Characterisation of volatile components of Pinotage wines using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC–TOFMS)

As part of the ongoing research into the chemical composition of the uniquely South African wine cultivar Pinotage, the volatile composition of nine young wines of this cultivar was investigated using comprehensive two-dimensional gas chromatography (GC × GC) in combination with time-of-flight mass spectrometry (TOFMS). Headspace solid phase micro-extraction (HS-SPME) using a carboxen/polydimethylsiloxane (CAR/PDMS) fibre was used to extract the volatile compounds from the wine matrix. Extracts were analysed using an in-house developed GC × GC system equipped with a single jet, liquid nitrogen-based cryogenic modulator. In the current study, 206 compounds previously reported in wine and related matrices have been detected in nine Pinotage wines. Positive identification for 48 compounds was performed using authentic standards, while tentative identification of 158 compounds was based on deconvoluted mass spectra and comparison of linear retention indices (LRI) with literature values. Identified compounds included esters, alcohols, aldehydes, ketones, acids, acetals, furans and lactones, sulphur compounds, nitrogen compounds, terpenes, hydrocarbons, volatile phenols and pyrans. Volatile compounds potentially capable of influencing wine aroma are highlighted. Many of the compounds were common to all 9 wines, although volatile components unique to specific samples were also observed. The results represent the most detailed characterisation of volatile constituents of this cultivar reported to date.     

Comprehensive two-dimensional gas chromatography–mass spectrometry analysis and comparison of volatile organic compounds in Brazilian cachaça and selected spirits

This paper presents the application of comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC×GC/TOFMS) using the longitudinal modulated cryogenic system (LMCS) device, to the aroma analysis of spirit samples. The volatile organic compounds present in samples of a Brazilian cane sugar spirit were collected by using a solid-phase microextraction (SPME) method. Other samples studied included gin, vodka, whiskey, tequila and flavoured liqueurs. In this study GC×GC/TOFMS with a bi-dimensional non-polar – polar phase column set comprising of a first dimension BPX5 primary column and a second dimension BP20 second column enabled the tentative identification of 95 compounds in cachaça. In excess of 200 compounds were found amongst group of samples that were analysed. The results, presented as peak apex plots, showed that groups of compounds were present in well-defined regions of the 2D separation space in each beverage, making it possible to recognise the differences and similarities among the spirit samples.     

Tracing the geographical origin of honeys based on volatile compounds profiles assessment using pattern recognition techniques

The goal of this study was to examine the possibility of verifying the geographical origin of honeys based on the profiles of volatile compounds. A head-space solid phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS) was used to analyze the volatiles in honeys with various geographical and floral origins. Once the analytical data were collected, supervised pattern recognition techniques were applied to construct classification/discrimination rules to predict the origin of samples on the basis of their profiles of volatile compounds. Specifically, linear discriminant analysis (LDA), soft independent modeling of class analogies (SIMCA), discriminant partial least squares (DPLS) and support vector machines (SVM) with the recently proposed Pearson VII universal kernel (PUK) were used in our study to discriminate between Corsican and non-Corsican honeys. Although DPLS and LDA provided models with high sensitivities and specificities, the best performance was achieved by the SVM using PUK. The results of this study demonstrated that GC × GC–TOFMS combined with methods like LDA, DPLS and SVM can be successfully applied to detect mislabeling of Corsican honeys.     

Aroma profiles of five basil (Ocimum basilicum L.) cultivars grown under conventional and organic conditions

A headspace solid-phase microextraction (HS-SPME) method coupled to gas chromatography–ion trap mass spectrometry (GC–ITMS) has been developed and applied for profiling of volatile compounds released from five Ocimum basilicum L. cultivars grown under both organic and conventional conditions. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOFMS) was employed for confirmation of identity of volatiles extracted from the basil headspace by SPME.     

