Heat transfer analysis of tofu coagulation process
2001
Sakai, N. (Tokyo Univ. of Fisheries (Japan)) | Hagiwara, T. | Yang, H. | Tojo, A.
Tofu is produced by heating soy milk containing a coagulating agent. In this heating process, soy milk gradually coagulates during heating, and loses the fluidity. In order to examine a relationship between this coagulation and heat transfer mechanism, following experiments were carried out. A tofu container was filled with soy milk and MgCl2, and then heated in a 90 deg C constant temperature bath. Using the thermocouples installed in the container, the temperature change during heating was measured. Perfectly solidified tofu was cooled, and the heating experiment was carried out again. The temperature change of solidified tofu was equal to that in the coagulation process. By cutting off the container under heating, the coagulation process of tofu was observed. The observation result showed that the solidification occurred in the initial stage. From the above results, it was deduced that conductive heat transfer was more dominant than the natural convection. A heat conduction equation was solved using the finite element method, and temperature distribution and temperature change of the container inside were estimated. It was proven that internal temperature change in the tofu coagulation process was predictable by solving the heat conduction equation, because numerically calculated temperature agreed with the measured value well. In addition, it was shown that the two-dimensional analytic solution agreed with the solution by the finite element method and that temperature prediction is possible using the analytic solution.
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