Control of Bacterial Contamination during Marine Fish Processing

Abstract

Fish is a vital source of nutrients to humans due to its proteinaceous nature, high content of unsaturated fatty acids and low contents of carbohydrates. Fish consumption therefore is recommended to circumvent lifestyle diseases associated with the consumption of red meat. In their natural environments fish are exposed to a myriad of microorganisms some of which compromise the shelf life of the product and/or safety in humans. Most fish factories are located along coasts hence find it economical to make use of processed sea water in processing. Processed sea water however can be a source of microbial contamination to fish. Prudent quality assurance regimes are therefore required to minimise low fish quality products and promote consumer safety. Fish factories are also vulnerable to biofilm formation on surfaces and within water distribution pipes. Biofilms result from bacterial attachment and growth in aqueous environments within which pathogenic and spoilage bacteria become resistant to cleaning and sanitising agents. Biofilms defy efforts directed at maximising the safety and quality of fish. This article reviews the conditions permissible to bacterial contamination in marine fish factories. The role of water in bacterial contamination and survival has been highlighted. Bacterial pathogens commonly associated with fish factories and their survival strategies have also been discussed. The use of a number of selected oxidising agents and UV irradiation as sanitizers in marine fish processing have been explored. The fundamental antimicrobial mechanisms of chlorine, ozone and H₂O₂ is the generation of toxic metabolic intermediates that damage microbial structural components, enzymes and cell membranes causing metabolic paralysis and leakage of cytoplasmic contents and cell death. UV radiation damages DNA and hinders gene expression processes. Controlling bacteria biofilm by means of sanitising agents has been well experimented in fresh water systems, but knowledge about disinfection of marine waters is still lacking. The review concludes that in order to optimise the microbiological quality of marine fish, suitable disinfectants effective in sea water need to be explored and authenticated. It is therefore necessary to conduct cost/benefit studies of sanitising agent agents that are effective in sea water and their impact on the quality and safety of marine fish.

Key words: Biofilms Factories Sanitation Seafood.