the present study examined the influence of steam explosion (SE) pretreatment on the physical structure, phenolic profile, and bioactivity of valonea and identified optimal processing parameters. Under optimal conditions (1.0 MPa and 10 min), the content of total polyphenols increased by 63.1%, reaching 553.0 mg/g extract, while gallic acid and ellagic acid concentrations increased by 380.6% and 1280.0%, respectively. Electrospray ionization mass spectrometry identified 12 major phenolic constituents, providing a compositional basis for the observed bioactivities. The extract exhibited strong antioxidant and anti-inflammatory properties, confirming that SE not only augments phenolic content but also preserves or enhances the functional quality of the extract. As an efficient and environmentally friendly pretreatment technology, SE substantially improves the bioavailability and activity of phenolics in valonea. Thus, this study offers a reliable strategy for the high-value utilization of valonea in fields such as pharmaceuticals, functional foods, and animal feed.