ABSTRACT
Instituto Português do Mar e da Atmosfera (IPMA), Av. Brasília, 1449-006 Lisbon, Portugal. Emails: cpires@ipma.pt; irineu@ipma.pt
* Corresponding author
Protein hydrolysates have gained increasing importance as food ingredients. Their unique properties differ from intact proteins because of enzymatic hydrolysis. As proteins, the functional properties of protein hydrolysates are related to their molecular size, quantum of reacting amino acid residues, distribution of electrostatic charges, hydrophilicity and hydrophobicity, and carbohydrate and mineral interaction. However, they are also affected by the physicochemical properties of the parent protein used as substrate, the specifi city of the protease, the hydrolysis conditions (temperature, pressure, pH, ionic strength, water activity, and solvent polarity), the reaction time, and the combined treatment (enzymatic hydrolysis combined with another enzymic or nonenzymic modifi cation). In fact, as referred by Mahmoud (1994), the peptide hydrolysis lead to an increase in hydrophilicity and net charge, a decrease in molecular size and a change in the molecular structure of the parent protein. However, the functional properties of protein hydrolysates is much more complex as their ability to interact with other constituents in a food formulation depends on the composition and processing parameters employed in food manufacturing.
