基于色味指标光谱特性的贺兰山东麓干红葡萄酒产地细分

    Origin subdivision of dry red wine from Helan Mountain's East Foothill based on the spectral characteristics of the color and taste indicators

    • 摘要: 贺兰山东麓被认为是全球最适宜种植葡萄和生产优质葡萄酒的区域之一。贺兰山东麓葡萄酒产区自北向南已形成石嘴山、银川、永宁、青铜峡和红寺堡等5个产地的区划格局,但因产地风土各异,尚未建立科学规范的葡萄酒产地细分管理方法。为了协助宁夏贺兰山东麓产区强化干红葡萄酒产品区划管理,该研究以贺兰山东麓干红葡萄酒为研究对象,分析葡萄酒色味理化指标的相关性和产地差异性,并依据随机森林的节点权值确定了可反映产地信息的关键色味理化指标。然后,基于近红外光谱和化学计量学方法构建了各项指标的定量分析模型,并以光谱预测结果为输入量,训练了以ReLU为最佳激活函数的人工神经网络产地判别模型,实现了贺兰山东麓干红葡萄酒的产地细分。结果表明,酒石酸酯和pH值的产地差异性最为显著,多项色味理化指标之间存在较强的相关性,通过去低权值指标分析确定了酒石酸酯、多聚体花色苷、pH值、红/绿通道 a^* 、黄/蓝通道 b^* 、总单宁、单体花色苷、明度 L^* 、黄酮醇、滴定酸、离子化指数、乙醇指数、色度 C_ab^* 、总花色苷等14项关键色味理化指标。每项指标的光谱定量模型决定系数(r2)均高于0.90,相对分析误差(RPD)高于2.5,具有准确的定量分析能力;人工神经网络模型对石嘴山酒样判别的灵敏度(sensitivity,SEN)为100%,准确率(accuracy,CCR)为100%;对银川酒样判别的SEN为100%,CCR为90%;对永宁酒样判别的SEN为87.5%,CCR为93.33%;对青铜峡酒样判别的SEN为94.74%,CCR为100%;对红寺堡酒样判别的SEN为92.31%,CCR为92.31%,具有可靠的产地判别能力。该方法可为贺兰山东麓干红葡萄酒的产品区划管理提供技术支撑,有助于中国葡萄酒原产地保护制度的建立与发展。

       

      Abstract: Northwest Helan Mountain's East Foothill is considered as one of best regions for grapes growing and fermenting. Helan Mountain's East Foothill has been divided to 5 wine origin included Shizuishan, Yinchuan, Yongning, Qingtongxia and Hongsibu. These still not establishes a scientific approach to classify and manage the wine origin because of different terroir. This study analyzed correlation and origin’s variance wine color and taste indicators producing by Helan Mountain's East Foothill, and identified the color and taste indicators relating to wine origin based on the leaves node weights of random forest. Then, the Fourier transform near infrared spectra (FT-NIR) and chemometrics methods were used to construct quantitative analysis models for each indicator. Finally, using the database composed by the predictive values of the color and taste indicators as the input layer, an artificial neural networks (ANN) model with ReLU as the optimal activation function was trained to classify the specific origin of wine from Helan Mountain's East Foothill. The research results indicated that tartaric acid esters and pH values had significant difference between the wine from different origins, and many indicators had strong correlation with other indicator. Based on the analysis of removing low weights parameters one by one, 14 wine color and taste indicators (lightness L^* , redness a^* , yellowness b^* , chroma C_ab^* , total anthocyanins, monomer anthocyanin, polymeric anthocyanins, ionization index, flavonol, total tannin, ethanol index, tartaric acid ester, pH value, titrable acid) were considered as relevant to the origin. The FT-NIR quantitative analysis models of all 14 wine color and taste indicators had the bigger determination coefficient (r2c) than 0.95, the bigger relative percent deviation (RPDc) than 5, smaller root mean squared error (RMSEC) than 5% of the mean of each indicator for calibration set; and had the bigger determination coefficient (r2v) than 0.9, the bigger relative percent deviation (RPDv) than 2.5, smaller root mean squared error (RMSEV) than 15.7% of the mean of each indicator for validation set. The FT-NIR models had good quantitative prediction ability for 14 wine color and taste indicators. The 3 kinds of ANN models were established with different activation function include sigmoid, tanh and ReLU. The accuracies for determining of the origin of dry red wines were 84.06%, 91.30% and 94.20% separately. The model with ReLU as the activation function was proved to be the best one. Further analysis shows that the best model has 100% sensitivity and 100% accuracy in classifying the Shizishan wine samples, 100% sensitivity and 90% accuracy in classifying the Yanchuan wine samples, 87.5% sensitivity and 93.33% accuracy in classifying the Yongning wine samples, 94.74% sensitivity and 100% accuracy in classifying the Qingtongxia wine samples, 92.31% sensitivity and 92.31% accuracy in classifying the Hongsibu wine samples. The results indicated that the model proposed in this study can accurately discriminate the specific origin of wine from the Helan Mountain's East Foothill. This study would provide technical support for the product zoning management of dry red wines in the Helan Mountain's East Foothill, and help the establishment and development of Chinese wine origin protection system.

       

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