Simulation of Potato Softening during Non-isothermal and Isothermal Processes

Abstract

Potato samples (7mm diam.×30mm length) were cooked in water with a cylindrical heating vessel in a temperature range from 85 to 105°C. Changes in hardness of the potato samples during cooking processes were measured for calculating the softening rate constant. Since the cooking processes consisted from the non-isothermal heating and cooling periods and the isothermal cooking period, the softening rate constants evaluated from the to toal time of the cooking processes meant merely the apparent rate constants for each cooking temperature. Thus the cooking time was corrected for evaluating the real softening rate parameters for the quoted temperature by estimating the progress of the softening of potato during the non-isothermal periods on the basis of a numerical integration method of softening rate. Relationships between the cooking curve of potato and the corrected cooking time showed good adaptation to a lst order rate equation. The activation energy was estimated to be 160kJ/mol, which was larger than 113kJ/mol being calculated from the apparent rate constants.