BACKGROUND: The large amount of limed bovine split wastes discharged by the leather industry has raised concerns regarding their environmental effect. The objective of this work was to perform pilot plant trials to extract high-value native collagen from these wastes through improved pretreatment methods. RESULTS: EDTA- and HCl-pretreatment gave similar removal percentages of inorganic substances. Owing to the open structure of fibers, the collagen yield of HCl-pretreated splits (HPS) (41.31%) was higher than that of EDTA-pretreated splits (EPS) (10.42%). Furthermore, HCl-pretreated split collagen (HPC) had a more acidic isoelectric point, lower content of primary amino groups, larger Z-average particle size and higher relative viscosity than EDTA-pretreated split collagen (EPC). Electrophoretic analysis and circular dichroism spectra revealed the maintenance of polypeptide and triple helix conformation, respectively. In addition, the transition temperatures of EPC (34.7 degrees C) and HPC (34.6 degrees C) detected by differential scanning calorimetry (DSC) were close to that of commercial collagen from calfskin (CCC) (35.7 degrees C). CONCLUSION: A process of native collagen extraction from limed bovine split wastes was proposed. While both EPC and HPC represented similar physicochemical properties to those of CCC, the collagen yield of HPS was much higher than that of EPS. (C) 2008 Society of Chemical Industry.