Authors: Thao T. H. Nguyen, Achyut Adhikari, Debanjana Bhattacharya,
Vijay S. Chhetri, Karuna Kharel
Fish processing environment is very favorable for the growth of microorganisms and highlights a potential risk associated with microbial hazards. The present study investigated the growth behavior of aerobic bacteria, yeasts and molds, and bacterial pathogens or surrogate (Listeria monocytogenes and Clostridium sporogenes) on thawed and fresh catfish fillets during refrigerated storage (5°C – 7°C). Thawed and fresh fillets were respectively inoculated with L. monocytogenes and C. sporogenes, and packaged in LDPE bags. In uninoculated catfish, the populations of aerobic bacteria, and yeasts and molds increased significantly (P < 0.05) after 24 h of storage. The acceptable microbial limit was exceeded by aerobic bacteria (7.446 log CFU/g) after 4 days, and yeasts and molds (2.97 log CFU/g) after 3 days of refrigerated storage. Listeria population increased by 1.51 log CFU/g on thawed catfish after 6 days of storage. However, there was no significant increase in growth of C. sporogenes vegetative cells on fresh catfish fillets. These results indicated that the microbiological quality of refrigerated thawed catfish would become unacceptable within 3 – 4 days. Our results also implied that environmental pathogens such as L. monocytogenes and Clostridium sp. can survive on catfish fillets for extended periods during refrigerated storage. Proper sanitation and hygienic practices are essential to control microbial hazards during handling and processing of catfish fillets.
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