1. College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China; 2. Key Laboratory of Cold Chain Food Processing and Safety Control, Ministry of Education, Zhengzhou 450001, China
Abstract：During the processing and circulation of frozen meat, freezing stress can induce sublethal injury in harmful microorganisms. These microorganisms are highly likely to resume growth and reproduction during the thawing and processing of frozen meat, thereby posing a potential threat to consumers’ health. This study clarified the formation pattern of sublethal Escherichia coli O157:H7 in pork under freezing stress by a selective plate-counting method. Then, fumigation treatments with six plant-derived antimicrobial agents dissolved in different solvents were screened for their antimicrobial activity against E. coli O157:H7 based on minimum inhibitory concentration (MIC). Furthermore, the impact of plant essential oil fumigation on the repair of sublethally injured E. coli O157:H7 inoculated in thawed pork was investigated. Additionally, the impact on the quality of thawed pork was evaluated by measuring total viable count, pH, color, texture properties, and thiobarbituric acid reactive substances (TBARS) value. The results showed that at –20 ℃, the sublethal rate of E. coli O157:H7 in pork significantly increased with prolonged frozen storage (P < 0.05). Fumigation with oregano essential oil dissolved in propylene glycol or absolute ethyl alcohol exhibited the best inhibitory effect against E. coli O157:H7, with MIC of 625 and 312.5 μL/L, respectively. After thawing pork frozen for 15 d and refrigerating it for 24 h, it was found that sublethally injured E. coli O157:H7 gradually recovered in the propylene glycol-treated group. Compared to the control group (propylene glycol only), oregano essential oil fumigation at 2×, 4×, and 6× MIC reduced the E. coli O157:H7 colony count on selective plates by 0.30, 0.33, and 0.58 (lg (CFU/g)), respectively. This indicates that oregano essential oil fumigation significantly inhibited the recovery of sublethally injured E. coli O157:H7 in thawed pork. Moreover, oregano essential oil fumigation at 6× MIC was able to effectively reduce the total viable count, delay the lipid oxidation, and maintain the pH, color, and texture characteristics of thawed pork.
2026, Vol. 40 
