http://orcid.org/0000-0003-1824-2051
ABSTRACT
The aim of the study was to investigate whether the wines produced in France, Italy, Spain, and Poland differ in composition of volatile compounds, and whether red wines from Poland can be distinguished from those of other European countries. Thirty-five aroma compounds belonging to several groups – 13 alcohols, 9 acids, 3 aldehydes, 7 esters, 2 ketones, and 1 volatile phenol – were identified in the examined wines. The proportions of volatile compounds in wines from the four selected countries were similar. Statistical analysis revealed significant differences between French, Italian, Spanish, and Polish wines for 3-methylbutan-1-ol, butane-2,3-diol, phenylmethanol, 2-phenylethanol, dodecan-1-ol, propane-1,2,3-triol, diethyl butanedioate, 3-hydroxybutan-2-one, and 4-ethylphenol. In addition, diethyl butanedioate distinguished Polish wines from the other wines. Hierarchical cluster analysis (HCA) showed that the Polish wines were well separated from the other wines.
Introduction
Consumers around the world gladly drink wine because of its health benefits. Italy, France, and Spain, countries of the European Union, are the largest producers of wine in the world. According to the International Organization of Vine and Wine (OIV) in 2013 areas under vines in Spain, France, and Italy covered 1021, 793, and 705 kha, respectively. That year wine production amounted to 54.0 Mhl in Italy, 45.3 Mhl in Spain, and 42.1 Mhl in France.[Citation1] In contrast, Poland is a marginal country in the world production of wine. According to the Agricultural Market Agency, in Poland in 2012–2013 (from August 1 to July 1), the vines cultivated area amounted to a total of 97.9 ha and the production volume of wine was 898.3 hl.[Citation2]
In 2005, Poland has been classified as a country of wine potential. Wine produced in Poland can be sold in the EU market.[Citation3] Nowadays, the production of wines in Poland is low due to the cold climate, but it will probably increase. In recent years there has been increased interest in grapevines and winemaking in Poland. Farmers have seen that they can grow grape varieties that are adapted to the cold climate and produce wine from them.[Citation4,Citation5] Several winemaking regions can be distinguished in Poland, mainly in the western and southeastern parts of Poland: the area of Zielona Gora (Lubuskie Province), Lower Silesia, the vicinity of Krakow, the areas of Jaslo and Krosno (Podkarpackie Province), and along the Vistula gorge (from Sandomierz to Pulawy). Polish wines are an interesting supplement of the world wine market.[Citation5] They have a unique character and high quality, which results from traditional methods of production and production on a small scale.[Citation6] The high price of Polish wines, which is due to a high cost of production and their status as a niche product, may cause falsification.
Aroma compounds belong to several chemical classes, such as hydrocarbons, alcohols, terpenes, esters, aldehydes, ketones, acids, ethers, lactones, sulfur, and nitrogen compounds. There are hundreds of volatile compounds in wines.[Citation7] Aroma formation is influenced by several factors: grape (variety, ripeness), terroir (soil, climate), cultivation, winemaking process, and aging.[Citation8–Citation10] Identification of wine aroma components may be a useful tool in differentiating the wines from different varieties, establishing the criteria of quality and authenticity, preventing fraud, and guaranteeing their geographical origin.[Citation11]
Volatile compounds were determined by gas chromatography coupled with mass spectrometry (GC-MS).[Citation12,Citation13] Due to the complexity and low levels of aroma compounds, the use of extraction/concentration techniques is necessary before analysis.[Citation14] The most commonly used techniques for the extraction of volatile compounds in wine are: liquid–liquid extraction (LLE), solid-phase extraction (SPE), and solid-phase microextraction (SPME). LLE and SPE are laborious, time consuming, and carry the risk of contamination or losses. Compared to LLE, smaller amounts of organic solvents are used in SPE.[Citation15] SPME has many advantages: it is inexpensive, fast, simple, solvent-free, and requires little manipulation of samples.[Citation16]
