الفهرس 
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Abstract
The present investigation was conducted to evaluate the physico-chemical, microbiological and organoleptic characteristics of tuna (Thunnus thynnus) and common carp (Cyprinus carpio) products during frozen storage condition. Tuna and carp products of burger, nuggets and fingers were prepared and stored at -18°C for six months. The above-mentioned characteristics were measured at zero time and every two months as a time interval during the storage period. The results indicated that the moisture content significantly decreased over the storage time for (3.11±0.83 g every two months). As a result, at the end of storage time (6 months), the loosing ratios in moisture content for burger, nuggets and fingers were 15.87, 16.03 and 15.84 (%), respectively. Heavy metals content in tuna and carp were arranged in a descending order as Lead> Cadmium> Mercury, with values being 2.035, 2.493, 1.214, 1.671, 0.547 and 0.779 mg/kg fresh weight, respectively. No significant differences were observed among the levels of the toxic metals (Hg, Pb and Cd) in raw tuna and carp meat and their products. The results indicated that the total- soluble nitrogen (TSN) content of tuna was higher than of carp, and the ratios were 0.960 and 0.768 mg / 100 g, The content of non- protein nitrogen (NPN) was higher in tuna than in carp, where it recorded 0.242 and 0.229 mg /100 g, The percentage of soluble protein nitrogen (SPN) was higher in tuna than in carp, and the ratios were 0.718 and 0.539 mg /100 g, The results showed that the total volatile basic nitrogen content (TVBN) in tuna meat was also higher than that of carp. The values were 21.32 and 17.05 mg / 100g, while the TBA content of carp fats was higher than that of tuna fats, the proportions were. 0.405 and 0.345 mg / kg. The microbiological results revealed that the total bacterial count and numbers of Salmonella sp. and E. coli were decreased over time under freezing condition. Except for firmness and gumminess, no significant reduction in values of texture profiles was found in the tested products from zero to six months of frozen storage. However, for firmness and gumminess in all products, their values at zero and two months were very close which means no marked changes have existed. Finally, the organoleptic results concluded that tuna and carp products of burger, nuggets and fingers had a high acceptability for human consumption.