39D-9

J. A. RAMíREZ, Depto de Ciencia y Tecnología de Alimentos, Universidad Autónoma de Tamaulipas, Apdo Postal 1015, Reynosa, Tamaulipas, 88740, Mexico, I. A. Santos-Sánchez, Depto. de Ciencia y tecnología de Alimentos, Universidad Autónoma de Tamaulipas, M. T. MORRISSEY, Seafood Laboratory/Dept of Food Science and Technology, Oregon State University, Room 253, 2001 Marine Dr. Astoria, Astoria, OR 97103, and M. VáZQUEZ, Depto. Química Analítica, Bromatología y Nutrición, Universidad de Santiago de Compostela, Área de Tecnología de los Alimentos, Escuela Politécnica Superior, Lugo, 27002, Spain.

JUSTIFICATION: Surimi gels from cold water species present better mechanical properties with low temperature setting, while gels from warm water species present better attributes with high temperature setting. The discovery of endogenous TGase a calcium dependent enzyme, and its effect on textural characteristics of surimi gels has caused the search of optimal conditions for surimi gelation of several fish species.

OBJECTIVES: The objective of this work was to determine the optimal conditions to obtain the setting phenomenon in silver carp (Hypophtamichtys molitrix), a warm water fish.

METHODS: Surimi sols were obtained with 2.5% sodium chloride and incubated at 25, 35 or 45°C during 1, 3 or 5 h. All gels were heated at 90 °C by 15 min after incubations. Controls were performed by heating without incubation. Surimi gels were analyzed employing the torsion test to determine shear stress and shear strain at the failure. A second-order, incomplete, factorial design of experiments was used to develop empirical models providing a quantitative interpretation of the relationship between the operational conditions of the setting process.

RESULTS: The shear stress varied over a wide range (23.6 - 78.2 kPa). Shear stress was almost not affected by setting phenomenon, varying within the narrow range 0.94-1.45. Optimal conditions were dependent on both temperature and time. Maximum values of shear strain were obtained at 39, 35 and 33 °C for 1, 3 or 5 hours respectively. These results suggest that setting is a phenomenon dependent on protein denaturation/aggregation and enzymatic activity.

SIGNIFICANCE: The optimal setting temperature for silver carp was higher that those recomended for cold water fishes which suggest an enviromental role. The treatment of 40°C/ 30 min accepted as appropiated for obtention of setting phenomenon for most of the warm water fish might be not necesarily the optimal conditions.