The fibers used for the extraction of volatile compounds by the SPME technique can be coated with different stationary phases: divinylbenzene-carboxen-polydimethylosiloxane (DVB/CAR/PDMS), polydimethylosiloxane-divinylbenzene (PDMS/DVB), carboxen-polydimethylosiloxane (CAR/PDMS), polydimethylosiloxane (PDMS), polyacrylate (PA), and polyethyleneglikol (PEG). The main criteria for fiber selection were chromatographic peak areas and the number of peaks of the target compounds. Among these fibers, not many authors choose PA fiber for their researches. PA fiber had high extraction efficiency for most of the terpenoids under study.[Citation17] Among the other fibers, PA coating showed the lowest sorption capacity, although it extracted a larger number of volatile and semi-volatile compounds. In addition, higher alcohols and fatty acids had a higher affinity for the PA fiber.[Citation15] PA fiber showed low extraction efficiency of heterocyclic compounds such as furans, thiophenes, thiazols, and pyrazines.[Citation16] In another study, PA fiber has been previously reported as effective for the extraction of terpenes, alcohols, and norisoprenoids.[Citation14] The most suitable fiber for extraction in HS sampling in terms of the sum of the weighted chromatographic peak areas was PA.[Citation18]
In the literature, there are many publications on the determination of volatile compounds in wines originating from one country (one or more regions) and produced from one[Citation19–Citation21] or more grape varieties.[Citation13,Citation22] Only two publications compare the composition of volatile compounds in red[Citation23] and white wines[Citation24] originating from various countries and produced from one grape variety. One work (parts I–III) is devoted to the determination of aroma compounds, among other parameters, in wines from different countries and grape varieties.[Citation25–Citation27] Several studies focused on the identification of volatile components in wines produced in Poland,[Citation5,Citation28,Citation29] but to our knowledge there is no comparison of Polish red wines with red wines from other countries.
Each wine-producing country has some defined “wine regions”, characterized by a rather homogeneous climate and soil characteristics, and by the presence of dominant varieties and typical wines.[Citation26] The aim of the study was to investigate whether the wines produced in four European countries (France, Italy, Spain, and Poland) differ in the composition of volatile compounds. The aim was to also determine whether Polish red wines can be distinguished from wines of other European countries, regardless of the growing region, grape variety, and winemaking techniques in the countries. This would be of great importance for the detection of Polish wine adulterations.
Materials and methods
Wine samples
The method was applied to 35 commercial red wines, originating from different countries: France (seven samples), Italy (10 samples), Spain (eight samples), and Poland (10 samples). The wines of 2008, 2009, and 2010 vintages were produced in different regions of the countries from various varieties of Vitis vinifera. Details of wines are shown in . To protect the proprietary interests, winery identities have not been reported. French, Italian, and Spanish wines had denomination of origin or were regional wines. In Poland, there were no indications of the quality of wines of 2008, 2009, and 2010 vintages.
Table 1. Description of wine samples.
Chemicals
All chemicals were of analytical grade. Sodium chloride and hydrochloric acid were purchased from POCh Company (Gliwice, Poland). Sodium chloride was oven dried at 200°C overnight before use. Hydrochloric acid was previously dissolved in water at a concentration of 78 g/L. The internal standard, 4-hydroxy-4-methyl-2-pentanone, was obtained from Sigma-Aldrich Company (Poznan, Poland). The internal standard was previously prepared in water at a concentration of 7 mg/L. A mixture of n-alkanes (C7-C30) for the linear retention indices (LTPRI) calculations was supplied by Supelco (Bellefonte, PA, USA).
HS-SPME
A fiber holder and an 85 µm PA fiber were used (Supelco, Bellefonte, PA, USA). PA fiber was preconditioned according to the manufacturer’s instructions. The SPME conditions were optimized. In a glass vial of 7 mL, 0.9 g of NaCl, 3 mL of wine, 50 µL of HCl, 100 µL of 4-hydroxy-4-methyl-2-pentanone (as internal standard), and a magnetic stirring bar were placed. The vial was tightly capped with a polytetrafluoroethylene (PTFE)-silicone septum (Supelco, Bellefonte, PA, USA). The wine sample was incubated at 29°C for 10 min under continuous stirring at 400 rpm prior to extraction. Therefore, the fiber was exposed to the headspace (HS) at 29°C for 30 min under continuous stirring. All wines were extracted in triplicate. After extraction, the fiber was removed from the vial and thermally desorbed in the GC injection port for 2 min at 200°C, in split-less mode. Prior to each analysis, the fiber was cleaned by inserting into the auxiliary GC injection port at 280°C for 5 min. All wines were injected three times using one injection per vial and in further analysis the mean values of each volatiles compound were used.
