A method to produce flavor enhancer comprises the steps of hydrolyzing protein source in presence of catalysts at an operating temperature of 25° C. to 60° C. and pH 4 to 8 to form hydrolysate； or using strong acid on defatted protein source at high temperature above 95° C.； maintaining the pH of the hydrolyzing process； deactivating the catalysts in the hydrolysate； adjusting pH of the hydrolysate to 3.5-4.5 with calcium carbonate or acid； and filtering the hydrolysate through layers of activated carbon and/or calcium carbonate to obtain the flavor enhancer.
