The high processing resistance of spores formed by Clostridium botulinum and its surrogate C. sporogenes PA 3679, presents a major challenge to food safety of low-acid foods. This study investigated the inactivation of C. sporogenes spores in carrot puree by pressure-assisted thermal processing (PATP; 600 MPa, 105 °C, 10 min), applied alone or in combination with cationic antimicrobials: chitosan (10 mg/mL), epsilon polylysine (0.2 mg/mL), and lauric arginate (0.2 mg/mL), followed by microbial stability evaluation during storage at 23 °C for 35 days. Additionally, spore response in HEPES buffer was evaluated after pressure-only (600 MPa, 27 °C, 10 min) and PATP treatment. Survivors were enumerated by the 3-tube most probable number method. PATP treatment resulted in a 4-log reduction of spores in carrot puree but allowed a 1-log increase during storage. Adding chitosan achieved a 6.5-log reduction, while incorporation of epsilon polylysine or lauric arginate achieved >6.5-log reduction, maintaining the spore population below detection levels (<0.48 Log MPN/ml) throughout storage. In buffer, pressure-only treatment was ineffective, whereas PATP yielded a 5.7-log reduction without recovery, highlighting nutrient availability as one critical factor in post-treatment spore recovery. Zeta potential results revealed that PATP increased surface charge of both the antimicrobials and spores, suggesting electrostatic interactions that may lead to spore death. The study demonstrates that PATP, in combination with these cationic antimicrobials, acts as an effective hurdle, providing both sporicidal activity during treatment and sporostatic effects during storage, thereby enhancing the safety and shelf-stability of a low-acid food like carrot puree. • PATP (600 MPa, 105 °C, 10 min) inactivated C. sporogenes PA 3679 spores. • Combined with cationic antimicrobials, PATP showed strong sporocidal effects. • Carrot puree stayed stable for 35 days at 23 °C after PATP and antimicrobial use. • Zeta potential shifts were linked to the extent of spore inactivation. • PATP with antimicrobials offers an effective hurdle against bacterial spores.
Astorga-Oquendo et al. (Wed,) studied this question.