Abstract: In order to study the changes of antimicrobial peptides during processing and storage, Staphylococcus aureus and Escherichia coli were used as indicator bacteria in the experiment. The relative antibacterial activity stability of antimicrobial peptides was evaluated from the aspects of minimum inhibitory concentration (MIC), temperature, pH, different concentrations of metal ions, and storage time. The results showed that antimicrobial peptides had broad-spectrum antibacterial activity, good thermal stability, and could maintain relative inhibition rates of 88.16% and 93.88% after 30 minutes of treatment at 100 ℃; different pH values had a significant impact on the antibacterial activity of antimicrobial peptides (P<0.05). Antimicrobial peptides exhibited significantly higher antibacterial activity in acidic environments than in strongly alkaline environments, indicating that antimicrobial peptides were more suitable for processing and production in acidic environments. Different concentrations of Ca²⁺ and Na⁺ in the solution had significant effects on the antibacterial activity of antimicrobial peptides. High salt environments could cause a decrease in antimicrobial activity of antimicrobial peptides, but the lowest relative inhibition rate was still above 80%. The effect of storage time on the relative inhibition rate of Escherichia coli was greater than that of Staphylococcus aureus, and the relative inhibition rate remained above 85% after 12 months of storage.

Key words: antimicrobial peptides, Staphylococcus aureus, Escherichia coli, antibacterial activity, stability