Characterization of nanoliposomes containing bioactive peptides obtained from sheep whey hydrolysates

Whey is recognized by the excellent nutritional and functional properties of its proteins, which can be hydrolyzed to peptides with an array of biological activities. In this work, sheep whey was treated with a novel proteinase from Bacillus sp. P7, resulting in hydrolysates with antioxidant and angiotensin-converting enzyme I (ACE-I) inhibitory activity. The hydrolysates were purified by gel filtration chromatography on Sephadex G-25 and the active fractions were subjected to ultrafiltration through 10 kDa cut-off membranes. The fraction enriched in bioactive peptides was encapsulated into phosphatidylcholine liposomes, which were characterized and evaluated by their ability to maintain biological activities. The physicochemical parameters of the liposomes showed constant values during 30 days, with mean diameter around 166 nm and zeta potential 17 mV. Both antioxidant and ACE-I-inhibitory activities were detected in the liposome preparations. In addition, the residual antioxidant activity was 87% after 30 days storage, suggesting the bioactive peptides are stable in this formulation. Liposome encapsulated peptides may offer the possibility of application in areas such as food science and technology, in order to increase the nutritional value and shelf life of food products, as well as for the development of functional foods.