Effect of Pretreatment of Hydrostatic Pressure on Physicochemical Properties of Tilapia Muscle Protein Gels Induced by Setting

Tilapia meat pastes were subjected to pretreatments of hydrostatic pressure (50 to 300 MPa/4 degrees C/60 min) followed by setting (50 degrees C/60 min) with or without subsequent cooking (90 degrees C/20 min) to investigate the changes of rheological properties, gel-forming ability, whiteness, and protein solubility of gels. The gel by setting only as the control was elastic, rigid, and mainly constituted by covalent bonds. The gel by pretreatments of 50 MPa was similar to the control. A 100-MPa pretreatment induced a viscous and soft gel with mainly noncovalent bonds. The 200-MPa pretreatment produced a gel with strongest breaking force and strain compared with all the treatments in this study; moreover, the gel was mainly constituted by hydrogen bonds. A gel induced by a 300-MPa pretreatment was the most viscous. Via subsequent cooking (90 degrees C/20 min), all the gels became more rigid and elastic except that induced by a 100-MPa pretreatment.