When FFAs in chicken fat exceed 2–3%, a two-step process is recommended: 1) Acid esterification using sulfuric acid to reduce FFAs, followed by 2) Base-catalyzed transesterification with NaOH or KOH. This prevents soap formation and ensures high biodiesel yield. The GlobeCore USB plant supports this dual process, automating acid and base reaction stages with precise temperature and mixing control. For lower FFA levels, base catalysis alone is sufficient.