Methods for treating tissue matrices and tissue matrices produced according to the methods are provided. The methods can include treating a tissue matrix with a proteolytic enzyme to produce a desired pliability of the tissue matrix and/or to control the immunogenicity of the tissue matrix. The methods can also comprise performing an assay to determine if contacting the at least one collagen-containing tissue matrix with a proteolytic enzyme has altered the at least one collagen- containing tissue matrix to reduce a human immune response to the tissue matrix. The methods can comprise treatment with alcalase under conditions controlled to produce a desired pliability without unacceptable alteration in collagen structure.
