β-lactoglobulin (βLg) is an important source of angiotensin I-converting enzyme (ACE) inhibitory peptides. These peptides have the potential to become ingredients in future functional foods, however appropriate technologies are needed for their cost-effective industrial production. Thus, this work was carried out to investigate the feasibility of an ion exchange process for the production of potent βLg-derived ACE inhibitors using Protease N Amano, a commercial food-grade proteolytic preparation. βLg was hydrolysed in solution and in situ using Protease N Amano and optimal hydrolysis conditions.