GC/MS
The samples were analyzed using a GCMS-QP2010 gas chromatograph coupled to a quadrupole mass spectrometer (Shimadzu, Kyoto, Japan). Chromatographic separations were carried out using a CP-WAX 57CB capillary column with the following characteristics: 25 m, 0.32 mm ID × 0.2 µm film thickness, 100% polyethylene glycol (Agilent, Santa Clara, CA, USA). The carrier gas was helium at a flow rate of 1.8 mL/min. The column oven temperature program was: initial temperature 38°C for 6 min, 38–102°C at a rate of 3°C/min, 102–200°C at a rate of 7°C/min and held for 3 min, and 200–210°C at a rate of 6°C/min and held for 1 min. The total run time was 47 min. An electron ionization source was used, with a source temperature of 200°C and an electron energy of 70 eV. Mass spectral data were collected over the range of 30–300 m/z in the full scan mode (scan time 0.4 s). Data were acquired using the GCMSsolution software ver. 2. The identification of volatile compounds was achieved on the basis of their mass spectra and linear retention index. Mass spectrometric information of each chromatographic peak was compared to the NIST 05 mass spectral library, considering a minimum similarity value of 80%. A mixture of n-alkanes (C7-C30) diluted in hexane (Supelco, Bellefonte, PA, USA) was loaded onto the SPME fiber and injected under the temperature program mentioned earlier to calculate the LTPRI of each extracted compound. Experimental LTPRI were compared to the retention indices reported in the literature for similar chromatographic columns. Semiquantitative data of the aroma compounds were calculated by relating the peak area of volatiles to the peak area of the internal standard. The concentrations of volatiles were expressed as µg/L.
Statistical analysis
Data analysis was conducted using the Statistica 10.0 software package (StatSoft, Krakow, Poland). One-way analysis of variance (ANOVA) was applied to test whether there were any statistically significant differences between French, Italian, Spanish, and Polish wines considering each volatile compound. Nonparametric Kruskal–Wallis test was applied for the compounds, for which the assumptions of variance analysis were not fulfilled. Multiple comparisons were made to determine in which countries the differences were statistically significant. Hierarchical cluster analysis (HCA) was performed to verify whether the test wines could be divided into groups when taking into account all the statistically significant compounds. The wines were grouped using the Ward distance matrix, which was formed on the basis of the Euclidean distance.
Results and discussion
PA fiber was applied in the present study. Thirty-five aroma compounds belonging to several groups – alcohols (13 compounds), acids (9 compounds), aldehydes (3 compounds), esters (7 compounds), ketones (2 compounds), and volatile phenols (1 compound, 4-ethylphenol) – were identified in French, Italian, Spanish, and Polish wines (). These volatiles were produced mainly during fermentation (secondary products). The higher alcohols could be synthesized by yeast metabolism through two mechanisms: anabolic pathway from glucose or catabolic pathway from their corresponding amino acids (e.g., leucine is transformed into 3-methylbutanol, valine into 2-methylpropanol, and phenylalanine into 2-phenylethanol). Fatty acids could be produced via anabolic pathways by yeast or during β-oxidation of long-chain fatty acids. Aldehydes are formed from unsaturated fatty acids (linoleic acid, linolenic acid) and as a result of lipoxygenase activity. Acetate esters are the products of the reaction of acetyl-CoA with higher alcohols that are formed from the degradation of amino acids or carbohydrates. Ethyl esters are produced enzymatically during yeast fermentation and from the ethanolysis of acetyl-CoA that is formed during fatty acids synthesis or degradation. The ketones are a result of a condensation of activated fatty acids. Volatile phenols (e.g. 4-ethylphenol) could be derived from hydroxycinnamic acids by decarboxylation.[Citation14,Citation20,Citation30]
Table 2 Volatile compounds identified in wines.
