36D-18 |
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J. W. PARK, Dept. of Food Science & Technology, Oregon State Univ., OSU Seafood Research Lab., 2001 Marine Dr., Rm. 253, Astoria, OR 97103 and B.-Y. Kim, Dept. of Food Science & Technology, Kyung Hee Univ., Seochun 1, Yongin, South Korea. Viscosity often determines the flow of products and controls the productivity. However, due to the nature of fish muscle proteins (surimi) that easily entangle upon setting or heating, the viscosity is not properly measured using an ordinary Brookfield viscometer. In addition, the dilution factor of surimi paste without salt does not show a linear relationship with a viscosity value. As a result the quality control to oversee the production flow is not easily maintained. Consequently, there is a significant need for a quick and easy method to determine viscosity of fish muscle proteins. Objectives were to develop a capillary extrusion viscometer and equations for measuring the viscosity of fish protein paste. We further wanted to estimate the quality of gel texture using the viscosity values. A capillary extrusion viscometer with a plunger (tube length: 3 and 1 cm, tube diameter: 6 mm) was developed. This viscometer was attached to a TA Plus texture analyzer (Stable Micro System). The viscosity of surimi paste was measured as a function of moisture content(75-80%), salt content (2-4%), and egg white content (2-4%). Each value was also compared with fundamental dynamic values measured using Bohlin CS50 dynamic shear rheometer. As moisture, salt, and egg white contents increased, viscosity gradually decreased. These viscosity values, obtained using our new capillary extrusion viscometer, were well correlated to those values measured using dynamic shear rheometer. The viscosity values showed a reversible relationship with gel failure properties of surimi gel, especially shear stress from the torsion test. This easy viscosity measurement can effectively facilitate production control of comminuted muscle food, including surimi paste. Based on simple linear equations, the viscosity values could be used to quickly and easily to predict final gel quality.
Session 36D, Food Engineering: Rheology
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |