β-Lactoglobulin, a major allergen of cow′s milk, has been conjugated with the N -hydroxysuccinimide ester of the dextran-glycylglycine adduct (DG-ONSu) to reduce its immunogenicity. Since the marketed low-allergenized milks have a serious problem concerning the bitter taste introduced in the process of proteolysis and heat-treatment, we examined in this study using a sensory test, the effects of proteolysis by trypsin and heat-treatment on the taste of the conjugate (DG-β-lactoglobulin). DG-β-lactoglobulin indicating a resistance against peptidases did not show any changes in the bitter-scores by the proteolysis using trypsin, while that of the nativeβ-lactoglobulin significantly increased. Moreover, the bitter taste of the proteolytic DG-β-lactoglobulin was remarkably suppressed due to the shielding action of DG-ONSu on the bitter-taste amino acids.