Color Change Kinetics of American Ginseng (Panax quinquefolium) Slices During Air Impingement Drying

Abstract

The color change kinetics of American ginseng (Panax quinquefolium) slices were investigated in an air impingement dryer under different drying temperatures (35, 45, 55, and 65°C) using the CIE Lab color parameters (L*, a*, b*) as the assessment indicators. Results illustrated that all three color parameters (L*, a*, b*) increased with drying time. The L* value decreased with increasing drying temperature. However, a* and b* values increased with the increase in drying temperature. Furthermore, at the initial drying stage the change rate of L* increased significantly, while towards the end of drying it reduced significantly. As regards a*, it slowly changed at the initial and final drying stages rather than in the intermediate drying stage. In the case of b*, it increased with increasing drying time and drying temperature during the whole process. The zero-order, first-order, and fractional conversion models were fitted to the experimental data, and the model's parameters were determined using linear regression analysis. By comparing the fitting of kinetic models to the experimental data, the most suitable model was selected to describe the color change kinetics. An Arrhenius equation was used to calculate the activation energy for color change kinetics and it was found that the values were 33.87–38.55, 56.48, and 74.03 kJ/mol for L*, a*, and b*, respectively. The findings of this work contribute to a better understanding of ginseng color changes kinetics during drying, and the established change kinetics models are a good tool for predicting, evaluating, and controlling of color change of American ginseng during its drying process.

Keywords:

• American ginseng slices
• Color change kinetics
• Air impingement drying
• Modeling
• Activation energy

ACKNOWLEDGEMENT

We thank Ms. Rachel Clarke of the School of Biosystems Engineering, University College Dublin, for enhancing the language.

Notes

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ldrt.