Because the soy milk boiled in the iron pot has low concentrations as mentioned above, the net-like mesh structure in which protein molecules connect becomes rough (high concentrations make a fine-mesh net).
お釜で炊かれた豆乳は、前述の通り濃度が薄いので、蛋白分子が繋がった網の目構造の網の目が粗いものとなる（濃度が濃いと、緻密な網となる）。