Application of the weibull model to describe the kinetic behaviors of thiol decolorizers in chlorogenic acid-lysine solutions

Abstract

Thiols (cysteine and glutathione) were explored as potential decolorization agents to mitigate green pigment formation in chlorogenic acid quinone-lysine solutions. Reparameterizations of the Weibull cumulative distribution function were applied to describe the time-dependence of greening under varying pH conditions. Repeated fitting of 3-parameter models (RMSE = 0.0111, CVRMSE = 1.55%) indicated the linear dependence of model parameters on thiol concentration. A 6-parameter Weibull model incorporating time and initial thiol concentration (RMSE = 0.0255, CVRMSE = 3.56%) accurately predicted green color development. Calculated model parameters descriptive of greening rate, terminal greening magnitude, and lag time before greening onset facilitated comparison of the relative effectiveness of each thiol based on concentration. Bayesian regression of the model yielded nearly similar predictive power (RMSE = 0.0272, CVRMSE = 3.80%). Glutathione yielded longer lag time durations at both pH 8.0 and 9.0 but yielded less green solutions only at pH 9.0.