The influence of yeast on the aroma of Sauvignon Blanc wine

The main objective of this study was to investigate the effect of different Saccharomyces cerevisiae wine yeast strains on the concentration of aroma-enhancing volatile thiols and fermentation metabolites in Sauvignon Blanc wine. Seven commercial wine yeast strains were selected based on their putative ability to modulate the concentrations of the fruity volatile thiols, 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercapto-hexanol (3MH) and 3-mercapto-hexylacetate (3MHA). Each of these yeasts was used to produce Sauvignon Blanc wines under controlled conditions, in triplicate, in 20-L quantities. The levels of 4MMP, 3MH and 3MHA in these wines were quantified using the p-hydroxymercuribenzoate method. In addition, a total of 24 volatile yeast-derived fermentation aroma compounds were also quantified using headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME–GC–MS). Formal sensory analysis was conducted by 12 trained assessors and, additionally, a panel of 24 experienced wine industry professionals assessed the wines and ranked them in order of preference. The results indicated that the yeast strains varied significantly in terms of their capabilities to (i) produce volatile thiols and fermentation metabolites; and (ii) to modulate the varietal characters of Sauvignon Blanc wine. Yeast strains that produced the highest levels of volatile thiols were responsible for wines with the highest perceived intensity of fruitiness, and these wines were preferred by the tasting panels. While the ‘green’ characters in Sauvignon Blanc wines can be manipulated through vineyard management, the ‘tropical fruity’ characters appear to be largely dependent on the wine yeast strain used during fermentation. Therefore, the choice of yeast strain offers great potential to modulate wine aroma profiles to definable styles and predetermined consumer market specifications.     

不同产区赤霞珠葡萄酒酚类物质特征性分析

目的 探究赤霞珠葡萄酒酚类物质的产区差异性。方法 利用高效液相色谱,分析了新疆天山北麓产区、焉耆盆地产区与山东半岛产区赤霞珠葡萄酒中酚类物质组成与含量,结合多元统计方法进行评价。结果 新疆天山北麓产区、焉耆盆地产区与山东半岛产区赤霞珠葡萄酒的酚类物质含量差异较大,其中新疆两产区的原花青素B1、儿茶素、表儿茶素、对香豆酸、总黄烷醇类、总黄酮醇类、总类黄酮及总酚含量显着高于山东半岛产区(P<0.05),焉耆盆地产区芦丁、槲皮苷、白藜芦醇含量显着高于山东半岛产区(P<0.05)。基于酚类物质的聚类分析结果显示,当欧氏距离超过15时,山东半岛产区样品聚为一类,新疆两个产区葡萄酒样品聚在一起;基于酚类物质的Fisher判别分析能区分山东半岛产区样品,对新疆两个产区个别样品有误判,回代检验与交叉验证合计正确率分别为91.30%和86.96%。结论 新疆天山北麓、焉耆盆地与山东半岛产区赤霞珠葡萄酒酚类物质具有明显的产地差异性。     

发酵后混酿调控‘赤霞珠’葡萄酒的香气和色泽

本研究以单品种‘赤霞珠’葡萄酒为主体,‘品丽珠’、‘马瑟兰’和‘小味儿多’葡萄酒分别为配体以10%、20%、30%三种比例进行发酵后二元混酿,旨在通过不同风格葡萄酒间不同比例的混和,弥补单一品种葡萄酒的缺陷和提升风味品质。通过气相色谱-质谱联用(GC-MS)和高效液相色谱-三重串联四极杆质谱(HPLC-Qq Q-MS/MS)测定葡萄酒中风味物质,结合感官定量描述(QDA)和CIELAB检测体系对香气和颜色感官品质进行分析。瓶储6个月后,仅果香酯类物质质量浓度较高的‘品丽珠’在混酿比例大于20%时显著提高了混酿组乙酸酯类物质质量浓度(p<0.05);‘马瑟兰’的比例大于10%时能显著提高类异戊二烯类物质质量浓度,有利于提高花香降低生青味,同时降低黄色色调;‘小味儿多’的混酿比例在30%时有较好效果,显著提高混酿组黄烷醇(1.43倍)、黄酮醇(1.27倍)、酚酸(4.68倍)质量浓度有利于颜色稳定。因此可通过发酵后混酿调控‘赤霞珠’葡萄酒香气和颜色品质,为科学制定混酿方案提供理论依据。     

Classification of Boal,Malvazia, Sercial and Verdelho wines based on terpenoid patterns

