Quality Characterization and Anti-Fatigue Properties of Yak (Bos grunniens) Leather Gel in a Mouse Endurance Swimming Model

As a major by-product of yak (Bos grunniens) processing, yak skin remains largely underutilized. In this study, a novel functional food, Yak Leather Gel (YLG), was developed, and its quality, flavor characteristics, and anti-fatigue activity were systematically evaluated with Colla Corii Asini (CCA) as a reference. YLG exhibited significantly higher iron and proline contents than those in CCA, suggesting a distinct nutritional potential. For flavor analysis, volatile compounds were assessed based on odor activity values (OAVs). In YLG, nine compounds were identified as key aroma contributors. YLG maintained typical baked notes while displaying characteristic nutty and smoky aromas, primarily derived from pyrazine compounds, which distinguished it from CCA. Importantly, YLG supplementation showed stronger anti-fatigue effects than CCA in an animal model. In mice, YLG significantly prolonged exhaustive swimming time, increased the levels of liver glycogen, glucose, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and ATP, and decreased blood malondialdehyde (MDA) and lactate dehydrogenase (LDH). These biochemical changes indicated enhanced energy metabolism and reduced oxidative stress. Furthermore, YLG increased the relative abundance of exercise-related beneficial gut microbiota. These findings indicate that YLG exhibits promising anti-fatigue activity compared with CCA, which may be linked to improved energy metabolism, enhanced antioxidant capacity, and beneficial modulation of gut microbiota. The findings support the value-added utilization of yak skin as a high-quality functional food ingredient, providing a theoretical basis for further product development.