Palm kernel cake (PKC) proteins were hydrolysed in the presence of seven proteolytic enzymes.
The antioxidant and antihypertensive activities of each protein hydrolysate were evaluated.
Papain-generated protein hydrolysate showed the highest antioxidant effects measured by
radical scavenging activity (65%), iron (Fe)(II)-chelating activity (65%), and antihypertensive
activity (71%). The results revealed a strong correlation between the antioxidant activity of
the protein hydrolysates with angiotensin-converting enzyme (ACE) inhibitory activity (R2
= 0.69 - 0.98), except for trypsin-generated hydrolysate (R2 = 0.22). The most potent protein
hydrolysate was fractionated and profiled using reversed-phase high-performance liquid
chromatography and isoelectric focusing; peptides were subsequently isolated and identified
by tandem mass spectrometry. The individual peptides were evaluated for antihypertension
potential. A positive correlation was identified between radical scavenging activity and Fe(II)-
chelating activity together and ACE inhibitory activity with R2= 0.69 - 0.98. The findings indicate that there was a positive relationship between the antioxidant and antihypertensive activities of protein hydrolysates and bioactive peptides from PKC proteins.