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  The purpose of this study was production of fish protein isolate and surimi from silver carp (Cyprinus carpio) and investigation of color characteristics as well as some chemical changes of their gel and powder. In this research, proteins were isolated using pH shifts method. Acidic pH (2.5 and 3.5) and basic pH (11 and 12) were used to produce fish protein isolate. Three steps of washing cycles were used for surimi production, which in the third step 0.2 % NaCl was used for more dehydration. Results showed that the product efficiency for fish protein isolate was significantly (P<0.05) more than that for surimi. Furthermore, the produced fish protein isolate using acidic pH had the most production efficiency amongst the samples. As a result, fish protein isolate had more recovery protein content compared to surimi. Determination of fat content of the samples showed that surimi contained significantly (P<0.05) lower reduction in fat compared to fish protein isolate. Investigation and comparison of color characteristics (L, a, b) attributed to gel and powder forms of the samples demonstrated that the produced fish protein isolate using pH 2.5 had the most intensity of lightness (L parameter) amongst the other samples. This study clearly showed that the production efficiency of fish protein isolate was higher than surimi.  In addition due to soluble proteins elimination in the process of surimi production, fish protein isolate had more protein content. The more reduction in fat content of fish protein isolate can be considered as an advantage because of possible increase in durability and safety of the products.  

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  This study aimed to investigate the quality characteristics of fish protein powder (FPP) from common carp raw surimi and its mince prepared by application of freeze-drying technique. To prepare test samples, either distilled water or 0.5M NaCl solution was used and parameters such as water holding capacity (WHC), emulsion capacity (EC), emulsion stability (ES) and oil absorption (OA) were determined. According to the results, WHC did not show any significant differences in samples prepared either by distilled water or 0.5M NaCl solution. In terms of EC, after 6, 12, 24, 48 and 72 h in samples prepared by use of 0.5M NaCl, no significant differences was observed between treatments. However, by use of distilled water, the differences became significantly (P<0.05) different. In this study, FFP from raw surimi showed higher and significant OA capacity compared to the one from fish mince. Finally, among color indices, L* and a* values showed significant difference between FFP from raw surimi and fish mince. It can be concluded that as there was no significant differences between FPP from common carp raw surimi and unwashed mince in terms of functional properties, therefore, if we expect lighter and whiter color in enriched product with protein powder, surimi FPP would be an appropriate choice, however, it needs to be confirmed by sensory evaluation test.  

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Fish protein, with its higher levels of essential amino acids than land animal protein, high digestibility, and strong binding ability with other proteins as a binder, emulsifier, or dispersing agent, has prompted food industry experts to conduct extensive research into various methods for producing concentrates and powders from it. In this research, protein powder was produced from silver carp meat (Hypophthalmichthys molitrix) by washing, heat and pH-shift methods, and then the amino acid composition of the protein powder produced by different methods was compared. The results of the comparison of the average of the amino acid composition indicated that heating treatment has the maximum amount of 306.08, 409.09 mg/g of protein and 75.0% of total essential and non-essential amino acids and EAA/NEAA ratio, respectively (p<0.05). and the minimum values ​​in the EAA and NEAA indices in the pH-shift treatment with the average values ​​of 229.39 and 321.08 mg/g of protein, respectively (p<0.05) Also, the minimum ratio of EAA/NEAA was assigned to the washing treatment with an average value of 0.68% (p<0.05). On the other hand, according to the general results and in line with determining and classifying the optimal treatment, it can be reported that heat treatment among other treatments, Due to the maximum amounts of total essential and non-essential amino acids and the EAA/NEAA ratio and the amount of Glu and Asp amino acids (two important umami amino acids),

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The aim of this study primary was to evaluate the production possibility of high quality protein powder type A (an almost odorless and tasteless powder with a maximum fat content of 0.75%) from milled meat of common carp through isopropanol solvent extraction method, and then the replacement of produced fish protein powder  (FPP) together with the transglutaminase enzyme instead of flour in the formulation of cake and evaluation of the sensory quality, physicochemical properties and nutritional value at ambient temperature. For experiments, 1 control and 6 experimental cakes treated with 6 and 8% concentrations of fish protein powder by adding 0.5 and 1% transglutaminase levels were considered. The control treatment was free of fish protein and enzyme powders. Factors such as fat, protein, ash and moisture content were significantly different in enriched and control treatments (P<0.05). Peroxide value and pH increased significantly in experimental treatments containing 8% FPP in comparison with other treatments and acidity decreased significantly (P<0.05). Sensory factors including taste, color, texture, odor, and overall acceptability of treatments contain 6% FPP and  0.5% transglutaminase enzyme had no significant difference compared to the control sample (P>0.05). Wih adding transglutaminase enzyme to cakes containing fish protein powder improved the physicochemical properties of the samples.With considering the results and the absence of a significant difference between samples contain 6% FPP and 0.5% enzyme transglutaminase compared to control, this treatment can be recommended as a suitable combination for fish cake.