In order to design and to control automatically various cooking apparatuses44) such as a batch tank, a continuous belt containing tank, a continuous tube apparatuses and so on, it is necessary to measure the rheological properties, to determine the cooking-rate equation and to obtain the optimal operating time. In previous papers1-10), we have studied the rheological properties of liquid foods. In this paper, we studied a tubular type instrument for paste foods, an instrument that can be used for measuring the rheological properties and for determining the cooking-rate equation. We could define the rheological equation of wheat flour paste (dough). In previous papers16-18), we have studied the cooking-rate equation of noodles by the weighing method. Now, in this paper, we could determine the optimal operating time in the rheological method.