主成分分析技术对葡萄酒产地进行溯源

目的采用主成分分析技术对法国和山东产区的葡萄酒进行产地溯源。方法利用电感耦合等离子体质谱法(inductively coupled plasma mass spectroscopy,ICP-MS)、电感耦合等离子体发射光谱法(inductively coupled plasma emission spectrometry,ICP-OES)测定葡萄酒中30种无机元素及部分元素同位素含量,获取其中的元素成分信息,结合化学计量学中主成分分析技术(principal component analysis,PCA),分析不同地域样品的特征元素变量,研究筛选元素特征指纹。结果 PCA分析筛选出2个主成分因子,能对中国山东、法国波尔多产地的葡萄酒进行良好区分。利用PCA分析方法对中国山东、法国波尔多产区的葡萄酒样品的14种组分进行分析,筛选出~6Li、~7Li、~(10)B、~(11)B、Mg (280.270 nm)、P(213.618 nm)、Zn(213.857 nm)7种特征元素。结论该方法有望被应用于葡萄酒的产地溯源,可以为食品产地溯源技术的发展完善及相关部门的反欺诈监管提供技术积累。     

Adulteration detection of argan oil by inductively coupled plasma optical emission spectrometry

The singularity of the trace element profile of argan oil has been demonstrated by means of inductively coupled plasma optical emission measurement in combination with different chemometric approaches. The ability of multivariate analysis methods; such as hierarchical cluster analysis (HCA), principal component analysis (PCA), classification trees using Chi-squared Automatic Interaction Detector (CHAID) and discriminant analysis (DA) to achieve edible oils classification based on its type or variety from their elemental content have been investigated. The calculations were performed using 16 variables (contents of Na, Mg, Al, K, Ca, Ti, Fe, Co, Ni, Cu, Zn, Cd, Pr, Sm, Er and Bi at μg g⁻¹ level determined by ICP-OES). HCA is able to differentiate sunflower oil samples from the rest, however the discrimination of argan oil from olive, seeds and soya oils based on their different trace element composition is hard to achieve. The PCA analysis shows three different classes in the multidimensional space (PC1-3) representing sunflower, argan and a third group comprising olive, seeds and soya oils. CHAID method allows separating the entire vegetable oil dataset, providing a correct re-substitution rate of 94.12% for argan oil using only the concentration of K. DA performed using the same variables, provides also an acceptable average accuracy results of 93.65%, by the re-substitution method. DA has been successfully applied to the analysis adulterated argan oil by addition of cheaper vegetable oils.     

Multielement stable isotope ratio analysis of glycerol to determine its origin in wine

 The adulteration of wine with glycerol is considered to be a problem in European wine-producing countries. The latest control methods are mainly based on the detection of impurities from commercial products, but suffer from the raising efficiency of the purification processes. As there is little chance of being able to identify glycerol from different sources on the basis of a method which uses only one isotope, a multielement approach was tested. Glycerol from wine showed the lowest relative enrichment with D, mainly in position C-2, a relatively high ¹⁸O content, and very negative δ¹³C values, which significantly correlated with those of ethanol from the same wines. The isotopic data of glycerol samples from different sources were in agreement with those given by indices of origin (impurities). These data allowed us to identify the origin of these glycerol samples, i.e. whether they were produced industrially or synthesised by animals or plants. Glycerol of plant origin was most similar to glycerol found in wine. The combination of several isotopic data by discriminance analysis yielded clusters of data obtained from glycerol samples of similar origin. Taking into account the characteristics of possible mixtures, proof that wine has been adulterated depends on the origin and isotope levels of the added compound. This study showed that it is possible to prove that wine has been adulterated with glycerol from other sources when the latter is present at a concentration of 15% of the total glycerol content. Received: 27 October 1997 / Revised version: 12 February 1998     

Elemental Profile and <Superscript>87</Superscript>Sr/<Superscript>86</Superscript>Sr Isotope Ratio as Fingerprints for Geographical Traceability of Wines: an Approach on Romanian Wines

