Bioactive peptides are specific amino acid sequences that exert regulatory effects on various bodily functions and diseases. They remain inactive within the parent polypeptide chain until they are released by proteolytic enzymes and then exert a positive health effect upon entering the bloodstream (Sanchez and Vazquez 2017). These peptide sequences can be found in many food proteins and have been associated with antihypertensive, antioxidant, opiate, immunomodulatory, mineral binding, and bone protection properties among others.
In the last 20 years, numerous peptides with biological activity have been identified. Most of these peptides are naturally occurring, but there is also growing interest in rationally designed synthesised and optimised peptides as research tools for modulating protein-protein interactions.
Several food sources are rich in bioactive peptides, including egg proteins, milk, and wheat. Fermented foods, such as milk and cheese, are also a rich source of bioactive peptides that exert multiple beneficial effects during digestion. These effects include lowering blood pressure in hypertensive people, improving the immune system, and alleviating the symptoms of gastrointestinal diseases.
Typically, bioactive peptides are produced through enzymatic hydrolysis or microbial fermentation. They are then purified using chemical synthesis. To ensure the quality of the final product, a systematic design of experiments (DOE) approach can be applied to identify and optimize critical process parameters for the production of bioactive peptides. These factors may include the starting material, e.g., the protein content and seasonal variabilities of a particular food; the enzyme (optimal temperature and pH, purity, and specific activity); and the process conditions, such as time, temperature, and enzyme to substrate ratio.