基于傅里叶变换红外光谱快速检测新疆干红葡萄酒中的多糖类物质

    Rapid identification of polysaccharides in Xinjiang dry red wines based on Fourier Transform Infrared1 spectroscopy

    • 摘要: 为了开发干红葡萄酒中多糖类物质的快速无损检测方法,该研究通过衰减全反射-傅里叶变换红外光谱仪(attenuated total reflectance-fourier transform infrared, ATR-FTIR)结合化学计量学方法,建立了一种高效、精准的检测技术。试验以新疆产区100款干红葡萄酒为试材,通过高效液相色谱(high performance liquid chromatography-photodiode array detection, HPLC-PDA)定量分析单糖,酒样中不同类别多糖含量依据各自特征结构的单糖浓度按照一定的摩尔比例进行计算,包括总可溶性多糖(total soluble polysaccharides, TSP)、甘露糖蛋白(mannoprotein, MP)、富含阿拉伯糖-半乳糖的多糖(arabinogalactan-rich polysaccharide, PRAG)、鼠李半乳糖醛酸聚糖II型(rhamnogalacturonan II, RG-II)、高半乳糖醛酸聚糖(homogalacturonan, HG)和葡聚糖(glucan, GL))。葡萄酒的中红外光谱信息通过ATR-FTIR采集,采用标准正态变换(standard normal variate, SNV)和多元散射校正(multiplicative scatter correction, MSC)等方法进行光谱预处理,随后利用竞争性自适应重加权算法(competitve adaptive reweighted sampling, CARS)进行波段筛选,最后结合偏最小二乘回归(partial least squares regression, PLSR)和反向传播神经网络(backpropagation neural network, BPNN)两种建模方法,建模和预测以及评价指标用1900 900 cm−1波段的光谱特征信息拟合HPLC-PDA测得几种多糖类物质的含量。结果表明,供试酒样之间不同类别多糖含量差异较大,其中TSP含量为(859.41±293.65) mg/L,MP为(208.08±78.42) mg/L,PRAG 为(418.30±140.00) mg/L,RG-II为(113.17±55.11 )mg/L,GL为(95.46±62.10 )mg/L,HG为(24.41±55.86) mg/L。采用1900~900 cm−1筛选出的特征信息拟合供试酒样中的几种多糖含量,利用线性与非线性校正方法建模,结果表明,ATR-FTIR模型对葡萄酒中几类多糖的含量均具备良好的预测能力。其中,PLSR模型的预测性能优于BPNN,多糖(TSP、MP、PRAG、RG-Ⅱ和GL)的特征波段和含量之间的PLSR模型训练集决定系数(Rc2)分别为0.98、0.96、0.92、0.99、0.98,预测集决定系数(Rp2)分别为0.85、0.92、0.83、0.83、0.84,训练集相对分析误差(RPDc)分别为6.50、5.31、3.62、9.10、7.86,预测集相对分析误差(RPDP)分别为2.68、3.99、2.44、2.52、2.37。该研究开发的ATR-FTIR检测干红葡萄酒多糖类物质的方法,利用多糖特征波段1900 ~900 cm−1的光谱信息,可对TSP、MP、PRAG、RG-Ⅱ和GL几种多糖含量进行准确预测,具有快速无损检测干红葡萄酒中多糖类物质的应用潜力。

       

      Abstract: The purpose of this study was to develop a rapid non-destructive detection on of polysaccharides in the dry red wine by the attenuating total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) with chemometric technologies. 100 dry red wines were also collected from the Xinjiang production area of western China. Alcohol precipitation was utilized to extract the wine polysaccharides from these test materials. After that, the polysaccharide powder was obtained after vacuum freeze-drying. Then, the polysaccharides were decomposed into the monosaccharides with the trifluoroacetic acid. The monosaccharides were quantitatively characterized by high high-performance liquid chromatography (HPLC-PDA). As such, the different types of polysaccharides were identified from the wine samples. The monosaccharide concentration was calculated to compare their respective characteristic structures in the molar ratio, including total soluble polysaccharides (TSP), mannosan protein (MP), arabinose-galactose-rich polysaccharides (PRAG), rhamnogalacturonic acid glycan type II (RG-II), homogalacturonized glycan (HG), and dextran (GL). The mid-infrared spectra of wine was were also collected by ATR-FTIR. The spectral preprocessing was carried out by standard normal transform (SNV) and multivariate scattering correction (MSC). The competitive adaptive reweighting algorithm (CARS) was followed for band screening. Finally, the partial least squares regression (PLSR) and backpropagation neural network (BPNN) were combined to simulate, predict and evaluate the indicators. The spectral characteristic information in the 1900~900 cm-1 band was screened to determine the content of several polysaccharide substances that were measured by HPLC-PDA. The results indicate that the content of various polysaccharide varied greatly among the test liquor samples, with the TSP content of (859.41±293.65) mg/L, MP (208.08±78.42) mg/L, PRAG (418.30±140.00) mg/L, RG-II (113.17±55.11) mg/L, GL (95.46±62.10) mg/L, and HG (24.41±55.86) mg/L. The content of several polysaccharides in the test wine samples was also verified using the linear and nonlinear correction. The ATR-FTIR model shared the a better prediction on the content of several polysaccharides in wine. The PLSR model showed the better performance than the BPNN. The coefficient of determination (Rc2) values of the PLSR model between the characteristic bands and the content of polysaccharides (TSP, MP, PRAG, RG-II, and GL) were 0.98, 0.96, 0.92, 0.99, 0.98, respectively. The coefficient of determination (Rp2) values were 0.85, 0.92, 0.83, 0.83, 0.84, respectively. The relative analysis errors (RPDc) in the training set were 6.50, 5.31, 3.62, 9.10, and 7.86, respectively. The relative analysis errors (RPDP) of the prediction set were 2.68, 3.99, 2.44, 2.52, and 2.37, respectively. Therefore, the ATR-FTIR can be expected to detect the polysaccharides in dry red wine. The content of polysaccharides can be accurately predicted in the TSP, MP, PRAG, RG-II, and GL, according to the spectral characteristic band of 1900 ~900 cm-1. The finding can provide the application potential for the rapid and nondestructive detection of polysaccharides in dry red wine.

       

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