Composition of test mixtures—Study 1.

1) Chemical purities of the IPP, LPP, and VPP synthetic products were 93.4, 95.0 and 98.7%, respectively (Bachem, Weil am Rhein, Switzerland).2) The given amounts of tri-peptides isoleucine-proline-proline (IPP), leucine-proline-proline (LPP), valine-proline-proline (VPP) in the casein hydrolysate (CasH, Casimax, DSM Food Specialties, Delft, The Netherlands). The casein hydrolysate contained 57% protein with 5.4, 16.5 and 0.3 mg/g protein of LPP, LPP and VPP, respectively.3) Total XPP = total amount of IPP, LPP and VPP.Composition of test mixtures—Study 1.