Wine geographical traceability is an important topic in the context of wine authentication and for that, many researchers worldwide have addressed this subject by developing different methodologies based on multivariate analysis of natural chemical composition data (inorganic or organic parameters) and isotopic signature. The goal of this work was to assess the potential of elemental composition and strontium isotope ratio (⁸⁷Sr/⁸⁶Sr) of wines from important wine-producing regions in Romania, located in relatively small geographical areas, in order to highlight reliable markers for wine geographical origin discrimination. Elemental profile determinations were performed by ICP-MS, GFAAS, and FAAS techniques after microwave acid digestion of the wine samples. The ⁸⁷Sr/⁸⁶Sr isotope ratio of the resulted extracts was determined by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS), after separating strontium and rubidium using cation-exchange chromatography with Dowex 50W-X8 resin and the complexation ability of the carboxylic acid EDTA. The variation of elemental composition (Ga, Sr, and Al), Ca/Sr ratio, and the ⁸⁷Sr/⁸⁶Sr ratio of the investigated wine clearly demonstrated that these variables are suitable tracers for wine geographic origin determination. The proposed methodology allowed a 100 % successful classification of wines according to the region of provenance.     

基于稀土元素指纹分析识别葡萄酒原产地

本研究为探讨稀土元素指纹分析对于葡萄酒原产地判别的可行性,采用电感耦合等离子体质谱法(inductively coupled plasma-mass spectrometry,ICP-MS)测定了三个原产地228个葡萄酒中的15种稀土元素含量,并对数据进行相关性分析、方差分析和判别分析。葡萄酒原产地和稀土元素含量间显著相关(p0.01),不同原产地间存在显著性差异(p0.001),沙城葡萄酒中稀土元素含量最低,通化最高,贺兰山东麓居中。Fisher线性判别分析(fisher linear discriminant analysis,FLD)模型对沙城、贺兰山东麓、通化三产地的交叉验证判别率分别为92.98%、98.25%、100.00%,外部验证判别率分别为84.21%、89.47%、100.00%;偏最小二乘判别分析(partial least squares-discriminant analysis,PLS-DA)模型判别能力略差,三个产地的交叉验证判别率分别为82.46%、98.25%、91.23%,外部验证判别率仅为73.68%、84.21%、100.00%。说明稀土元素含量结合多元统计分析可以应用于葡萄酒原产地的鉴别。     

Classification of Slovak white wines using artificial neural networks and discriminant techniques

This work demonstrates the possibility to use artificial neural networks (ANN) for the classification of white varietal wines. A multilayer perceptron technique using quick propagation and quasi-Newton propagation algorithms was the most successful. The developed methodology was applied to classify Slovak white wines of different variety, year of production and from different producers. The wine samples were analysed by the GC–MS technique taking into consideration mainly volatile species, which highly influence the wine aroma (terpenes, esters, alcohols). The analytical data were evaluated by means of the ANN and the classification results were compared with the analysis of variance (ANOVA). A good agreement amongst the applied computational methods has been observed and, in addition, further special information on the importance of the volatile compounds for the wine classification has been provided.     

Differentiation of Greek red wines on the basis of grape variety using attenuated total reflectance Fourier transform infrared spectroscopy

Mid-infrared spectroscopy combined with appropriate software was used in an attempt to differentiate Greek red wines of different varietals origin, including the cultivars Agiorgitiko (Nemea-Peloponnesus), Xinomavro (Naousa-Central Macedonia) and Merlot from Greece. Extract of wine phenolic components were investigated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The wine extracts were obtained by solid-phase extraction with C-18 columns and elution by methanol containing 0.01% hydrochloric acid. Libraries of spectra were created using sample from each wine variety. Spectra of unknown wine extracts were recorded and compared with those of the wine libraries and the rate of affinity (the match value) was measured automatically using the appropriate software (OMNIC ver. 7.3). The spectral region 1800–900 cm⁻¹ was used to ‘fingerprint’ wine on the basis of grape variety. This simple and fast method of analysis showed that wines from different grape varieties can be differentiated between them.     

