Microbiota of frozen Vietnamese catfish (Pangasius hypophthalmus) marketed in Belgium

Abstract

Background: Vietnamese catfish (Pangasius hypophthalmus) is highly appreciated in many European countries, the U.S., Canada, Japan etc. This paper presents an overview of the microbiota of frozen Vietnamese catfish products marketed in Belgium. Samples of Pangasius steaks, portions and fillets from six brands were collected from supermarkets located in Ghent, Belgium. Results: The total psychrotrophic and mesophilic aerobic counts of the samples evaluated from each brand did not differ significantly (p > 0.05) and ranged from 3.8-5.2 log CFU/g and 3.8-4.8 log CFU/g, respectively. Lactic acid bacteria counts varied from 2.2 to 4.1 log CFU/g while the counts of presumptive Enterobacteriaceae ranged from 1.6 to 3.8 log CFU/g. A total of 132 isolates were collected from the plates used to enumerate the microbial parameters mentioned above. Fourteen different genera and 18 different species were identified by means of 16S rRNA gene sequencing. The most prevalent genera of Lactococcus (31.2 %), Staphylococcus (11.7 %), Serratia (10.4 %),Acinetobacter (9.1 %), Enterococcus (7.8 %) and Pseudomonas spp. (6.5 %) were identified by means of 16S rRNA gene sequencing. Conclusion: The results obtained provide an overview of the dominant microbiota on frozen Pangasius which is useful for the development of appropriate preservation techniques for thawed Pangasius products.