In order to design and to control various food transforming apparatuses such as for the chemical reactions, cooking, sterilization and so on of food materials, it is necessary to determine the Arrhenius' rate parameters from the non-isothermal experimental data of cooking and so on of food. In previous papers, we have studied the cooking rate equations of potato by various methods such as non-linear least square method (KUBOTA et al., 1981, 1988) and simple methods (OKAZAKI et al., 1991, 1992, ZHANG et al., 1993-B). In this paper, we investigated the determination of the rate parameters in non-isothermal processes by using simple methods proposed in previous papers. The modifyed cook value method in this paper was useful for finding the rate parameters in cooking rate equations. The corrected cooking time method (OKAZAKI et al., 1992) was useful too as simple method.