First order interaction of antioxidant capability of epicatechin was investigated in vitro by methods of response surface and central composite general rotary design.The results indicated that based on molar concentra...First order interaction of antioxidant capability of epicatechin was investigated in vitro by methods of response surface and central composite general rotary design.The results indicated that based on molar concentration,the ability to scavenge free radicals were in the order:ECG > EC > EGCG > ECG × EGCG > EGC.This suggests that the antioxidant ability of individual catechin had positively interacted effects under physiological condition.The free radical scavenging ability changed during tea processing.As compared with the fresh tea leaves,the leaves after indoor-spreading and Yao-Qing had a higher IC50of for DPPH free radical scavenge,being increased by 11.01%.It is deduced that the process technology of indoor-spreading might improve the quality of manufactured green tea.展开更多
文摘[目的/意义]茶多酚是衡量茶叶品质的关键指标,实现茶鲜叶茶多酚含量快速无损检测对于保障茶叶品质至关重要。同时,实现不同茶叶品种和叶位的快速识别,能够有效指导茶叶生产。[方法]本研究联用可见/短波近红外光谱(400~1050 nm)与长波近红外光谱(1051~1650 nm)技术研制一台茶鲜叶品质成分快速无损检测装置,采用多源数据融合(数据级和特征级融合)和机器学习算法,构建了不同茶叶品种、叶位和茶多酚含量快速检测模型。[结果与讨论]实验结果表明,不同茶树品种或不同叶位的茶多酚含量存在显著差异。相较于单一数据源,基于数据融合所建立的模型能有效提高预测性能,其中经过Savitzky-Golay卷积平滑预处理后结合特征级融合方法建立的偏最小二乘法判别分析模型(Partial Least Squares Discriminant Analysis,PLS-DA)对3个茶树品种和4个叶位识别的预测集准确率分别达到100%和87.93%。此外,基于数据级融合的一维卷积神经网络模型(One-Dimensional Convolutional Neural Network,1D-CNN)对茶鲜叶茶多酚含量的预测决定系数(Predicted Coefficient of Determination,R^(2)_(P))、预测均方根误差(Root Mean Square Error of Prediction,RMSEP)和残差预测偏差(Residual Predictive Deviation,RPD)分别为0.8020、0.6368%和2.2684,优于仅采用可见/短波近红外光谱和长波近红外光谱。[结论]该检测装置能够实现茶鲜叶茶多酚含量的快速检测,也能有效识别茶叶品种和叶位,为多源数据融合技术应用于指导茶叶生产加工提供新思路。
基金supported in part by Agriculture Science Technology Achievement Transformation Fund,P.R.China (No.459 in 2006.http://www.agrifund.cn/www/Agro/bulletin/200610/index.html)General Administration of Quality Supervision,inspection and Quarantine,P.R.China (201110210)Zhejiang Provincial Natural Science Foundation,P.R.China (No.Y3100683)
文摘First order interaction of antioxidant capability of epicatechin was investigated in vitro by methods of response surface and central composite general rotary design.The results indicated that based on molar concentration,the ability to scavenge free radicals were in the order:ECG > EC > EGCG > ECG × EGCG > EGC.This suggests that the antioxidant ability of individual catechin had positively interacted effects under physiological condition.The free radical scavenging ability changed during tea processing.As compared with the fresh tea leaves,the leaves after indoor-spreading and Yao-Qing had a higher IC50of for DPPH free radical scavenge,being increased by 11.01%.It is deduced that the process technology of indoor-spreading might improve the quality of manufactured green tea.
