Characterization of Proteolytic Activity of Artichoke (Cynara scolymus L.) Flower Extracts on Bovine Casein to Obtain Bioactive Peptides

SIMPLE SUMMARY: Recently, dairy proteins, in addition to their basic nutritional role in the diet, were recognized as a source of bioactive peptides. Such peptides are encoded within the primary structure of the protein and can be released by enzymatic hydrolysis. The growing interest in the development of functional foods for the benefit of consumer health led to a recent increase in research on the production of bioactive peptides from different matrices and production methods. The use of aspartic proteases from stigmas of mature artichoke (Cynara scolymus L.) flowers to obtain hydrolytic enzymes (cinarases) in the production of bioactive peptides would involve the utilization of an agricultural residue of a plant species of great socio-economic importance. In the present study, the characterization of the optimal hydrolysis conditions of artichoke flower extracts was carried out for the production of peptides from bovine casein. Furthermore, the angiotensin-converting enzyme-I inhibitory activity and the antioxidant capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) free radicals in vitro were determined for the obtained hydrolysates. The results revealed that the water-soluble extract of artichoke flower could be suitable for the production of bioactive peptides from whole bovine casein. ABSTRACT: The aim of this work is to establish the most suitable proteolysis conditions to obtain bovine casein hydrolysates containing peptides with antioxidant and antihypertensive capacity. To this end, the proteolytic activity of Cynara scolymus L. flower extracts was characterized on whole bovine casein, evaluating the effect of several factors (pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time). The optimal conditions to carry out the hydrolysis with the C. scolymus L. extract were as follows: pH 6.2, 50 °C, and 0.023 mg·mL(−1) of extract-protein concentration. A Michaelis constant (K(m)) value of 5.66 mg·mL(−1) and a maximum rate of reaction (V(max)) of 8.47 mUAbs∙min(−1) were observed. The optimal hydrolysis time was 17 h. The casein hydrolysates obtained with these conditions contained peptides with antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity: 30.89%; Trolox equivalent antioxidant capacity (TEAC) against 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free radical (ABTS(●+)): 4.43 mM Trolox equivalent·mg(−1) peptide) and antihypertensive activity, showing 55.05% angiotensin-converting enzyme-I inhibition in vitro.