Old products, new applications? Considering the multiple bioactivities of plastein in peptide-based functional food design

•Plastein is a high-molecular size protease-induced peptide aggregation product.•Plastein reaction has resulted in enhancement of bioactivities of protein hydrolysates.•Proposed peptide rearrangement in plastein can result in new bioactive sequences.•Migration of hydrophobic peptides into plastein core can also mask peptide bitterness.•Plastein is susceptible to endogenous proteolysis, limiting its use in functional food.

For over a century, plastein has remained mostly cryptic with inconclusive proof of their formation mechanisms. Although initial interest in the nutritional application of plastein decreased by the mid-1980s, the last decade has seen a reemergence of plastein as bioactive agents. It is thought that sequence variations due to protease-induced peptide modification during plastein formation are associated with the enhancement of bioactivities such as angiotensin converting enzyme inhibition (antihypertensive), calcium-chelating (anticoagulation), antioxidant and cytoprotective activities. Moreover, the clustering of hydrophobic residues during peptide aggregation has enabled exploration of plastein as peptide debittering agents, and as a bile acid sequestrant with potential endogenous cholesterol-reducing role. This article presents plastein from different perspectives with emphasis on their chemistry, bioactivity and prospective functional food applications.