The present invention discloses a method for producing foods and/or beverage having improved taste and/or flavour, comprising reacting a microbial aminopeptidase on a protein material optionally under the co-existence of a protease, wherein said aminopeptidase has the properties of: (a) having an activity of catalyzing the reaction of specifically releasing a glutamic acid and an aspartic acid from the N-terminal of a peptide and/or a protein; (b) having 50% or more activity at pH6.0-9.0 as compared with the activity at the optimum pH; (c) having 40% or more activity after heating at 25-60.degree. C., pH7.5 for 30 minutes as compared with the activity of the non-heated enzyme; (d) having a molecular weight of about 40-60 kD as measured by SDS-PAGE and about 300-480 kD as measured by native-PAGE; (e) having a hydrolyzing activity of the aminopeptidase toward Glu-Glu dipeptide is 5 U/mg or more, preferably 10 U/mg or more.