Milk Proteins: Bioactive Peptides

Abstract

Food-derived bioactive peptides represent one source of health-enhancing components. Bioactive peptides can be released during gastrointestinal digestion or food processing from a multitude of plant and animal proteins, especially milk proteins. Milk protein-derived bioactive peptides are considered to promote diverse activities, including opiate-like, mineral-binding, immunomodulatory, antimicrobial, antioxidant, antithrombotic, hypocholesterolemic, and antihypertensive actions. The exact mechanisms behind these effects are not fully understood. Opioid peptides are opioid receptor ligands with agonistic or antagonistic activities. Caseinophosphopeptides can form soluble organophosphate salts and may function as carriers for different minerals, especially calcium. Immunomodulating casein peptides stimulate proliferation of human lymphocytes and phagocytic activities of macrophages. Antimicrobial peptides kill sensitive microorganisms. Antithrombotic peptides inhibit fibrinogen binding to a specific receptor region on the platelet surface and also inhibit aggregation of platelets. Antioxidant peptides prevent peroxidation of essential fatty acids. Angiotensin-converting enzyme (ACE) inhibitory peptides can exert an antihypertensive effect. By modulating and improving physiological functions, bioactive peptides may therapeutic applications for the prevention or treatment of chronic diseases. This article reviews the current knowledge of the existence of milk protein-derived bioactive peptides, in vitro bioactivity, production, and the present evidence of health effects exerted by bioactive peptides.