KINETICS OF THERMAL SOFTENING OF WHITE BEANS EVALUATED BY A SENSORY PANEL AND THE FMC TENDEROMETER

The temperature dependence of the rate index of thermal softening of w hite beans (Phaseolus vulgaris, subsp. nanus Metz. variety Manteca de Leon) was determined within the temperature range of 90C to 122C using an industrial FMC tenderometer and a trained sensory panel. Based on sensorial results a first order reaction was assumed, whereas the tend erometer values were described by a biphasic model. Using a multiple l inear regression analysis on the sensorial data, the activation energy for the heat induced firmness degradation of beans was calculated as 130.8 kJ/mole. Activation energies of both phases of the biphasic mode l were obtained by a two-step linear regression on the tenderometer da ta. Activation energies of both phases were equal, namely 105.1 kJ/mol e.