Effect of ultrasonication pretreatment followed by enzymatic hydrolysis of caprine milk proteins and on antioxidant and angiotensin converting enzyme (ACE) inhibitory activity of peptides thus produced

The effect of ultrasonic pretreatment followed by enzymatic hydrolysis was studied to assess the bioactivity of caprine milk protein. Ultrasonication process was optimised with respect to pH (8.5), ultrasonication time (20 min), and amplitude (80%). The results indicated that the pretreatment process enhanced the soluble protein concentration from 4.35 +/- 0.02 mg mL(-1) to 6.15 +/- 0.02 mg mL(-1) under optimal conditions. RP-UHPLC fractionation of protein hydrolysates produced four fractions of peptides from neutral protease and pepsin. The highest antioxidant activity of 53.21% (IC50 = 1.34 mg mL(-1)) and 68.9% (IC50 = 0.402 mg mL(-1)) inhibition of DPPH was obtained with the third fraction for both neutral protease (F3: EPr) and pepsin (F3: EPe). The same fraction showed the highest ACE-inhibitory effect for neutral protease (40.09%, IC50 = 2.14 mg mL(-1)) and pepsin (67.02%, IC50 = 0.415 mg mL(-1)). (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The combination of ultrasonic pretreatment and enzymatic hydrolysis showed positive effects on the bioactivity of caprine milk protein, increasing soluble protein concentration and generating peptides with antioxidant and ACE-inhibitory activities.