Bacteria-triggered on-demand thymol release for salmon preservation: A self-destructive antibacterial strategy

To prevent foodborne pathogen invasion in fresh meat during storage, this study develops an enzyme/redox dual-responsive nanomaterial (Thy@MSN-S-S-Casein). Upon encountering bacteria, the casein shell is degraded by bacterial proteases, and glutathione (GSH) cleaves the disulfide bonds on the mesoporous silica nanoparticle (MSN) surface, releasing thymol to combat the bacteria. Trypsin and GSH triggered a cumulative release of 68.37 % thymol from Thy@MSN-S-S-Casein within 48 h, which was significantly higher than the release by trypsin alone (49.93 %) or without any activation (17.33 %). The antibacterial activities of Thy@MSN-S-S-Casein can be triggered by both artificially inoculated bacteria and naturally-infected bacteria on the salmon surfaces, leading to a reduction in the total viable count (TVC) in both experiments. Additionally, it inhibited the deterioration of the salmon fillets' quality indicators and extended their shelf life by about 3 days. This bacteria-triggered release strategy offers a promising self-destructive antibacterial approach for mitigating pathogen outbreaks in food preservation.