Capillary Breakup Extensional Rheometer(CaBER)를 이용한 토마토 케첩의 신장 유변물성 측정

Power-law fluids exhibiting shear-thinning behavior frequently appear in food colloidal and emulsion systems. Because such fluids undergo both shear and extensional deformation, quantifying their extensional rheology is essential for understanding food flowability and sensory properties. In this study, the extensional rheological properties of tomato ketchup, a representative power-law fluid, were characterized using a Capillary Breakup Extensional Rheometer (CaBER). Experiments were performed under an acceleration a = 3 m/s2 and a final aspect ratio Λf = 1.83, varying the initial stretching velocity. A stable passive stretching regime, allowing rheological analysis, appeared at speeds above 60 mm/s. The dimensionless filament diameter evolution of ketchup followed a power-law model whose index matched that obtained from steady-shear viscosity. The extensional viscosity decreased with increasing extensional rate following a power-law trend, consistent with the shear viscosity-shear rate relationship.