Abstract
Rheological properties of rehydrated suspensions of freeze dried tomato ketchup were measured by Brabender Viscotron at the temperature range of $30-90^{\circ}C$, at the concentration of 15-50%, and at the shear rate of $0-250sec^{-1}$. At the shear rate of $0-210sec^{-1}$, tomato ketchup was found to be a thixotropic food product. The values of flow behavior index, consistency index and yield stress at the shear rate of $0-210sec^{-1}$, at the temperature of $30^{\circ}C$ and at the concentration of 33% , were 0.2131, 22.5047 $Pa\;sec^{-n}$, and 8.544 Pa, respectively. It was found that the apparent viscosity model for temperature was expressed by Andrade model and the model for concentration was expressed by Power model, and the model for both temperature and concentration was described by exponential and power models. The activation energies at the concentrations of 15, 20, 30, 33, 40, and 50% were 3.973, 4.985. 5.078, 5.226, 5.357, and 7.655 $kcal/g{\cdot}mole$, respectively.
토마토케찹의 리올로지 성질을 온도 $30-90^{\circ}C$, 농도 15-50% 전단속도 $0-250sec^{-1}$띤 범위에서 Brabender viscotron를 사용하여 측정한 결과는 다음과 같다. 토마토케찹은 전단속도 $0-210sec^{-1}$에서 의가소성을 나타내며, 항복응력을 가지는 Binghampseudoplastic으로 시간의존성을 나타내는 thixotropic 식품이었다. 전단속도 $0-210sec^{-1}$, 온도 $30^{\circ}C$, 농도 33%의 경우 유동지수, 점조도지수 및 항복응력은 각각 0.2131, 22.5047$(Pasec^{-n})$ 및 8.5443(Pa)이었다. 토마토케찹의 온도 및 농도에 따른 겉보기 점도 관계식은 각각 Andrade및 Power type식으로 나타낼 수 있었으며, 또한 온도와 농도에 따른 겉보기점도 관계식은 지수함수 모델로 표현할 수 있었다. 활성화 에너지는 농토 15,20,30,33,40 및 50%에서 3.973, 4.985, 5.078, 5.226, 5.357 및 7.655 kcal/g mole이었다.