基于计算机视觉的绿茶炒干中在制品理化变化研究

为探明绿茶炒干过程中在制品理化变化规律,利用计算机视觉技术对其外形和色泽的变化进行实时监测,同时测定其主要成分变化。结果显示,随着炒干时间的增加:(1)在制品曲率半径值逐渐下降,10~30 min下降最快;R、G、B和平均灰度值呈先下降后上升的趋势,一致性则呈相反趋势;色相H值显著上升,饱和度S值显著下降。(2)表没食子儿茶素没食子酸酯(EGCG)、表没食子儿茶素(EGC)、叶绿素a、叶绿素b和类胡萝卜素含量显著下降,没食子儿茶素没食子酸酯(GCG)含量显著上升。试验结果表明,曲率半径值与含水率、叶温呈极显著相关,H值与叶绿素a、叶绿素b含量等呈极显著相关,S值与叶绿素a、类胡萝卜素和表儿茶素没食子酸酯(ECG)含量呈极显著相关。EGCG和H值线性拟合度最高,为0.922 1。今后可通过在线监测含水率、叶温和H值等来预测绿茶炒干过程中曲率半径值和化学成分的变化。

Study on the Changes of Physical and Chemical Components during the Frying Process of Green Tea by Computer Vision

In order to find out the physical and chemical changes during the frying process of green tea, the computer vision technology was applied to real-time monitor the changes of color and shape, and chemical changes were simultaneously measured. The results show that with the increase of frying time, (1) the radius of curvature of unfinished tea gradually decreased, which showed the highest decreasing rate from 10-30 min. R, G, B and average gray value decreased first and then rose. The consistency value was opposite to their trends, with the extreme value in 20 min. H value increased significantly, S value decreased significantly. (2) Epigallocatechin gallate (EGCG), epigallocatechin (EGC), chlorophyll a, chlorophyll b and carotenoids decreased significantly, while gallocatechin gallate (GCG) increased significantly. Experimental results show that the radius of curvature was highly correlated with water content and leaf temperature. H was significantly correlated with chlorophyll a, chlorophyll b. S was significantly correlated with chlorophyll a, carotenoids and epicatechin gallate (ECG). The linear fit of EGCG and H values showed the highest value at 0.922 1. In the future, water content, leaf temperature and H value could be monitored online to predict changes of the radius of curvature and chemical composition during frying.