The most effective extraction methods for walnut oil while preserving quality are cold pressing and expeller pressing. These mechanical techniques avoid high temperatures that degrade oil quality, retaining the optimal fatty acid profile for biodiesel. For larger-scale production, solvent extraction using hexane increases yield but requires post-processing to remove residual solvent. Pre-cleaning and drying the walnuts improve oil clarity and reduce moisture. Once extracted, the oil can be processed in the GlobeCore USB biodiesel plant, which preserves its chemical integrity during conversion.