Effects of pH, Temperature, Storage Time, and Protective Agents on Nisin Antibacterial Stability

Nisin as a kind of bacteriocin and peptides can inhibit the growth of gram-positive bacteria effectively, which is easily influenced by heat, alkali, and storage time significantly. In this study, it is concluded that adding substances such as chitosan, ascorbic acid, tyrosine, and FeSO4 do well in the enhancement of nisin antibacterial stability. The protective agents have been proposed to improve stability and long-term effectiveness of nisin. Above all chitosan was of great efficiency, followed by FeSO4 and tyrosine, but ascorbic acid was better in acidic conditions. Similar phenomenon occurred when nisin was at elevated pH and high temperature. At pH 6.0, room temperature, nisin titer got rise to 154.7 IU/mL after added chitosan compared to the original 105.6 IU/mL, and even after the 121 degrees C heating for 20 min, the titer was 2.8 times higher than control.