The relative concentrations of aroma compounds in French, Italian, Spanish, and Polish wines are, respectively, shown in – (data were presented as mean values obtained from three replicates). To verify whether the examined wines differentiated in proportions of aroma compounds classes, the sub-total concentration of particular classes and their percentage of the total content of volatile compounds were calculated. The proportions of volatile compounds in French, Italian, Spanish, and Polish wines were similar. A majority of the aroma compounds were alcohols, considering their number and concentration of identified volatiles in wines from the four selected countries. Concentrations of alcohols were 44.98–74.52% of the total volatile compounds in French wines, 51.15–66.61% in Italian wines, 46.02–57.86% in Spanish wines, and 42.85–67.73% in Polish wines. All the wines tested had average concentrations of esters and acids. The minor compounds were aldehydes, ketones, and volatile phenols. Only one volatile phenol – 4-ethylphenol – was identified. The concentrations of aldehydes ranged from “not detected” to 0.38%, 0.1–0.41%, 0.04–0.49%, and 0.02–0.45% in French, Italian, Spanish, and Polish wines, respectively; ketones – from 0.56 to 3.55%, from “not detected” to 3.50%, from “not detected” to 3.32%, and from 0.1 to 1.71%; and 4-ethylphenol – from “not detected” to 1.15%, from 0.12 to 1.72%, from “not detected” to 0.52%, and from “not detected” to 0.39%. In this study, one Italian wine was of Negroamaro variety (I_2). The wine contained 51.15% of alcohols, 30.28% of esters, 16.61% of acids, 1.61% of ketones, 0.10% of aldehydes, and 0.26% of volatile phenols. Tufariello et al.[Citation30] found similar proportions of volatile compounds in Negroamaro wines.
Table 3. Relative concentrations of volatile compounds (µg/L) in French red wines.
Table 4. Relative concentrations of volatile compounds (µg/L) in Italian red wines.
Table 5. Relative concentrations of volatile compounds (µg/L) in Spanish red wines.
Table 6. Relative concentrations of volatile compounds (µg/L) in Polish red wines.
In wines from France, the total concentration of volatile compounds ranged from 947.13 to 2535.36 µg/L (). The F_4 wine had the lowest amounts of aroma, while F_3 had the highest. The sub-total concentration of alcohols varied from 426.06 µg/L to 1889.40 µg/L, which was mainly due to the concentrations of 3-methylbutan-1-ol and 2-phenylethanol. The concentration of acids ranged from 135.98 to 301.9 µg/L. This volatile fraction was mainly composed of acetic acid. The sub-total concentration of aldehydes varied from “not detected” to 6.37 µg/L and was due to the presence of nonanal, furan-2-carbaldehyde, and decanal. In one French wine (wine F_7) these aldehydes were not found. The concentration of esters ranged from 244.46 to 465.28 µg/L. This volatile fraction was composed of six ethyl esters, mainly ethyl 2-hydroxypropanoate, ethyl octanoate, diethyl butanedioate, and one acetate ester, 3-methylbutyl acetate in the case of one French wine (wine F_2). The sub-total content of ketones varied from 8.52 to 36.04 µg/L. 3-Hydroxybutan-2-one was the most abundant compounds among two detected ketones. The content of 4-ethylphenol was from “not detected” to 19.83 µg/L. In this study, three out of seven French wines were of Merlot variety. Gamero et al.[Citation12] found some of the same aroma compounds in French wines of Merlot variety, such as (Z)-3-hexen-1-ol (cis-3-heksenol), phenylmethanol (benzyl alcohol), furfural (furan-2-carbaldehyde), and 4-ethylphenol, but did not report its concentrations. The authors focused on the sensitivity of different aroma extraction methods.
