Changes in the morphology of catfish infected by Edwardsiella tarda as indicator of food safety

Abstract

Edwardsiella tarda is a pathogenic bacterium in catfish. The aim of the research was to observe the morphological changes of catfish infected by Edwardisella tarda as catfish safe consumption indicator. Catfish was artificially infected with Edwardsiella tarda in aquarium for 7 days. The observation included catfish behavior, organoleptic freshness, meat morphology and the number of Edwardsiella tarda found in catfish skin, meat as well as in aquarium water. At the end of culture, it was known that the number of Edwardsiella tarda in meat, skin and water were 105 cfu/g, 108cfu/g and 102 cfu/mL. The fishy smell in aquarium could be sensed starting from day 3 after the pathogen introduction which was in concomitant with appearing red spots in the catfish skin. The freshness of catfish based on organoleptic tests was still around 9-7. From the SEM photographs showed the change in the structure of catfish meat. Histology observation showed the myofibril fragility increased. It recommended for consumers to keep on eye in appearance of red the spots color on catfish skin since it was visible indicator of early stage of spoilage caused by pathogen.