A study on the degradation kinetics of visual green colour in spinach (Spinacea oleracea L.) and the effect of salt therein

The effect of salt on the degradation of visual green colour '-a' in spinach puree (Spinacea oleracea L.) over a temperature range of 50-120 degreesC (steady state temperature process) as well as under conditions of normal open pan cooking, pressure-cooking and a newly developed and patented fuel-efficient EcoCooker has been studied (unsteady state heating process). The degradation of visual green colour as measured by '-a' value followed a first order kinetics, where the rate constant increased with an increase in the temperature. The temperature dependence of degradation was adequately modeled by Arrhenius equation. A mathematical model has been developed using the steady state kinetic parameters obtained to predict the losses of green colour from the time-temperature data of the unsteady state heating/processing method. The results obtained indicate a protective effect of salt on the degradation of visual green colour. (C) 2003 Elsevier Ltd. All rights reserved.