Concentrations of the total volatile compounds from Italy varied from 991.83 µg/L for wine I_8 to 3517.80 µg/L for wine I_10 (). The sub-total concentration of alcohols ranged from 638.33 to 2323.66 µg/L, for acids from 110.9 to 729.67 µg/L, for aldehydes from 1.22 to 14.25 µg/L, for esters from 205.47 to 742.19 µg/L, for ketones from “not detected” to 34.67 µg/L, and for 4-ethylphenol from 1.24 to 46.31 µg/L. The fraction of alcohols mainly composed of 3-methylbutan-1-ol and 2-phenylethanol, acids – of acetic acid, aldehydes – of nonanal, furan-2-carbaldehyde, and decanal, esters – of ethyl 2-hydroxypropanoate, ethyl octanoate, and diethyl butanedioate, and ketones – of 3-hydroxybutan-2-one. None of the ketones were found in two Italian wines (wine I_4 and I_6). In addition, octadecanoic acid and 1-hydroxypropan-2-one were not detected in any Italian wines. Tufariello et al.[Citation30] and Capone et al.[Citation35] reported that 2-methylbutan-1-ol and 3-methylbutan-1-ol, 2-phenylethanol and acetic acid were also present in higher amounts in aroma compound classes in Negroamaro and Primitivo wines. According to Sagratini et al.,[Citation19] 3-methylbutan-1-ol and 2-phenylethanol were the most abundant alcohols of Montepulciano wines from the Marches and Abruzzo regions. In this study, ethyl hexanoate was not detected in Negroamaro wine (I_2) and in Montepulciano wine from Marches (I_8), while Tufariello et al.[Citation30] and Sagratini et al.[Citation19] found that ethyl hexanoate was the dominating ester in the examined wines. 3-Methylbutyl acetate was the only acetate identified in Italian wines, which is in agreement with the results reported by Tufariello et al.[Citation30] Ethyl octanoate had higher concentrations in Montepulciano wines from Abruzzo (I_1, I_4) than in Montepulciano wine from Marches (I_8), while this compound showed similar percentages in both Marches and Abruzzo Montepulciano examined by Sagratini et al.[Citation19] Wines I_5, I_6, and I_7 of Cabernet Sauvignon from Trentino, Cabernet Sauvignon from Veneto, and Merlot from Veneto, respectively, contained 4-ethylphenol.
Wines from Spain contained between 1216.49 and 2250.67 µg/L of total volatile compounds (). The S_1 wine had the lowest amount of aroma, while S_5 had the highest. The sub-total concentration of alcohols ranged from 572.61 to 1294.71 µg/L. Among the identified alcohols, 3-methylbutan-1-ol had the highest concentrations, followed by 2-phenylethanol and butane-2,3-diol. 2-Phenoxyethanol was not detected in any Spanish wines. The concentration of acids varied from 238.15 to 589.4 µg/L. The acid found in appreciable concentrations in Spanish wines was acetic acid. The sub-total concentration of aldehydes ranged from 0.87 to 11.03 µg/L caused by nonanal, furan-2-carbaldehyde, and decanal. The concentration of esters varied from 361.38 to 607.85µg/L. Ethyl 2-hydroxypropanoate was the first abundant ester and ethyl octanoate was the second one. The sub-total content of ketones ranged from “not detected” to 54.24 µg/L. 3-Hydroxybutan-2-one showed higher levels in comparison with 1-hydroxypropan-2-one. No ketones were found in one Spanish wine (wine S_7). The content of 4-ethylphenol varied from “not detected” to 9.06 µg/L. In our examinations, most Spanish wines were of Tempranillo variety: S_1, S_3, S_4, S_5, S_7, and S_8. Similar to our studies, Vilanova et al.[Citation36] and Martínez-Pinilla et al.[Citation37] found that alcohols constituted the largest class of aroma compounds in Tempranillo wines, mainly 2-methylbutan-1-ol and 3-methylbutan-1-ol. Furthermore, ethyl 2-hydroxypropanoate (ethyl lactate) was the most abundant ethyl ester. In contrast, hexanoic acid[Citation36] and octanoic acid[Citation37] had the highest content within acids.
Concentrations of the total volatile compounds from Poland varied from 897.48 µg/L for wine P_7 to 1587.51 µg/L for wine P_1 (). The sub-total concentration of alcohols ranged from 491.29 to 1070.82 µg/L, acids – from 149.46 to 292.92 µg/L, aldehydes – from 0.28 to 5.95 µg/L, esters – from 104.83 to 505.32 µg/L, and ketones – from 1.17 to 21.37 µg/L. 4-Ethylphenol was present only in one wine (wine P_10) at a concentration of 5.32 µg/L. Polish wines were mainly characterized by a high content of 3-methylbutan-1-ol, 2-phenylethanol, and butane-2,3-diol among all identified alcohols, acetic acid among acids, ethyl 2-hydroxypropanoate and ethyl octanoate among the identified esters, and 3-hydroxybutan-2-one among the ketones. Furan-2-carbaldehyde had the highest content of all identified aldehydes in wines from Poland. In this study, most of the Polish wines were of Rondo and Regent varieties. Several authors studied the volatile components in wines produced in Poland,[Citation5,Citation28,Citation29] but they were white and red wines from other grape varieties.
