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Aims: The functional properties of proteins extracted by Isoelectric Solubilization/Precipitation (ISP) method are influenced by various factors such as the use of acid or base while protein extraction. The aim of this study was to investigate the functional properties of protein extracted from Crucian carp (Carassius carassius), using acidic and basic ISP method.
Materials & Methods: This experimental study was carried out on 56 Crucian carps in Bandar Torkaman City, Iran. The minced meat of fish was randomly divided to 2 homogeneous groups for implementing acidic and basic ISP method. The protein was isolated from meat and its functional properties were evaluated. The data were analyzed by SPSS 21 software, using two-sample t-test.
Findings: The protein extracted from Crucian carp meat had a significant difference in acidic and basic treatments (p<0.05). There was no difference in water holding between two treatments (p>0.05). The emulsion capacity of the extracted protein was significantly higher in basic treatment than the acidic treatment (p<0.05). The emulsion stability index was also significantly higher in basic treatment than acidic treatment. All samples had a flow behavior index (n) less than 1, indicating that these samples had a pseudoplastic behavior.
Conclusion: The protein extracted from Crucian carp meat is higher in the acidic treatment, but the basic treatment has better functional properties. The basic treatment has a higher emulsion capacity than the acidic treatment, and the stability index is high in the basic treatment. Protein solutions as well as acidic and basic emulsions have a pseudoplastic property. The amount of food viscosity is higher in acidic treatments compared to the basic treatment.

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Crucian carp (Carassiu sauratus) is one of the economic species of Anzali wetland. In recent years, the demand of high consumption was found, because of its low price and high level of catch. This study focused on accumulation of heavy metals(Cd, Pb and Zn) in the edible tissues of Crucian.Sampling were done in 3  stations (West,Center and East) of Anzali  wetland in 1391. In this study 10samples were collected from each site in the standard weight by grill net, randomly. After separation of tissues, preparing of samples were conducted by using of wet digestion method and  mixed acid ( HNO3/HCLO4).After filtration, the prepared samples were determined for Cd, Pb and Zn by  using a flam atomic absorption spectophotmeter (AA),SHIMADZU model 680.The levels of metals were compared with the standard of American Food and Drug Administration (FDA)  and the world Health Organization (WHO). The average concentrations of cadmium in the soft tissue of crucian were 0.07 , 0.05 and 0.05 μ g / g dry base for West, East and Center of Wetland. For Zinc, average concentrations for West,Center and East were 58.45, 46.4 and 49.7 μ g / g dw, respectively. The result showed that,there were not significant differences (P>0.05) between stations about the Cadmium, Lead and Zinc in the tissues of Crucian. Concentrations of Pb and Zn were higher than of standars levels of WHO and FDA.