Thirty-six Madeira wine samples from Boal, Malvazia, Sercial and Verdelho white grape varieties were analyzed in order to estimate the free fraction of monoterpenols and C₁₃ norisoprenoids (terpenoid compounds) using dynamic headspace solid phase micro-extraction (HS-SPME) technique coupled with gas chromatography–mass spectrometry (GC–MS). The average values from three vintages (1998–2000) show that these wines have characteristic profiles of terpenoid compounds. Malvazia wines exhibits the highest values of total free monoterpenols, contrary to Verdelho wines which had the lowest levels of terpenoids but produced the highest concentration of farnesol. The use of multivariate analysis techniques allows establishing relations between the compounds and the varieties under investigation. Principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to the obtained matrix data. A good separation and classification power between the four groups as a function of their varietal origin was observed.     

Phenolic resins for can coatings: I. Phenol-based resole analysed by GC-MS, GC×GC, NPLC-GC and SEC

Phenolic resins (resoles) are used for curing expoxy and polyester coatings, e.g., for food cans. They consist of oligomeric materials prepared from phenols (phenol, cresol, tert.-butyl phenol), formaldehyde and butanol and are an analytical challenge because of the complexity of their composition. A phenol-based resole was selected for a first investigation of various analytical techniques: gas chromatography (GC)-mass spectrometry (MS), comprehensive two-dimensional GC (GC×GC), normal phase high-performance liquid chromatography (NPLC, primarily of interest for preseparation for GC analysis), and size exclusion chromatography (SEC). Mass spectra are discussed for some selected compounds and a list of spectra is added. GC×GC was the most powerful method for separating and visualizing the composition of the complex mixture, but the whole battery of methods might be needed to characterize resoles and to analyse their migration into food or food simulants.     

Characterisation of Asturian cider apples on the basis of their aromatic profile by high-speed gas chromatography and solid-phase microextraction

Headspace solid-phase microextraction (SPME) coupled to high-speed gas chromatography with FID detector (HSGC-FID) and with quadrupole mass spectrometric detector (GC–MS) was employed to study the volatile compounds in Asturian cider apples. The optimised conditions used for characterisation of cider apple were: sample equilibration at 25 °C for 12 h, followed by PDMS–DVB fibre exposure to the headspace above the sample for 5 min and finally thermal desorption of the adsorbed substances in the injector port for GC analysis. The use of high-speed gas chromatography allowed the separation of 27 compounds in less than 8 min, reducing the analysis time in 80% compared to conventional gas chromatography. A simple, rapid and reliable method to analyze volatile compounds in cider apples has been developed. The aromatic profile of 59 apple samples included in eight apple varieties was analysed. The different apples were obtained from two consecutive harvests (2005 and 2006). The apples volatile compounds together with chemometric techniques such as principal components analysis (PCA), Bayesian analysis and linear discriminant analysis (LDA), allowed us to differentiate apples on the basis of the sweet or sharp category to which the cider apple variety belongs. Volatile compounds such as ethyl heptanoate, E-farnesene, ethyl butyrate and hexyl caprylate are closely related to cider apple cultivars of the sweet category, while propyl butyrate and butyl acetate are related to the sharp class.     

Volatile Composition of Macedonian and Hungarian Wines Assessed by GC/MS

The volatile composition of eight varietal wines Vranec, Merlot, Cabernet Sauvignon, Temjanika and Chardonnay from the Republic of Macedonia, and Portugieser, Kékfrankos and Tokaji Aszú from Hungary has been characterized by means of gas chromatography/mass spectrometry technique. The wine volatile compounds were extracted in dichloromethane, and the extracts were concentrated under nitrogen. Forty-four volatile compounds have been identified mainly using the NIST mass spectral library and by comparison with the available standards used for quantification as well. Differences between the wines were noted for a number of compounds, such as a higher concentration of 1-pentanol and 2-phenyl ethanol in the red wines. Monoterpenes, linalool and terpineol were detected only in the white wines, Chardonnay and Tokaji. Macedonian red wines were characterized by a higher level of alcohols, while the Hungarian wines contained a higher amount of esters, fatty acids and lactones. A statistical treatment including one-way ANOVA, followed by a Tukey’s test has been performed in order to ascertain possible significant differences between the wines studied, and principal component analysis to study the possible grouping of the wines.     