One factor – country – ANOVA showed statistically significant differences among French, Italian, Spanish, and Polish wines for butane-2,3-diol and 3-hydroxybutan-2-one. The Kruskal–Wallis test revealed significant differences for the following compounds: 3-methylbutan-1-ol, phenylmethanol, 2-phenylethanol, dodecan-1-ol, propane-1,2,3-triol, diethyl butanedioate, and 4-ethylphenol. Multiple comparisons showed that French wines significantly differed from Spanish wines in terms of butane-2,3-diol contents and from Polish wines in terms of phenylmethanol, 2-phenylethanol, and diethyl butanedioate contents. Significant volatile compounds for the differentiation of Italian and Spanish wines were: butane-2,3-diol, 4-ethylphenol, and propane-1,2,3-triol, and for Italian and Polish wines: 3-methylbutan-1-ol, phenylmethanol, 2-phenylethanol, dodecan-1-ol, 4-ethylphenol, propane-1,2,3-triol, and diethyl butanedioate. Spanish wines significantly differed from Polish wines in terms of diethyl butanedioate and 3-hydroxybutan-2-one contents. Moreover, the multiple comparisons showed that diethyl butanedioate distinguished Polish wines from the other wines. Its content was significantly lower than in the wines from the other countries. It could be due to other conditions of malolactic fermentation in Polish wines, because diethyl butanedioate is produced mainly during malolactic fermentation.[Citation38] Malolactic fermentation can occur spontaneously, caused by indigenous lactic acid bacteria.[Citation39]
HCA showed that the tested wines can be divided into five groups on the basis of all the statistically significant compounds (). The first group contained two Italian wines (I_4 and I_6). The second group consisted of four Italian and two French wines (I_1, I_5, I_9, I_10, F_3, F_6). Nearly all the Polish wines (except sample no. 5) constituted the third group (P_1, P_2, P_3, P_4, P_6, P_7, P_8, P_9, P_10). The fourth group contained following wines: three Spanish wines, four Italian wines, one Polish wine and most French wines (S_4, S_6, S_7, I_2, I_3, I_7, I_8, P_5, F_2, F_4, F_5, F_7). Most of the Spanish wines and one French wine formed the fifth group (S_1, S_2, S_3, S_5, S_8, F_1). It can be seen that nine Polish wines were assigned to one group. One Polish wine (P_5) was classified into a separate group. The results showed that the Polish wines were well separated from the other wines, except for sample no. 5. Römisch et al.[Citation25] reported that the application of classification and regression trees (CART) and regularized discriminant analysis (RDA) on wine chemical parameters allowed the easy discrimination of South African wines from the East European wines, but the separation of wines among Hungary, Czech Republic, and Romania was more difficult because of the small geographical distance of these countries.
Figure 1. Dendrogram constructed with Ward’s method for wines from the four selected countries (see for peak identification).
Conclusion
Comparative characterization of the volatile profiles of French, Italian, Spanish, and Polish red wines is reported for the first time. Moreover, this is the first study on the volatile composition of Polish red wines of Rondo, Regent, Pinot noir, Rondo, and Zweigelt varieties. The aroma compounds were determined by HS-SPME-GC/MS using PA fiber, which is rarely chosen by researchers. Taking into account the number and concentration of the identified volatiles in wines from the four selected countries, alcohols were the major compounds. All the wines tested had average concentrations of acids and esters. The minor compounds were aldehydes, ketones, and volatile phenols. Statistical analysis showed significant differences between French, Italian, Spanish, and Polish wines for 3-methylbutan-1-ol, butane-2,3-diol, phenylmethanol, 2-phenylethanol, dodecan-1-ol, propane-1,2,3-triol, diethyl butanedioate, 3-hydroxybutan-2-one, and 4-ethylphenol. In addition, diethyl butanedioate distinguished Polish wines from the other ones. Its content in the Polish wines was significantly lower than in the wines from the other countries. This could be due to the different conditions of malolactic fermentation in Polish wines, because diethyl butanedioate is produced mainly during malolactic fermentation. HCA revealed that when taking into account all the statistically significant compounds, Polish wines can be distinguished from wines produced in the other European countries, regardless of the growing region, grape variety, and winemaking techniques in the countries.
References
- OIV. http://www.oiv.int/public/medias/4587/oiv-noteconjmars2016-en.pdf ( accessed Sept 4, 2016).
