Effects of Liver Homogenate Addition on the Gel Properties of Surimi

In order to study the effects of animal liver addition on the gel properties of surimi, homogenized pig liver or duck liver was added to silver carp surimi at a level of 5% or 10%, respectively. The texture profile analysis, rheological properties, water distribution and intermolecular force of mixed surimi gel were determined. Results showed that with the addition of liver homogenates, the hardness, storage modulus (G') and loss modulus (G'') of surimi gel increased. And the whiteness, resilience and cohesiveness decreased, while water distribution was not greatly affected. When the content of liver homogenate increased from 5% to 10%, hardness did not change while whiteness, resilience and cohesiveness decreased further. The crude enzyme activity of transglutaminase (TGase) in duck liver homogenate was significantly higher than that of pig liver. At 5% addition level, protein resolubility of duck liver mixed surimi gel was higher than that of pig liver gel after breaking ionic, hydrogen, hydrophobic and disulfide bonds in the system. SDS-PAGE analysis showed that the myosin heavy chain in the duck liver group was less dense than that in the pig liver group, which might due to a greater involvement of myosin in TGase-mediated intermolecular cross-linking. Compared with the control group, the gel strength and the proportion of immobilized water in the pig liver group decreased significantly, while there was no difference in the duck liver group. The preliminary results showed that the addition of 5% pig liver homogenate had a significant effect on the gel properties of frozen silver carp surimi, which might be related to the endogenous TGase in the liver. However, this requires further investigation.