应用香气化合物多维统计分析方法建立赤霞珠葡萄酒原产地模型

以烟台、新疆、宁夏与北京四大产区32款赤霞珠葡萄酒作为实验样本,采用搅拌棒吸附萃取(SBSE)与气相色谱-质谱联(GC-MS)、液液微萃取技术(LLME)与气相色谱-质谱联用(GC-MS)定量分析了葡萄酒中59种挥发性香气成分。定量数据运用多维统计方法进行分析,通过方差分析(ANOVA)与主成分分析(PCA)选出13种代表性化合物作为葡萄酒产地判别的自变量(4-萜品醇、1-壬醇、2-苯乙醇、乙酸2-苯乙酯、3-甲硫基-1-丙醇、苯甲酸、4-甲基苯酚、α-萜品醇、癸酸、辛酸乙酯、3-辛醇、2-壬醇、棕榈酸乙酯),用这13种物质进行判别分析(DA)并建立了赤霞珠葡萄酒的原产地鉴定模型。该模型对32款不同产区的葡萄酒进行了正确的分类,交叉验证的结果显示,对未知样品归类的准确率到达100%,充分肯定了此模型对赤霞珠葡萄酒原产地鉴别的能力。     

Volatile profile and differentiation between Albariño wines from different origins

Commercial Albariño wines from different subzones of Certified Brand of Origin ‘Rías Baixas’ (NW Spain) were analysed over four consecutive harvests. The contents of monoterpenes, volatile phenols, alcohols, sulphur compounds, acetates, fatty acids and ethyl esters were determined by gas chromatography (flame ionisation detector and flame photometric detector) and gas chromatography–mass spectrometry. These white wines presented high concentrations of free monoterpenes, volatile phenols, acetates, and ethyl esters, while the levels of sulphur compounds, known as default compounds, were very low. All the wines were elaborated from Albariño grapes, but they were produced by different enological practices, such as skin contact and by carrying out malolactic fermentation or not. No significant differences were found between wines from the same subzone and from different vintages. The results obtained, and confirmed by Principal component and linear discriminant analysis, showed a differentiation among these wines as a function of the Galician subzone of origin.     

Enhancement of volatile aromatic compounds in black raspberry wines via enzymatic treatment

Robus coreanus Miquel is widely used in the production of Korean black raspberry (KBR) wine owing to its health benefits and commercial value. The effects of three different commercially available glycosidase enzymes on the volatile compounds in KBR wines were investigated with large‐scale fermentation to develop a high‐flavour‐quality wine. Volatile aroma compounds from the wines were analysed using headspace‐solid phase micro‐extraction‐gas chromatography–mass spectrometry (HS‐SPME‐GC–MS) and sensory evaluations were performed to evaluate the flavour characteristics. KBR wines treated with commercial enzymes yielded high concentrations of terpenes and esters compared with the control wine because the odourless non‐volatile glycosides in KBR wines were converted to their corresponding free forms by the enzymes. HS‐SPME‐GC–MS‐SIM analysis showed that the primary monoterpene compounds in KBR wines treated by the enzymes were myrtenol, linalool, citronellol and a significant quantity of compounds such as 2‐phenyl ethanol and ethyl benzoate, which contributed to the flavour of KBR wine, as determined by GC‐FID. KBR wines treated with the enzymes exhibited different sensory characteristics from the control wine owing to higher intensity of floral and fruity aromas. KBR wine treated with CYTOLASE PCL5 on a large scale exhibited the highest sensory preference. Copyright © 2017 The Institute of Brewing & Distilling     

