KINETICS OF QUALITY CHANGES OF GREEN PEAS AND WHITE BEANS DURING THERMAL-PROCESSING

The design of optimal thermal processes relies on relevant and accurate kinetic data for bacterial inactivation and quality evolution. By use of taste panels, kinetic data for quality evolution of peas (Pisum sativum L., var. Wavette) and white beans (Phaseolus vulgaris, subsp. nanus Metz., var. Manteca de leon) were obtained. The thermal destruction kinetics of these quality attributes was described using two alternative models, the thermal death time model (z- and D-value) and the Arrhenius model (E(a)-and k-value). Kinetic parameters were estimated by use of three least squares methods: two-step linear regression, multiple linear regression and nonlinear regression. Multilinear regression analysis was selected for parameter estimation. The following temperature coefficients were obtained: colour of peas (z = 26.4-degrees-C; E(a) = 102.4 kJ/mole), hardness of peas (z = 28.5-degrees-C, E(a) = 94.9 kJ/mole) hardness of beans (z = 21.3-degrees-C, E(a) = 130.8 kJ/mole) and appearance of beans (z = 24.3-degrees-C, E(a) = 118.7 kJ/mole).