Physicochemical Properties and Hypolipidemic Activity of Soluble Dietary Fiber Extracted from Ginger Peel Residue

Hyperlipidemia is a chronic metabolic disorder driven by impaired lipid homeostasis. In this study, the steam explosion (SE)-assisted extraction was applied to obtain soluble dietary fiber (SDF) from ginger peel residue. Based on single-factor and orthogonal optimization experiments, SE treatment at a material-to-cavity ratio of 2:5 and a pressure of 1.5 MPa for 300 s achieved an SDF extraction yield of 8.20%, representing a 210.60% increase. Structural and physicochemical analyses showed that both SDF and SE-SDF were mainly composed of glucose, galactose and mannose. SE treatment generated a looser and more porous structure and significantly improved the thermal stability, water holding capacity (WHC) and swelling capacity (SC) of SE-SDF increasing by 38.89% and 30.77%, respectively (p < 0.05). In oleic acid/palmitic acid (OA/PA)-stimulated HepG2 cells, both SDF and SE-SDF reduced triglyceride (TG) and total cholesterol (TC) levels in a dose-dependent manner, with SE-SDF showing a stronger hypolipidemic activity. Zebrafish experiments further confirmed that 200 µg/mL SE-SDF significantly reduced TG and TC levels by 30.58% and 24.89%, respectively, and decreased lipid deposition in the caudal vasculature and liver by 65.59% and 33.86%, respectively. These findings indicate that SE-SDF from ginger peel residue is a promising functional food ingredient for hyperlipidemia prevention.