- Burkot, P. Rynek Wina W Polsce. Biuletyn Informacyjny ARR 2014, 2, 34–40. http://www.arr.gov.pl/data/400/biuletyn_informacyjny_arr_2_2014.pdf ( accessed Sept 4, 2016).
- Council Regulation (EC) No 2165/2005 amending Regulation (EC) No 1493/1999 on the common organisation of the market in wine. Official Journal of the European Union L 345.
- Socha, R.; Gałkowska, D.; Robak, J.; Fortuna, T.; Buksa, K. Characterization of Polish Wines Produced from the Multispecies Hybrid and Vitis vinifera L. Grapes. International Journal of Food Properties 2015, 18, 699–713.
- Tarko, T.; Duda-Chodak, A.; Sroka, P.; Satora, P.; Jurasz, E. Polish Wines: Characteristics of Cool-Climate Wines. Journal of Food Composition and Analysis 2010, 23, 463–468.
- Radziwiłko, B. Roczniki Ekonomiczne Kujawsko-Pomorskiej Szkoły Wyższej w Bydgoszczy. Determinanty Rozwoju oraz ich Wpływ na Obecny Stan Produkcji Wina Gronowego w Polsce 2012, 5, 427–440. http://kpsw.edu.pl/pobierz/wydawnictwo/re5/radziwilko.pdf ( accessed Sept 4, 2016).
- Sánchez-Palomo, E.; Gómez García-Carpintero, E.; Alonso-Villegas, R.; González Viñas, M.A. Characterization of Aroma Compounds of Verdejo White Wines from the La Mancha Region by Odour Activity Values. Flavour and Fragrance Journal 2010, 25, 456–462.
- Yildirim, H.K.; Elmaci, Y.; Ova, G.; Altuğ, T.; Yücel, U. Descriptive Analysis of Red Wines from Different Grape Cultivars in Turkey. International Journal of Food Properties 2007, 10, 93–102.
- He, Y.N.; Ning, P.F.; Yue, T.X.; Zhang, Z.W. Volatile Profiles of Cabernet Gernischet Wine under Rain-Shelter Cultivation and Open-Field Cultivation Using SPME-GC/MS. International Journal of Food Properties. doi:10.1080/10942912.2016.1174711
- Liu, N.; Qin, Y.; Song, Y.Y.; Tao, Y.S.; Sun., Y.; Liu, Y.L. Aroma Composition and Sensory Quality of Cabernet Sauvignon Wines Fermented by Indigenous Saccharomyces Cerevisiae Strains in the Eastern Base of the Helan Mountain, China. International Journal of Food Properties 2016, 19, 2417–2431.
- Stój, A. Metody Wykrywania Zafałszowań Win. Żywność Nauka Technologia Jakość 2011, 75(2), 17–26.
- Gamero, A.; Wesselink, W.; de Jong, C. Comparison of the Sensitivity of Different Aroma Extraction Techniques in Combination with Gas Chromatography-Mass Spectrometry to Detect Minor Aroma Compounds in Wine. Journal of Chromatography A 2013, 1272, 1–7.
- Urcan, D.E.; Lung, M.L.; Giacosa, S.; Torchio, F.; Ferrandino, A.; Vincenzi, S.; Río Segade, S.; Pop, N.; Rolle, L. Phenolic Substances, Flavor Compounds, and Textural Properties of Three Native Romanian Wine Grape Varieties. International Journal of Food Properties 2016, 19, 76–98.
- Noguerol-Pato, R.; González-Barreiro, C.; Cancho-Grande, B.; Simal-Gándara, J. Quantitative Determination and Characterization of the Main Odourants of Mencía Monovarietal Red Wines. Food Chemistry 2009, 117, 473–484.
- Mendes, B.; Gonçalves, J.; Câmara, J.S. Effectiveness of High-Throughput Miniaturized Sorbent- and Solid Phase Microextraction Techniques Combined with Gas Chromatography-Mass Spectrometry Analysis for a Rapid Screening of Volatile and Semi-Volatile Composition of WinesA a Comparative Study. Talanta 2012, 88, 79–94.
- Burin, V.M.; Marchand, S.; de Revel, G.; Bordignon-Luiz, M.T. Development and Validation of Method for Heterocyclic Compounds in Wine: Optimization of HS-SPME Conditions Applying a Response Surface Methodology. Talanta 2013, 117, 87–93.
