Microbiological evaluation of fish

Abstract

Fish meat has a specific composition that positively influences human health. Thanks to this composition, it is an excellent nutritional medium for growth and reproduction of undesirable microorganisms, which may cause spoilage and they can also lead to alimentary illnesses. Microbiota of fish is dominated by Gram negative and psychrophilic bacteria. Microbial contamination causes fish deterioration and leads to the end of its shelf-life when reaches levels between 107 and 109 CFU.g-1. The most appropriate temperature for storage of fish is between -1 °C and 4 °C and the ideal relative air humidity is 80 to 85%. The objective of the work was to evaluate microbiological quality of fresh fish (Rainbow Trout, Atlantic Salmon, Atlantic Cod) bought in various types of stores in the Czech Republic and to evaluate if different storage temperatures have influence on the quantity of microorganisms. The following microorganisms were monitored: the total aerobic count (TAC), coliform bacteria, E. coli, Salmonella spp. and Vibrio parahaemolyticus. Based on the obtained results it is possible to state that difference between individual stores (p >0.05) in the total aerobic count and the quantity of E. coli (except for cod) was not proven. After 2 days of storage there was increase (p ˂0.05) of the total aerobic count in case of all monitored fish species from all stores. In case of coliform bacteria and E. coli there was increase (p ˂0.05) of their quantity in a majority of the analysed samples. Different storage temperature (4 °C and 8 °C) did not have influence (p ˂0.05) on the TAC, the quantity of coliform bacteria (except for cod) and the quantity of E. coli (except for trout).