Fig. 3

a Free amino acid profiles of casein hydrolysates. The contents of 19 amino acids in the control (without XPO DUET treatment [white bar]) and after treatment with 0.1 U of XPO DUET (light gray bar), 0.2 U of XPO DUET (dark gray bar), and 0.4 U of XPO DUET (black bar). b Degree of hydrolysis (%) of casein hydrolysate in the control (without XPO DUET treatment [white bar]) and after treatment with 0.1 U of XPO DUET (light gray bar), 0.2 U of XPO DUET (dark gray bar), and 0.4 U of XPO DUET (black bar). The degree of hydrolysis is presented as the relative content of free amino acids present after treatment with 6 N HCl at 110 °C for 15 h