The present invention related to a method for preparing a protein hydrolysate from a proteinaceous material by contacting the material with a proteolytic enzyme mixture having a proline specific exopeptidase. In particular, the proline specific exopeptidase is an aminopeptidase specific for at the five amino acid N-terminal sequence X-Pro-Gln-Glv-Pro-, where X is any amino acid. The present invention also relates to use of the aminopeptidase with a second exopeptidase and an endopeptidase.