A COMPARATIVE STUDY ON PHYSICAL PROPERTIES AND CHEMICAL INTERACTIONS OF GELS FROM TILAPIA MEAT PASTES INDUCED BY HEAT AND PRESSURE

ABSTRACT The changes of physical properties and chemical interactions of gels from tilapia meat pastes applied to hydrostatic pressure (50–300 MPa; 4C; 30 min) or heat (30–70C; 30 min) treatments were investigated. The control gel (cooking at 90C for 20 min) was elastic and white. The meat paste treated by heat treatment began to form a gel texture at 50C, and the gel was elastic, rigid, white and mainly constituted by covalent bonds. Gels induced by pressure (above 200 MPa) were softer, more viscous than those by heat, meanwhile, they were mainly constituted by hydrogen bonds and hydrophobic interactions. Subsequent cooking process (90C; 20 min) would increase the hardness, elasticity and whiteness of the gels both induced by heat and pressure treatments. The appearance of the pressure‐induced gels showed glossiness and close to native color of meat pastes whereas that of the heat‐induced gels showed white but no luster. PRACTICAL APPLICATIONS The textural, chemical and physical characteristics of protein gels induced by heat and pressure are quite different; therefore combinations of heat and pressure treatments may produce various products. Pressure‐induced gels are mainly constituted by noncovalent bonds and are soft, viscous and glossy in appearance, whereas heat‐induced gels are mainly constituted by covalent bonds and are elastic, rigid and white. Different effects of combinations of heat and pressure treatments on protein gelation are applicable to food industries to manufacture various surimi products.