Antioxidant properties of crude and cold ethanol precipitated protein from palm kernel cake (PKC) As potential cosmeceutical agent

Abstract

Palm kernel cake (PKC) is a by-product obtained from the production of edible oils using oil palm (Elaeis guineensis). PKC is well-known for its high protein content, therefore, it was chosen as the target of this research to study its antioxidant properties, which is an important criteria in cosmeceutical industry. Our studies showed that, the extraction of crude protein at 80°C resulted in the highest total phenolic content (TPC) and protein yield. It was further seen that precipitation using 80% cold ethanol following protein extraction at 80°C gave the best protein yield of 56.6%. The antioxidative activity of this precipitated protein was expressed as IC50 for 1-diphenyl 1-2-picrylhydrazyl (DPPH) radical-scavenging capacity (517±0.016 mg ml-1), 2, 2'-azino-bisC3-ethylbenzothia zoline-6-sulphonic acid (ABTS) radical-scavenging capacity (0.047±0.009 mg ml-1) and ferrous ion-chelating (FIC) ability (21±0.13 mg ml-1). Meanwhile, the reducing power and TPC were 0.156±0.006 trolox equivalent antioxidant capacity (TEAC) mmol g-1 dry weight (DW) and 25.10±0.58 gallic acid equivalent (GAE) μg g-1 DW respectively. The Pearson correlation test further revealed a significantly moderate to strong positive relationships between antioxidant properties with protein content and antioxidant properties with TPC. Taken together, both, the crude and precipitated protein obtained from PKC showed substantial amount of antioxidative activities, which could be used as sustainable source of antioxidant peptides in enhancing the quality of cosmeceutical products.