In vitro antioxidant and angiotensin I-converting enzyme inhibitory properties of enzymatically hydrolyzed quinoa (Chenopodium quinoa) and kiwicha (Amaranthus caudatus) proteins

Background and objectives: This study investigated the in vitro antioxidant and angiotensin I-converting enzyme (ACE-I) inhibitory properties of quinoa (QPH) and kiwicha (KPH) protein hydrolysates. Findings: Enzymatic treatments with Neutrase for 120 min for quinoa and sequential Alcalase-Neutrase hydrolysis for 240 min for kiwicha protein, both at 50°C, presented high antioxidant activities and ACE-I inhibition (1.50 and 1.67 μmol TE/mg of protein and 89.2 and 72.8%, respectively) and the lowest IC₅₀ values (0.08 and 0.29 mg/ml, respectively). After simulated gastrointestinal digestion (pepsin–pancreatin), both protein hydrolysates did not display significant changes in their antioxidant and ACE-I inhibition properties. Conclusions: The in vitro antioxidant and antihypertensive properties (ACE-I inhibition) of QPH and KPH obtained via enzymatic hydrolysis using food-grade commercial enzymes were demonstrated. In addition, tested in vitro bioactive properties did not change after simulated gastrointestinal digestion. Significance and novelty: The results of this research might be used to obtain QPH and KPH with bioactive properties and/or as starting material for subsequent processes of separation and purification to obtain bioactive peptides.