Microbial Community, Fatty Acid Composition, and Health Potential of Horse Oil Fermented with Barley Nuruk

This study investigates the multifunctional potential of horse oil fermented with barley nuruk, a traditional fermentation starter, focusing on its α-glucosidase inhibitory activity and bioactive applicability. Gas chromatography–tandem mass spectrometry (GC-MS/MS) revealed significant changes in fatty acid composition during fermentation, with oleic acid amide and palmitic acid amide remaining stable and stearic acid amide forming prominently by day 10. Molecular docking demonstrated that the amide structures play a key role in α-glucosidase inhibition through essential hydrogen bonding interactions. Next-generation sequencing (NGS) analysis showed a notable reduction in pathogenic bacteria, such as Salmonella enterica, and a dominance of Lactobacillus acidophilus (95.2%) by day 10. The α-glucosidase inhibitory activity increased progressively with fermentation, with the day 10 extract surpassing the synthetic inhibitor acarbose, highlighting its potential for diabetes management. A human skin primary irritation test confirmed the hypoallergenic nature of both hexane-extracted and fermented horse oil products, ensuring their safety for topical applications. In conclusion, fermented horse oil demonstrates significant α-glucosidase inhibitory activity and proven safety, positioning it as a promising natural resource for therapeutic and functional product development. Further studies are needed for clinical validation and commercialization in diabetes management and related applications.