Study on the preparation of ACE inhibitory peptides by probiotic fermentation of quinoa

Abstract

Objective: The potential ability of probiotics to prepare angiotensin-converting enzyme （ACE） inhibitory fermentation broth from quinoa and the effects of fermentation process on it were investigated. Methods: In this study, 18 strains of lactic acid bacteria and 12 strains of yeast were screened for their ability to prepare ACE inhibitory fermentation broth using quinoa as the raw material and the ACE inhibition rate as an indicator. The inoculum amount, fermentation temperature and fermentation time were optimized by orthogonal tests. Finally, the peptides in the fermentation broth were identified, and the selected peptides were tested in vivo to evaluate the antihypertensive effect. Results: Lactobacillus paracasei L2 had the best effect among the 30 strains, and the ACE inhibition rate of the fermentation broth prepared by fermenting quinoa was as high as （86.50±0.25）%; The optimal fermentation conditions for the preparation of ACE inhibitory fermentation broth by fermenting quinoa with Lactobacillus paracasei L2 strain were 5% inoculum, 48 h fermentation time, and 34 ℃ fermentation temperature. Under these conditions, the ACE inhibition rate was the highest, which was （90.41±0.16）%; By comparing the results of liquid quality identification with the database, two peptides NIFRPFAPEL and AALEAPRILNL with better ACE inhibition effect were obtained. Both NIFRPFAPEL and AALEAPRILNL could significantly lower blood pressure in spontaneously hypertensive rats （SHR）, and both achieved the best blood pressure lowering effect at 6 h after gavage. Systolic blood pressure （SBP） decreased by （2.67±0.21） and （3.46±0.01） kPa, and diastolic blood pressure （DBP） decreased by （29.36±0.54） and （22.33±0.77） kPa, respectively. And NIFRPFAPEL and AALEAPRI-LNL had no effect on blood pressure in Wistar-Kyoto rats （WKY）. Conclusion: Therefore, quinoa is a high-quality grain raw material for preparing ACE inhibitory fermentation broth, and NIFRPFAPEL and AALEAPRILNL can be used for the development of blood pressure-lowering functional foods or medicines.

Keywords

• probiotic
• hypertension
• quinoa
• ace inhibitory peptide
• process optimization
• in vivo test