Identification of the Origin of White Tea Based on Mineral Element Content

In recent years, the white tea industry has emerged. However, white tea market prices mainly based on the place of origin face certain challenges, such as shoddy and false advertising. To study origin identification technology, 64 white tea samples were collected from their main origins (Fuding City, Zhenghe County, and Jianyang City) and analyzed for 26 mineral elements (P, K, Fe, Ca, Mg, Al, Mn, and others) using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Results showed that white tea samples from different origins had different mineral contents, and samples collected from Zhenghe contained higher amounts of 10 mineral elements than samples from Fuding and Jianyang. By linear discriminant analysis (LDA), support vector machines (SVM) analysis, and K-Nearest Neighbor (KNN) methods, the majority of tea samples from different origins could be successfully differentiated according to their mineral elements. The accuracy of origin-based identification using mineral element analyses reached 98.44, 95.31, and 100 %, respectively. Therefore, mineral elements can be used to identify the origin of white tea samples, providing a reference for white tea identification.     

The application of SNIF‐NMR and IRMS combined with C,H and O isotopes for detecting the geographical origin of Chinese wines

The regional origin of Chinese wines was investigated using two important complementary techniques, site‐specific natural isotopic fractionation nuclear magnetic resonance (SNIF‐NMR) and isotope ratio mass spectrometry (IRMS). Twenty samples from five different grape varieties were collected from north Xinjiang in 2009, along with 100 wine samples from five different regions during 2010–2013. The (D/H)_I and (D/H)_II in wine ethanol ranged from 95.10 to 102.86 ppm and from 115.99 to 126.39 ppm using SNIF‐NMR, respectively. The ¹³C/¹²C of wine ethanol and ¹⁸O/¹⁶O of wine water were detected using IRMS. The δ¹³C value (?23.36‰) in coastal regions was higher than that in continental regions (?27.75‰). The temperature is the key for δ¹³C value. The δ¹⁸O ranged from ?1.94 to 4.57‰. The δ¹⁸O values were only positive in north Xinjiang which had the arid climate and strong sunshine. No difference was found for isotope ratios for wines made from five different grape varieties in north Xinjiang. All data evaluated by principal component analysis and linear discriminant analysis showed that the best method to distinguish the regional wine origin correctly is a combination of (D/H)_I, (D/H)_II, R, δ¹³C and δ¹⁸O. Therefore, natural multi‐elemental isotope ratios are effective in contributing to wine quality control in the Chinese market.     

δ18O of Ethanol in Wine and Spirits for Authentication Purposes

Since 1986 the European Union has established official isotopic analysis methods for detecting the illegal addition of sugar and water to wine and to enable geographical traceability. In this paper we investigate the possibility of using analysis of the ¹⁸O/¹⁶O stable isotope ratio (expressed as δ¹⁸O) of ethanol to improve detection of the watering of wine and to determine the origin of ethanol. Sixty‐nine authentic wine samples from all over Italy, 59 spirits from fruit and cereals, 5 chemically synthesized ethanols, one concentrated and rectified must, one beet and one cane sugar, one fresh must, and 6 waters with increasing δ¹⁸O values were considered. Ethanol was recovered by distillation, using a Cadiot spinning band column, following the official OIV methods. The residual water was trapped by storing the distillate for at least 24 h on a molecular sieve. The ¹⁸O/¹⁶O ratio was measured using a pyrolyser interfaced with an isotope ratio mass spectrometer. The δ^‐18O of ethanol is significantly related to the δ¹⁸O of the fermentation water and can be considered as a reliable internal reference. The values ranged from +24‰ to +36‰ in wine (years 2008 to 2012), +10‰ to +26‰ in fruit and cereal distillates, and from –2‰ to +12‰ in synthetic ethanol. The method was shown to be effective in improving detection of the watering of wine and determining the origin of ethanol (from grapes, other fruit, or synthesis), but not in detecting the addition of cane or beet sugar to wine.     

