Color Prediction and Quality Analysis of Ginkgo biloba Seeds under Medium and Short Wave Infrared Drying

In order to predict the color change of GB seeds and improve quality of dried production during the drying process, the medium and short wave infrared drying technology was applied to the GB seeds drying process. The drying characteristics and color change kinetics of GB seeds at different drying temperatures (60, 70, 80 and 90℃) were studied. The color prediction model of GB seeds was established by using artificial neural network (ANN). The quality parameters such as rehydration rate, total flavone content, oxidation activity and microstructure of GB seeds were also studied. The results demonstrated that the whole drying process occurred in the falling rate period. The drying time decreased significantly with the drying temperature increased from 60 to 80℃. When the drying temperature increased from 80 to 90℃, there was no significant difference in drying time of GB samples. The color change kinetics of GB seeds illustrated that L^* value decreased gradually, a^* value and b^* value increased at first and then decreased, and the total color difference ΔE showed a two-stage increase during the drying process. Results showed that ANN model could well predict the color change during the drying process. According to the quality parameters of dried GB seeds samples, the optimum rehydration ratio of 1.580, the best antioxidant activity of 175.70 μmol trolox/100 g and the better total flavone content of 198.40 mg/100 g were obtained at drying temperature of 70℃. The microstructure of GB seeds was observed by scanning electron microscope (SEM). The results showed that starch granules still maintained a complete round or oval structure at drying temperature lower than 70℃. When the drying temperature was higher than 80℃, it was found that the structure of starch granules was obviously destroyed.