الفهرس 
Introduction
Health benefit of tuna fishOnly 14 pages are availabe for public view
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Abstract
A total number of45 samples of canned tuna from 3 brands (15 of each brand) in this study were collected from popular supermarkets at Assuit city to be sensory evaluated and analyzed for heavy metal content namely: mercury, cadmium, lead and aluminum.
Sensory examination of the samples had done by nine point hedonic scale, statistical analytical results in the different 3 brands of canned tuna revealed that the overall means for all the four attributes (colour, odor, flavor and all over acceptability) ranged from 7.65 to 8.22 These values demonstrated that the preference was more pronounced towards the canned tuna of brand C, followed by brand A then brand B.
Statistical analytical results of mercury levels in different brands of canned tuna revealed that as mean ± standard error(ppm) were 3.78 ± 0.94 for brand A, 3.71± 0.94 for brand B and 4.03 ± 77 for brand C.
Statistical analytical results of cadmium levels in different brands of canned tuna revealed that as mean ± standard error (ppm) were 0.34 ± 0.12 for brand A, 0.18 ±0.06 for brand B and 0.24 ± 0.04 for brand C.
Statistical analytical results of lead levels in different brands of canned tuna revealed that as mean ± standard error (ppm) were 1.94 ± 0.13 for brand A, 1.48 ± 0.14 for brand B and 1.58 ± 0.16 for brand C.
Statistical analytical results of aluminum levels in different brands of canned tuna revealed that as mean ± standard error (ppm) were 5.27 ± 0.51 for brand A, 0.34 ± 0.14 for brand B and 10.22 ± 1.78 for brand C.
The comparison between the obtained analytical results and the standard limit showed for mercury all the samplesexceeded the permissible limit (0.2 ppm) of Egyptian standard (ES, 2010). Two samples (4.4%) were within the safe level of mercury in fish (1 ppm) set by EC, 2006, While 43 samples (95.5%) were over the permissible limit. But one sample (2.2%) was within the permissible limit (0.5ppm) that was set by the US Environmental Protection Agency(Salaramoli et al., 2012) and 44 samples (97.8%) were over the permissible limit.
For cadmium, 38 samples (84.4 %) were below the highest limit for this metal in fish (0.5 mg/kg) recommended by FAO (1983) and 7 samples (15.5 %) were over this limit. According to highest limit of cadmium in fish (0.05 mg/kg) that was set byEgyptian standard (ES, 2010) andEC (2001) 16 samples (35.5%) were below the limit and 29 samples (64.4%) were over than this limit.
For lead all samples were above the maximum lead level permitted for canned fishes (0.2 mg/kg) according to the Turkish Food Codex (Anonymous, 2002), European Communities (Commission of the European Communities, 2001) and (0.1 mg/kg) Egyptian standard (ES,2010).
It was reported that maximum aluminum levels in some food samples were 15 mg/kg (Demirel et al., 2008).Two samples was above this level (16 mg/kg) and the remaining samples ranged from ND to 14.8 mg/kg.
By comparing between the three brands in the concentration of heavy metals, brand B contained the lowest mean of mercury, cadmium, lead and aluminum.
There is a significant difference between brand A, B and C in mean values of mercury, cadmium, lead and aluminum.
The source of environmental contamination by such estimated trace elements were discussed, where sources of contamination should be avoided or reduced as possible from human diets.