Release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from milk protein isolate (MPI) during enzymatic hydrolysis
Author(s)
Date Issued
2017
Type
article
Volume
94
Start Page
79
End Page
89
Journal
Abstract
The release of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from bovine milk protein isolate (MPI) during trypsin hydrolysis was studied using a design of experiments (DOE) approach. A 3 factor×3 level DOE including temperature (40, 50 and 60°C), enzyme to substrate ratio (E:S; 0.50, 1.25 and 2.00% (w/w)) and hydrolysis time (60, 150 and 240min) was used during the generation of 15 hydrolysates (H1-H15). The degree of hydrolysis (DH) varied between 6.98±0.31 (H8) to 12.75±0.62% (H10). The DPP-IV half maximal inhibitory concentration (IC50) ranged from 0.68±0.06 (H11)/0.68±0.10 (H4) to 1.59±0.11mgmL-1 (H8). Temperature had no effect (p>0.05) on the DPP-IV IC50 value, while an increase in E:S or time significantly decreased DPP-IV IC50 value (p<0.05). The DPP-IV IC50 value of 0.69mgmL-1, predicted by response surface methodology (RSM), to be obtained with an hydrolysate generated at 50.5°C, 2% ES and 231min (H16) was similar to the experimentally obtained value (DPP-IV IC50=0.66±0.10mgmL-1, p>0.05, n=3). Following simulated gastrointestinal digestion (SGID) of H16 (H16_CorPP), the DPP-IV IC50 value increased (p<0.05) to 0.90±0.07mgmL-1. There was no significant difference between the DPP-IV IC50 value of the SGID of MPI (MPI_CorPP, 0.89±0.11mgmL-1) and that of H16_CorPP. Potent known DPP-IV inhibitory peptide sequences were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) within H16, some of which were also present within H16_CorPP. MPI hydrolysates may be of interest for serum glucose regulation in humans.