Progress in wine authentication: GC–C/P–IRMS measurements of glycerol and GC analysis of 2,3-butanediol stereoisomers

The determination of glycerol and 2,3-butanediol by photometric or enzymatic methods is well established. This paper reports on the direct assessment of glycerol and stereoselective analysis of 2,3-butanediol isomers in wine using capillary GC without any derivatisation. A “model wine” and commercially available wines, as well as wines of definite origin were investigated. The contents of glycerol and 2,3-butanediol and the ratio of (R,R)- and meso-2,3-butanediol were determined. Capillary GC has proved to be a reliable alternative in glycerol assessment from wine, thus a GC-IRMS method for authenticity assessment of glycerol was developed.δ¹³C_V‐PDB and δ¹⁸O_V‐SMOW multi-element IRMS-analysis of glycerol, an important by-product of wine fermentation, is reported. For that reason glycerol, extracted from a self-prepared “model wine”, from wines of definite origin, as well as commercially available wines, was investigated. Furthermore, the ¹⁸O/¹⁶O and ¹³C/¹²C isotope ratios of commercial glycerols from different origins were determined. In addition fermentation experiments with beet and cane sugar, and with grape juices were carried out. In order to check the influence of water on the oxygen isotope ratios, water from different places in Germany was used in the fermentation experiments with cane and beet sugar.     

Pedot modified electrodes in amperometric sensing for analysis of red wine samples

A poly(3,4-ethylendioxythiophene) modified electrode has been considered as a potentially useful amperometric sensor to use either alone or in the frame of a set of sensors bearing complementary information, i.e. within an electronic tongue. The sensor is proposed in blind analysis of red wines, for classification and calibration purposes. The data obtained from voltammetric measurements have been treated using partial least squares analysis. A calibration procedure has been performed to correlate results from analyses of wines, executed with traditional analytical methods, with the corresponding voltammetric responses. Moreover, classification models of the wine samples, based on quantitative parameters and qualitative information about origin and variety, have been built. The developed electrochemical sensor also allows the fast identification of samples exceeding threshold limits of meaningful parameters for quality control in the wine industry, such as SO₂, colour intensity and total polyphenols. The application of the system within a sensor array (electronic tongue) to fast pre-screening routine control procedure is proposed.     

新疆葡萄酒产区土壤、葡萄叶、葡萄果实和葡萄酒中矿物质元素含量及其相关性分析

该研究以三个新疆葡萄酒产区（伊犁、和硕、石河子）的土壤、葡萄叶片、果实、葡萄酒为试验试材,应用原子吸收分光光度计分析对其中14种矿物质元素进行检测,并通过显著性分析、相关性分析、偏最小二乘法判别分析（PLS-DA）剖析这些矿物质元素在不同产区土壤、叶片、果实、葡萄酒中的含量及分布特点。结果表明,在同一产区土壤、果实、葡萄酒矿物质元素含量分布相似且具有相关性,在不同产区之间同种矿物质元素具有显著差异（P<0.05）,三个产区土壤中Ca、Al、Fe含量最高,叶片、果实、葡萄酒中K、Mg、Ca含量最高。伊犁产区的土壤和果实矿物质元素间具有极显著相关性（P<0.01）,果实中Mn元素与土壤中Fe、Mn元素呈现极显著负相关（P<0.01）。PLS-DA结果表明,土壤中矿物质基本可区分产地差异,葡萄叶、果实、果酒中的矿物质可以对三产区信息进行区分。     

产地与品种对葡萄酒中酚类物质含量的影响

选取同一产地(天水)3 个葡萄品种：“西拉(Shiraz)”、“蛇龙珠 (Carbernet Gernischet)”、“赤霞珠(Cabernet Sauvignon)”所酿制的新鲜干红葡萄酒以及5 个不同产地(天水、和硕、玛纳斯、延庆和怀来)赤霞珠葡萄酒,采用高效液相色谱(HPLC)法分析葡萄酒中11 种酚酸、5 种黄烷-3- 醇、10 种黄酮醇和2 种黄酮的含量。结果表明：同一产地不同品种和同一品种不同产地间的葡萄酒中酚类物质的含量都存在显著差异。其中,赤霞珠葡萄酒是3 个葡萄品种中酚类物质含量最高的品种;在5 个不同产地中,延庆赤霞珠葡萄酒中酚酸含量最高,黄烷-3- 醇含量最高的为和硕赤霞珠葡萄酒,而怀来赤霞珠葡萄酒中所含黄酮醇含量最高。     

Simplified multi-element analysis of ground and instant coffees by ICP-OES and FAAS

