Heat transfer analysis of tofu coagulation process

Tofu is produced by heating soy milk containing a coagulating agent. In thi s heating process, soy milk gradually coagulates during heating, and loses the fluidity. In order to examine a relationship between this coagulation a nd heat transfer mechanism, following experiments were carried Out. A tofu container was filled with soy milk and MgCl2, and then heated in a 90 degre esC constant temperature bath. Using the thermocouples installed in the con tainer, the temperature change during heating was measured. Perfectly solid ified tofu was cooled, and the heating experiment was carried out again. Th e temperature change of solidified tofu was equal to that in the coagulatio n process. By cutting off the container under heating, the coagulation proc ess of tofu was observed. The observation result showed that the solidifica tion 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, an d temperature distribution and temperature change of the container inside w ere estimated. It was proven that internal temperature change in the tofu c oagulation 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.