黑果腺肋花楸与赤霞珠波特酒中挥发性香气成分分析

以黑果腺肋花楸和赤霞珠葡萄为原料,在二者混合发酵过程中添加无核白、霞多丽、赤霞珠3种葡萄蒸馏酒终止酒精发酵,制备波特酒。采用顶空固相微萃取（HS-SPME）结合全二维气相色谱-飞行时间质谱（GC×GC-TOF MS）技术,对黑果腺肋花楸和赤霞珠波特酒的挥发性香气成分进行分析,并对结果进行主成分分析（PCA）。结果表明,3种波特酒中共检测出68种挥发性香气成分,包括酯类25种、醇类21种、酸类7种、酮类6种、醛类4种、其他类5种。对3种波特酒的共有挥发性物质和挥发性化合物进行主成分分析,发现醇类和醛类物质是影响波特酒香气的主要因素。香气品质评价模型结果表明,添加赤霞珠蒸馏酒的波特酒香气品质最佳,添加霞多丽蒸馏酒的波特酒次之,添加无核白蒸馏酒的波特酒最差。     

黑果腺肋花楸酒与赤霞珠葡萄酒香气物质对比分析

以赤霞珠葡萄酒为参照分析黑果腺肋花楸发酵酒的香气物质组成并进行感官品评,评价其酿酒潜质,为开发适宜消费者口味的黑果腺肋花楸酒提供参考。采用顶空固相微萃取结合气相色谱-质谱分析酒的香气物质成分。结果显示：黑果腺肋花楸酒香气物质含量为赤霞珠葡萄酒的2.73 倍,香气物质种类分别为41 种和40 种,其中共有的18 种。醇类物质含量最高,分别占总香气的62.11%和73.87%。依据香气活度值,酯类物质对酒的香气贡献最大,分别为36.57%和22.04%。黑果腺肋花楸酒的主体香气物质是大马士酮、辛酸乙酯、正己酸乙酯和乙酸异戊酯,而赤霞珠葡萄酒则为α-紫罗酮、辛酸乙酯、正己酸乙酯和苯乙醛。2 款酒中共有香气物质对香气贡献占比分别为34.20%和21.81%,说明具有一定的相似性,而大马士酮和α-紫罗酮对酒香气值的贡献分别为63.22%和76.36%,形成了各自酒的特色。经感官品评,黑果腺肋花楸酒比赤霞珠葡萄酒总得分高2 分,黑果腺肋花楸作为黑色浆果具有开发酿酒的价值。     

Chemometric investigation of the volatile content of young South African wines

The content of major volatiles of 334 wines of six different cultivars (Sauvignon Blanc, Chardonnay, Pinotage, Shiraz, Cabernet Sauvignon and Merlot) and vintage 2005 was used to investigate the aroma content of young South African wines. Wines were sourced from six different regions and various producers. Thirty-nine volatile components partially responsible for the flavour of wine were quantified. In order to investigate possible correlation between volatile content and grape variety and/or geographical origin, analysis of variance, factor analysis (FA), principal component analysis (PCA) and linear discriminant analysis (LDA) were used. Significant differences in the levels of certain volatiles were observed as a function of region and cultivar, with the latter factor proving to be more influential. A few volatile compounds were identified as potential predictors of the white wine cultivars. Prediction for red wine cultivars was poor, with the exception of Pinotage wines, for which three compounds (isoamyl acetate, isoamyl alcohol and ethyl octanoate) were identified as accurate predictors. The reasons for the importance of these three volatile compounds in distinguishing young Pinotage wines are discussed, and possible reasons for the unique levels in wines of this cultivar are highlighted.     

The detection of α‐dicarbonyl compounds in wine by formation of quinoxaline derivatives

A method to determine the most abundant α‐dicarbonyl compounds in wine was developed by reaction with 2,3‐diaminobenzene. Products such as quinoxaline derivatives were detected by high‐performance liquid chromatography (HPLC) or by gas chromatography with a mass‐selective detector (GC–MS) or a thermoionic detector (GC–NPD). HPLC and detection with a spectrophotometer (313 nm) were used for routine quantitative analysis of wines. The method is sensitive, linear and has good repeatability. Diacetyl, pentane‐2,3‐dione, glyoxal and methylglyoxal were quantified in a single run; these compounds are always encountered in wines, but levels vary with different types of wine and also during fermentation and maturation processes. A new dicarbonyl compound, phenylglyoxal, was found in wine. The evolution of dicarbonyl compounds during fermentation is reported in this paper. © 2000 Society of Chemical Industry