A simplified alternative to the wet digestion sample preparation procedure for roasted ground and instant coffees has been developed and validated for the determination of different elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (Al, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, Zn) and flame atomic absorption spectrometry (FAAS) (Ca, Fe, K, Mg, Na). The proposed procedure, i.e. the ultrasound-assisted solubilisation in aqua regia, is quite fast and simple, requires minimal use of reagents, and demonstrated good analytical performance, i.e. accuracy from ?4.7% to 1.9%, precision within 0.5–8.6% and recovery in the range 93.5–103%. Detection limits of elements were from 0.086 ng ml^?1 (Sr) to 40 ng ml^?1 (Fe). A preliminary classification of 18 samples of ground and instant coffees was successfully made based on concentrations of selected elements and using principal component analysis and hierarchic cluster analysis.     

基于仿生嗅觉特征的黄酒产地判别研究

采用GC-Flash型电子鼻结合化学计量学方法对不同产地的黄酒进行区分判别。以主成分分析和判别因子分析法建立了产地判别模型。分析结果表明,在主成分分析判别模型中,绍兴原产地（地理标志）、非原产地（非地理标志）与绍兴以外地区的黄酒样品分别占据着不同位置;绍兴原产地和非原产地各自有较大的相对集中分布区间,存在一定的边缘交集,但是他们与绍兴以外地区的黄酒样品分界明显。判别因子法所建产地判别模型中,绍兴原产地、绍兴非原产地和绍兴以外地区的黄酒样品得到正确判别。研究表明,电子鼻结合化学计量学方法可较好地用于黄酒产地的判别。     

Discrimination Between Shaoxing Wines and Other Chinese Rice Wines by Near-Infrared Spectroscopy and Chemometrics

Shaoxing rice wine (also called Shaoxing wine) is the most well-known Chinese rice wine in China. The common fraudulent practice in the commercialization of Chinese rice wine is to sell wines from different geographical origins under the denomination of Shaoxing rice wine. In this study, the use of near-infrared (NIR) spectroscopy combined with chemometrics as a rapid tool for the discrimination of Chinese rice wine from three geographical origins (“Fujian”, “non-Shaoxing”, “Shaoxing”) has been preliminarily investigated. NIR spectra were collected in transmission mode in the wavelength range of 800–2,500 nm. Discriminant models were developed by principal component analysis (PCA), discriminant analysis (DA), and discriminant partial least-squares analysis (DPLS). The chemical properties of Chinese rice wine were also investigated to find out the difference between samples from three varied origins. The results showed that good classification could be obtained after spectral pre-treatment. The percentage of samples correctly classified by both DA and DPLS methods in calibration and validation set was 97.2% and 100%, respectively. The results demonstrated that NIR could be used as a simple and rapid technique to distinguish Shaoxing wines from non-Shaoxing wines and Fujian wines. To further validate the ability of NIR spectroscopy, more samples should be incorporated to build a more robust model.     

Multivariate authentication of the geographical origin of wines: a kernel SVM approach

During the WineDB European project, wine samples from four countries and three different vintages have been collected and their chemical content for 63 parameters was analyzed. The possibility to determine the country of origin of wines based on their chemical content was investigated during the project and the results from two multivariate classification techniques, namely partial least squares-discriminant analysis and kernel support vector machines, are described and compared. Attention has been paid to the development of efficient models in terms of cost of analysis and the problem of variable selection is considered. In particular, the kernel SVM approach leads to models which can reduce the annual updating effort of the classification models since a unique set of parameters can be used to discriminate authentic wines from different countries and different years of production, which is not the case when only PLS-DA is applied.     

Origin and Regionality of Wines—the Role of Molecular Spectroscopy

The origin of wine has an important relevance not only in relation to the sustainability of the production systems but also in relation to wine quality, having great impact in terms of the economy of small producer. Terms such as protected geographical status (PGS), protected designation of origin (PDO), protected geographical indication (PGI) and traditional speciality guaranteed (TSG) are been used to characterise wines from different regions and countries. Despite the number of papers and reports published in the literature in relation to issues such as authenticity and discrimination in wine, few reports can be found that explore the use of molecular spectroscopy to specifically target denomination of origin. This report reviews the use of molecular spectroscopy to address such issues within the wine industry.