51A-6

J. HOFFMAN and J. W. Park. OSU Seafood Lab and Dept of Food Science & Technology, Oregon State University, 2001 Marine Dr. #253, Astoria, OR 97103

JUSTIFICATION: The torsion test was developed and widely used as a fundamental method to measure fracture properties of surimi gels. However, accuracy relies an exact 1.0 cm. cross-sectional diameter at the center of the groove. Milling is also a timely process and may structurally damage soft gels. The use of molded gels instead of milled gels is likely to guarantee a consistent gel diameter, thereby eliminating human error in milling and measurement, as well as saving time.

OBJECTIVES: To evaluate the effect of cross-section diameter on shear stress and strain, to compare gelation properties between milled gels and molded gels, and to determine the effect of skin formation from molded gels, as well as the destructuring effect of milling on gels. The effect of individual variation in measuring diameter was also evaluated.

METHODS: Gels were made using stainless steel tubes and measured for shear stress and strain using the torsion method with various diameters. The surface of the gel, before and after milling, was measured microscopically. Gels were then made using the torsion mold tube and cooked for various lengths of time to see skin formation. Torsion testing was done for each time parameter, as well as evaluating its microscopic structure.

RESULTS: Shear stress values were extremely affected by the accuracy in diameter and increased as diameter increased. The effect of cross-section diameter on shear strain was not as large as shear stress, but there was a trend of strain reduction as diameter increased. An individual variation in measuring was found to be significant. Molded Gels provide consistency by eliminating human errors.

SIGNIFICANCE: Using dumbbell-shaped gels that are molded instead of milled will save time and maintain an accurate diameter control, which results in more precise gel evaluation. Without milling, individual variation in measuring the same gel and damage to the microstructure can also be eliminated.