Abstract: In this work, we conducted a kinetic study on the mixed culture fermentation of bovine bone meal with Bacillus cereus MBL13-U, which was isolated in our previous study, Streptococcus thermophilus and Lactobacillus plantarum for preparing angiotensin converting enzyme (ACE) inhibitory peptides. Kinetic models with a determination coefficient greater than 0.97 for cell growth, product formation and substrate consumption were developed through nonlinear fitting using Logistic equation and Luecleking-Piret equation. The model predictions were in good agreement with the measured values. The structural properties of the ACE inhibitory peptides were characterized by scanning electron microscopy (SEM), ultraviolet (UV) spectroscopy and differential scanning calorimetry (DSC). The results showed that gully marks appeared on the surface of bovine bone-derived ACE inhibitory peptides, because they had a strong moisture absorption capacity with the maximum absorption at 222 nm as collagen-derived peptides do. Besides, the ACE inhibitory peptides had an increased thermal denaturation temperature and a better thermal stability than bovine bone collagen, apart from good solubility, acid and alkali resistance, and their salt tolerance was strong when the NaCl concentration was below 0.9 mol/L. Pepsin and trypsin had slight effects on bovine bone ACE inhibitory peptides.

Key words: Bacillus cereus MBL13-U, angiotensin converting enzyme (ACE) inhibitory peptides, fermentation kinetic models, structure characterization, characteristics