The enzymatic pretreatment of bovine nose cartilage as a deproteinization step in the preparation of chondroitin sulfate was studied. Pepsin was found to be the best enzyme for the hydrolysis of bovine nose cartilage. Using an orthogonal array design, the optimum hydrolysis conditions were obtained as hydrolysis at 35 ℃ and initial pH 2.5 for 8 h with an enzyme load and 0.2% and a solid-to-solvent ratio of 1:5 (g/mL). Under these conditions, the yields of cartilage and chondroitin sulfate were 85.12% and 28.98...