Dynamic digestion of a high protein beverage based on amaranth: Structural changes and antihypertensive activity

An amaranth beverage (AB) was subjected to a simulated process of dynamic gastrointestinal digestion DIDGI®, a simple two-compartment in vitro dynamic gastrointestinal digestion system. The structural changes caused to the proteins during digestion and the digesta inhibitory capacity of the angiotensin converting enzyme (ACE) were investigated. In gastric compartment the degree of hydrolysis (DH) was 14.7 ± 1.5 % and in the intestinal compartment, proteins were digests in a greater extent (DH = 60.6 ± 8.4 %). Protein aggregation was detected during the gastric phase. The final digesta obtained both at the gastric and intestinal level, showed ACE inhibitory capacity (IC₅₀ 80 ± 10 and 140 ± 20 μg/mL, respectively). Purified fractions from these digesta showed even greater inhibitory capacity, being eluted 2 (E2) the most active fraction (IC₅₀ 60 ± 10 μg/mL). Twenty-six peptide sequences were identified. Six of them, with potential antihypertensive capacity, belong to A. hypochondriacus, 3 agglutinins and 3 encrypted sequences in the 11S globulin. Results obtained provide new and useful information on peptides released from the digestion of an amaranth based beverage and its ACE bioactivity.