Protective effects of soybean protein and egg white protein on the antibacterial activity of nisin in the presence of trypsin

- Exogenous trypsin could affect the antibacterial activity of nisin by enzymolysis.
- Soybean protein and egg white protein contain trypsin inhibitor.
- Soybean protein and egg white protein could inhibit the activity of trypsin.
- Trypsin inhibitors in two proteins could protect the activity of nisin.
- The protections were also in cooked meat product.

The using of nisin to prevent foodborne pathogens (Staphylococcus aureus and Listeria monocytogenes) from contamination has received broad attentions during meat processing. However, the application of nisin has been limited because its antibacterial activity may be inhibited by trypsin. In this study, the protective effects of soybean protein and egg white protein on antibacterial activity of nisin were evaluated. It could be concluded that exogenous trypsin decreased the antibacterial activity of nisin, soybean protein and egg white protein could keep the nisin activity from enzymolysis of trypsin. Trypsin inhibitors in soybean protein and egg white protein could protect the antibacterial activity of nisin. Nisin with soybean protein or egg white protein in cooked meat product presented better quality preservation effects than nisin alone in the presence of trypsin. The total viable counts (TVC) and total volatile basic nitrogen (TVB-N) of nisin-treated group were significantly higher than these in nisin-soybean protein-treated and nisin-egg white protein-treated groups with trypsin. This study showed the potential of using soybean protein and egg white protein to stabilize the antibacterial activity of nisin under high trypsin conditions.