Proteomic and peptidomic analysis for characterization of food matrices

he discovery of functional natural compounds in raw or processed foods is emerging as a topic of great importance in food science. The interest in these compounds resides in their different biological and nutritional properties, which also include the potential health benefits. Typical compounds include functional fatty acids, vitamins, phenolic acids, flavonoids, but also proteins and peptides. These two last were not much studied until the improvement of proteomic analysis. The study of bioactive peptides found in various food products represents a new field of research and application field of proteomic analysis. The bioactive peptides derived from food are constituted by short sequences of amino acids (mainly from 2 to 20, with some up to 40 residues) are inactive within the native protein, but that once hydrolyzed may show numerous biological activities. These peptides can be released in different ways: during the gastrointestinal digestion, by hydrolysis in the food, with the maturation, fermentation or cooking, or by hydrolysis in vitro due to proteolytic enzymes. The bioactive peptides have a wide range of biological functions such as antimicrobial, lowering of blood pressure and cholesterol, antithrombotic and antioxidant. They can be used as functional compounds, additives for foods, bio-preservatives or pharmaceutical products. In order to investigate the presence and activity of bioactive peptides, the proteomics and peptidomics analysis have recently been applied to the study of different food matrices. These techniques are generally based on separation techniques, such as gel electrophoresis (mono and two-dimensional) or liquid chromatography, coupled to high-resolution mass spectrometry. The results are then extracted with bioinformatic tools dedicated, in order to obtain the protein identifications, peptide sequences and the biological functions. There are several databases of bioactive peptides studied until now, as PeptideDB, BIOPEP and CAMP; CAMP is a specific database for antimicrobial peptides and has a free tool to predict the bioactivity of peptides not previously studied. Another important goal of discovery of bioactive peptides is the study of waste products. This kind of products are normally seen as a problem, for economy and ambient, because they need to be disposed of. They could be better employed, not only as feeding for animals but, for example, as a source of bioactive compounds. Therefore the purpose of this doctoral project was to develop effective analytical strategies for the study of peptides and discovery of bioactive sequences.