Effect of five lactic acid bacteria starter type on angiotensin-I converting enzyme inhibitory activity and emulsifying properties of soy flour sourdoughs with and without wheat bran supplementation

Abstract

The effect of five lactic acid bacteria (LAB), Lactobacillus plantarum, Lactobacillus sanfranciscensis, Lactobacillus brevis, Lactobacillus crustorum and Weissella cibaria on the angiotensin-I converting enzyme (ACE-I) inhibitory activity and emulsifying properties of soy flour enriched with wheat bran sourdough was investigated. Two sourdough were selected based on their ACE-I inhibitory activity: S1 (3% wheat bran) and S2 (0% wheat bran). All LAB strains adequately grew in both sourdoughs, S2 samples registered significantly (P < 0.05) higher total count compared to S1 samples. Only L. plantarum and L. sanfranciscensis fermented sourdoughs exhibited ACE-I inhibitory activity with S2 (S2LP 52.8% and S2LS 40.5%) having higher (P < 0.05) activity than S1 (S1LP 36.5% and S1LS 32.5%). Seventeen amino acids and low molecular weight peptides (0.2–3 kDa) were found in all sourdoughs and their control samples; sourdoughs had higher amino acid levels (P < 0.05) than the control samples. Compared with control samples, sourdoughs exhibited lower emulsifying activity and higher emulsion stability. In conclusion, LAB starter type significantly affected the ACE-I activity and emulsifying properties of soy flour enriched with wheat bran sourdough. L. plantarum and L. sanfranciscensis were the best strains and no wheat bran should be used in soy flour fermented with the two strains.