In order to design and to control various cooking apparatuses, it is necessary to measure the cooking rate and to determine the cooking-rate equations. In a previous paper 1), we studied the cooking-rate equations of rice, udon and kishimen which are low water content foods using the weighing method for measuring the cooking rates.
In the present paper, we studied the measuring methods of the cooking rate and the cooking-rate equations of potato and sweet potato slices which are high water content foods. The results of this investigations are as follows.
(1) The impact-penetration method which is simple and useful for measurement the cooking-rate equations of high water content foods was used.
(2) The following cooking-rate equation postulated as simple rate equation with a S-shape constant α(－) was adopted with satisfaction for the cooking of potato and sweet potato slices:
dx/dθ= kn, α( 1－x)n(x+α)
where, x(－) is the cooking-ratio, θ(min) is the cooking time, and n(－), α(－) and kn, α(min) are the constants. The values ofαin the equation fixed n=1.0 showed about 0.1 for the used samples.