Bioactive peptides— large-scale preparation

Several scientific studies have revealed that ingestion of some enzymatic hydrolysates of food proteins, namely, mixtures of peptides, produces various beneficial activities beyond basic nutritional values. Moderation of hypertension and hyperlipidemia is considered as one of these beneficial effects. The emerging market for nutraceuticals and functional foods is stimulating the production of enzymatic hydrolysates of milk, animal, fish, egg, and plant proteins on an industrial scale. Growing worldwide interest in biodiesel and bioethanol production have encouraged consideration of possible added value to be obtained from the by-products arising from their manufacture. The production of bioactive peptide fractions from protein by-products is one attractive approach. The identification of an active peptide from a mixture of peptides is the initial step required in determining its potential health beneficial properties. In most cases, the active peptides are tentatively identified by high-performance liquid chromatography (HPLC) separation and in vitro assays using enzyme and cell culture systems. Unlike many other functional substances, however, peptides are susceptible to degradation during the process of digestion and lose their desired activity. Therefore, the beneficial effects determined in vitro cannot be directly linked to those present following digestion. The potential activity of the peptides must be evaluated through feeding experiments. Although liquid chromatography (LC) is the most powerful tool for isolation of peptides, it is a relatively expensive system for large-scale preparations, especially for the first purification step. In addition, some solvents frequently used in LC, such as methanol, acetonitrile, and trifluoroacetic acid are harmful, but peptide fractions obtained with low selective techniques such as filtration have been used for feeding experiments. Nonetheless, a large-scale, low-cost, and biocompatible procedure for peptide fractionation is needed.