Abstract: The defatting and decalcification of bovine bone paste before extraction of functional collagen ploypeptides was optimized with respect to the selection of defatting agent and decalcification conditions including citric acid concentration, soaking time and solid-to-liquid ratio. Absolute ethanol was found to be the best defatting solvent among the investigated three. Following one-factor-at-a-time experiments, a quadratic orthogonal rotation combination design was performed to optimize the decalcification conditions. The best results for the defatting and decalcification of bovine bone paste were obtained as a defatting rate of 97.46% and a decalcification rate of 96.53% by suspension in absolute ethanol at a solid-to-liquid ratio of 1:20 (g/mL) with shaking at 150 r/min and then decalcification for 16 h with 0.43 mol/L citric acid at a solid-to-liquid ratio of 1:21 (g/mL).

Key words: bone paste, defatting, decalcification, quadratic orthogonal rotation combination design