Enzymatic hydrolysis of whey proteins is a feasible alternative
to modify and improve functional properties of this sub-product of
the dairy industry, thus providing different biologically active
peptides [1]. Particularly, the removal of phenylalanine (Phe) is
an essential step to produce a source of proteins for the dietary
management of phenylketonuria (PKU) patients, who demand
controlled quantities of this amino acid in their diet [2].
Phenylketonuria (PKU) is a disease of recessive autosomic
inheritance, characterized by a deficiency in the system of Phe
hydroxylation, caused by the absence or reduction of the activity of
the hepatic enzyme phenylalanine hydroxylase, responsible for the
conversion of Phe into tyrosine. High levels of Phe in the blood, and
the associated tyrosine deficiency, will cause mental retard, which
can be avoided using a controlled diet [3]. In most cases, the intake
by the infant should be reduced to 50–70 mg/(kgbody weight day).
From 7 years old to adulthood this rate should be reduced to 10–
40 mg/(kgbody weight day) [2,4].
Commercial protein hydrolysates for PKU patients are usually a
pool of amino acids, without Phe. This product is obtained after
chemical hydrolysis of some protein source, followed by proper
downstream processing. However, the presence of other aromatic