Debittering and hydrolysis of a tryptic hydrolysate of β-casein with purified general and proline specific aminopeptidases from Lactococcus lactis ssp. cremoris AM2

In this study, purified β-casein was hydrolysed with trypsin to produce a bitter substrate. The role of 3 aminopeptidases, a general aminopeptidase lysyl-para-nitroanilide hydrolase (KpNA-H), X-prolyl dipeptidyl aminopeptidase (Pep X) and aminopeptidase P (Pep P) each purified from Lactococcus lactis ssp. cremoris AM2, in the hydrolysis and debittering of the tryptic hydrolysate of β-casein, was then studied. The hydrolysates were analyzed for percentage degree of hydrolysis (DH%) and bitterness score. Results indicate that the hydrolysis and debittering potential of the general aminopeptidase (KpNA-H) is limited in the absence of proline specific aminopeptidases. Statistically significant (p < 0.001) reductions in bitterness were obtained following incubation of the tryptic digest of β-casein with specific combinations of the above aminopeptidases.