Fish is an excellent source of protein and other essential minerals and vitamins; nevertheless, several food-borne disease outbreaks have been linked to the consumption of different types of fish. Therefore, we aimed to overcome these health threats by evaluating gamma radiation as a good fish preservation method. The aerobic plate count (APC), identification of most common pathogenic bacteria, organoleptic properties, proximate composition, and other chemical evaluations were detected in both untreated and gamma-treated fish. The overall grades of organoleptic evaluations ranged from good to very good. Fortunately, the overall chemical analysis of all examined fish samples was accepted. For the untreated fish samples, the APC was within and above the permissible limit (5 × 10⁷ CFU/g). Pathogenic bacteria were detected with a high prevalence rate, especially S. aureus, which was found in high percentages among examined untreated fish samples. Regarding the treated fish samples, APC and pathogenic bacterial counts were reduced in a dose-dependent manner, and the irradiation at dose 5 KGy resulted in complete eradication of the aerobic plate count (not detectable) with a mean reduction percentage equal to 100%. However, gamma irradiation has no significant effect on proximate composition; particularly, carbohydrates, proteins, and lipids were not significantly affected by low and medium doses of radiation. Therefore, gamma irradiation is a highly effective fish preservation method without any effect on fish quality. Additionally, gamma irradiation as a cold process is an attractive technology for solving the problem arising from fish-borne pathogens, and it has been purposed in this study as a cheap and safe method for reducing microbial contamination of fish.

This study was conducted to determine the residual concentrations of lead (Pb), cadmium (Cd), mercury (Hg) and Arsenic (As) in Claris gariepinus from Abou Hammad, Zagazig and Faqous fish markets at Sharkia Governorate, Egypt, to assess such metals dietary intake, and to evaluate the possible health risks linked with the fish consumption. Therefore, ninety Claris gariepinus samples, 30 of each, from Abou Hammad, Zagazig and Faqous fish markets were analyzed using atomic absorption spectrophotometer (AAS). The obtained results showed that, the mean residual concentrations in Clarias gariepinusfrom Abou Hammad, Zagazig and Faqous fish markets were 0.08±0.02, 0.19±0.02 and 0.4±0.06 ppm for Cd, respectively. While, the results of Pb were 0.45±0.07, 0.42±0.04 and 0.51±0.08 ppm, respectively; 0.59±0.15, 1.02±0.08 and 0.15±0.03 ppm for Hg, and 0.74±0.06, 0.69±0.04 and 0.64±0.08 ppm for As. The estimated metals' concentration exceeded the recommended safety limits outlined by Egyptian standards (ES No 7136/2010) for most samples. The total estimated daily intakes (EDI) of Cd, Pb, Hg and As were 1, 3.57, 0.57and 2.14 μg/kg BW/day, respectively, that were less than the tolerable daily intake (TDI) suggested by the Joint Expert Committee on Food Additives (JECFA). Referring to the potential health risks of inspected Claris gariepinus, it was valued that the target hazard quotient (THQ) of As of all Claris gariepinus samples from Abou Hammad, Zagazig and Faqous fish markets were 1.34, 1.25, 1.16, respectively. These results were more than 1, representing possible health risks, while THQs of other metals (Pb, Cd, Hg) from Claris gariepinus consumption from all examined areas were lower than 1 as compared to the reference doses. The obtained results give us an alert that the consumer could be under health hazards so that further investigation of Claris gariepinus is recommended at Sharkia Governorate.