Traditional foods can be functionalized by bioactive peptides either by natural fermentation or ripening and/or by their addition in the form of food ingredients. Milk proteins had been shown as a main source of bioactive peptides. Alpha-casozepine, alpha-s1-CN(f91-100), is a bioactive peptide released by tryptic hydrolysis of bovine alpha-s1-casein that exhibits in vivo anxiolytic activity in three different behavioral tests in rats. The hydrolysate containing this peptide proved effective in clinical studies. In vitro hydrolysis of alpha-casozepine with proteolytic enzymes such as pepsin and chymotrypsin released N-terminal shorter fragment alpha-s1-CN-(f91-97) named heptapeptide that also possesses the same activity. Currently, it has been shown that various Streptococcus thermophilus strains were able to hydrolyze alpha-s1-, alpha-s2- and beta-casein with different efficiency and to release many bioactive peptides but neither alpha-casozepine nor heptapeptide was liberated by the 30 strains of our collection tested. Therefore, to develop a functional food containing such peptides, they could be added directly in dairy products (e.g. fermented milks) and should be resistant to degradation by the proteolytic system of S. thermophilus. The experiments revealed that many bioactive peptides including the heptapeptide were degraded by different S. thermophilus strains even when the strains were lacking the cell surface-associated protease PrtS. Indeed, cell surface-associated aminopeptidase and X-prolyl-dipeptidyl aminopeptidase activities were detected. Therefore, to overcome this problem, we are developing a strategy in which we clone a multicopy of anxiolytic heptapeptide in a plasmid and introduce it into bacteria to produce this peptide as a multimer directly in food product.