Methods are provided herein for modifying antigenic carbohydrate epitopes within a xenographic bioprosthetic tissue by oxidation of vicinal diols to form aldehydes or acids and subsequence reductive amination of aldehydes to form stable secondary amines, or amidation or esterification of acids to form stable amides or esters. Advantageously, methods provided herein mitigate the antigenicity of the bioprosthetic tissue while leaving the overall tissue structure substantially undisturbed, and thereby enhance the durability, safety and performance of the bioprosthetic implant.