Enhancing the sporicidal activity of high pressure processing by combination with moderate temperature and the peptide mixture LK

Bacterial spores inactivated incompleteness is the most difficult issue of high pressure processing (HPP) sterilization. This study initially demonstrated the effect of moderate pressure at 200 MPa combined with moderate temperature at 80 °C and the random antimicrobial peptide mixtures LK at 100 μg/mL for 15 min (PT-LK) on spore inactivation. PT-LK demonstrated a broad-spectrum bactericidal effect on various spore-forming bacteria, in addition to a pronounced spore inactivation effect across diverse foods. Furthermore, the morphological results showed that the spores displayed blast-like openings on surface. LK was found to enter the spore core and destroy the core area. Subsequently, the stability of LK under 200 MPa and 80 °C was investigated. High-performance liquid chromatography (HPLC) analyses indicated that processing at 200 MPa and 80 °C did not significantly impact the stability of LK. Moreover, under the conditions of 200 MPa and 80 °C were found to enhance the binding affinity between LK and the spore coat protein CotE, thereby enhancing its biological activity. Finally, the biosafety profile of LK was evaluated. In vitro cytotoxicity was evaluated using RAW264.7 macrophages, while antimicrobial activity was assessed against beneficial gut bacteria. The results demonstrated that LK at a concentration of 100 μg/mL exhibited no significant cytotoxic effects and negligible antibacterial activity against beneficial gut bacteria. Above all, this research provides new insights that advance the understanding of HPP as a mild processing technology and support its potential for food sterilization applications.