Validation of γ-irradiation in controlling microorganisms in fish

Abstract

Purpose – With a previous throughput of sea fish contamination with microorganisms, the present study extended the array of such spoilage over four other fish samples including Pseudapocryptes elongates, Scomberomorus cavalla, Xenentodon cancila and Otolithoides pama, evaluated the reductive impact of irradiation, and further validated the irradiation methodology in controlling the microbial quality of the sea fish samples. The paper aims to discuss these issues. Design/methodology/approach – Twelve samples of each sea fish were collected from super shops in Dhaka city and a portion of each sample was subjected to γ-irradiation at a dose of 3 kilo gray (kGy). Then, both non-irradiated and irradiated samples were tested for the presence of pathogenic bacteria though culture on different specific media followed by biochemical identification. Drug resistance among the pathogens was also investigated. Findings – Most of the non-irradiated samples were observed to harbor huge bacteria and fungi (1.3×102-1.5×107 cfu/g or cfu/ml) including the fecal coliforms ranging up to 105 cfu/g or cfu/ml, leading to an elevated threat to public health. Besides, the isolates were found to be resistant against single or multiple antibiotics, which further brought treatment complications during the possible disease outbreaks. However, the pathogenic load was significantly reduced after applying 3 kGy dose of γ-irradiation on the samples in consistent to the previous work using different fish samples. Research limitations/implications – A similar type of work has already been published by the group using different samples this year in the Journal of Microbiology, Biotechnology and Food Sciences, Vol. 2 No. 4, pp. 2420-2430. However, even being an increment of the previous work, the present work deals with extended array of sea fish samples with an objective of controlling food safety. Practical implications – The present work further confirms and assists the knowledge of food protection and the identification of spoiling bacteria and fungi by applying replicable methods projects of the novelty and practical outcome of the work. Originality/value – The reduction of pathogenic load revealed the efficacy of γ-irradiation as a mean of preserving fish quality. Besides, the study quantified the contaminating microorganisms as well as identified the drug-resistant bacteria among sea fish samples. Traditional but standard cultural and biochemical tests, demonstration of drug resistance among the isolated microorganisms from fish samples and finally the microbial elimination by irradiation might contribute to the existing knowledge on major sea fish.