Plum oil cake protein isolate: A potential source of bioactive peptides

In this study some functional properties and the in vitro digestibility of protein isolates from plum oil cakes, obtained by supercritical fluid extraction and cold pressing, as a control, were described and compared. Amygdalin contents in the protein isolates were at amounts considerably lower than regulatory. Solubility profiles of both protein isolates were typical for this type of plant proteins. Proteins showed good digestibility, which was assessed by gastrointestinal proteases (pepsin and pancreatin). SDS-PAGE analysis was used for characterisation of protein digests which showed that the protein isolates were completely digested. In vitro antioxidant capacity by three complementary methods and enzyme inhibitory effects towards Angiotensin-I Converting Enzyme (ACE) related to the onset of hypertension were determined. All obtained protein hydrolysates acted as DPPH and ABTS scavengers, as reducing agents and also as ACE enzyme inhibitor. Hence, the protein isolates obtained from plum kernel cake showed to be a potential source of natural products for food applications, with good digestibility and beneficial bioactive properties.