Distribution of cold-resistant bacteria in quick-frozen dumpling and its inhibition by different antibacterial agents

The cold-resistant bacteria resident in quick-frozen dumpling were systematically analyzed to estimate the microbial contamination. The results showed thatPseudomonasandStenotrophomonaswere the main microbial sources. Among them,Stenotrophomonas maltophiliawas a common environmental or clinical opportunistic pathogen. Therefore, this study further investigated the characteristics ofS. maltophilia4-1, and five bacteriostatic agents were used to inhibit the strain.S. maltophilia4-1 could tolerate a certain salt concentration and was suitable for growth in a neutral or weakly alkaline environment. Its optimum growth temperature ranges from 28 to 37 degrees C. The antibacterial tests suggested that chloramphenicol had the best antibacterial effect onS. maltophilia4-1, and acetic acid could inhibitS. maltophilia4-1 by providing an acidic environment. Tea polyphenol also had inhibitory effect onS. maltophilia4-1 with MIC value of 1.25 mg/ml, which was expected to be a natural antibacterial agent for the control ofS. maltophilia. Practical applications There are few studies on the safety of quick-frozen dumplings. This study focused on quick-frozen dumpling and revealed the distribution of low-temperature microorganisms, providing a reference for understanding the safety of quick-frozen foods and indicating the direction of targeted control of microbial contamination. Tea polyphenols exhibited a good antibacterial effect onS. maltophilia, which demonstrated the potential of natural products in inhibiting food-borne bacteria. This finding laid a theoretical foundation for the application of natural bacteriostatic agents in foods.