- Câmara, J.S.; Alves, M.A.; Marques, J.C. Development of Headspace Solid-phase Microextraction-gas Chromatography–Mass Spectrometry Methodology for Analysis of Terpenoids in Madeira Wines. Analytica Chimica Acta 2006, 555, 191–200.
- Metafa, M.; Economou, A. Chemometrical Development and Comprehensive Validation of a Solid Phase Microextraction/Gas Chromatography-mass Spectrometry Methodology for the Determination of Important Free and Bound Primary Aromatics in Greek Wines. Journal of Chromatography A 2013, 1305, 244–258.
- Sagratini, G.; Maggi, F.; Caprioli, G.; Cristalli, G.; Ricciutelli, M.; Torregiani, E.; Vittori, S. Comparative Study of Aroma Profile and Phenolic Content of Montepulciano Monovarietal Red Wines from the Marches and Abruzzo Regions of Italy Using HS-SPME-GC-MS and HPLC-MS. Food Chemistry 2012, 132, 1592–1599.
- Ivanova Petropulos, V.; Bogeva, E.; Stafilov, T.; Stefova, M.; Siegmund, B.; Pabi, N.; Lankmayr, E. Study of the Influence of Maceration Time and Oenological Practices on the Aroma Profile of Vranec Wines. Food Chemistry 2014, 165, 506–514.
- Yue, T.X.; Chi, M.; Song, C.Z.; Liu, M.Y.; Meng, J.F.; Zhang, Z.W.; Li, M.H. Aroma Characterization of Cabernet Sauvignon Wine from the Plateau of Yunnan (China) with Different Altitudes Using SPME-GC/MS. International Journal of Food Properties 2015, 18, 1584–1596.
- Vilanova, M.; Cortés, S.; Santiago, J.L.; Martínez, C.; Fernández, E. Aromatic Compounds in Wines Produced during Fermentation: Effect of Three Red Cultivars. International Journal of Food Properties 2007, 10, 867–875.
- King, E.S.; Stoumen, M.; Buscema, F.; Hjelmeland, A.K.; Ebeler, S.E.; Heymann, H.; Boulton, R.B. Regional Sensory and Chemical Characteristics of Malbec Wines from Mendoza and California. Food Chemistry 2014, 143, 256–267.
- Green, J.A.; Parr, W.V.; Breitmeyer, J.; Valentin, D.; Sherlock, R. Sensory and Chemical Characterisation of Sauvignon Blanc Wine: Influence of Source of Origin. Food Research International 2011, 44, 2788–2797.
- Römisch, U.; Jӓger, H.; Capron, X.; Lanteri, S.; Forina, M.; Smeyers-Verbeke, J. Characterization and Determination of the Geographical Origin of Wines. Part III: Multivariate Discrimination and Classification Methods. European Food Research and Technology 2009, 230, 31–45.
- Schlesier, K.; Fauhl-Hassek, C.; Forina, M.; Cotea, V.; Kocsi, E.; Schoula, R.; Van Jaarsveld, F.; Witkowski, R. Characterisation and Determination of the Geographical Origin of Wines. Part I: Overview. European Food Research and Technology 2009, 230, 1–13.
- Smeyers-Verbeke, J.; Jäger, H.; Lanteri, S.; Brereton, P.; Jamin, E.; Fauhl-Hassek, C.; Forina, M.; Römisch, U. Characterisation and Determination of the Geographical Origin of Wines. Part II: Descriptive and Inductive Univariate Statistics. European Food Research and Technology 2009, 230, 15–19.
- Jeleń, H.H.; Majcher, M.; Dziadas, M.; Zawirska-Wojtasiak, R.; Czaczyk, K.; Wąsowicz, E. Volatile Compounds Responsible for Aroma of Jutrzenka Liquer Wine. Journal of Chromatography A 2011, 1218, 7566–7573.
- Dziadas, M.; Jeleń, H.H. Analysis of Terpenes in White Wines Using SPE-SPME GC/MS Approach. Analytica Chimica Acta 2010, 677, 43–49.
- Tufariello, M.; Capone, S.; Siciliano, P. Volatile Components of Negroamaro Red Wines Produced in Apulian Salento Area. Food Chemistry 2012, 132, 2155–2164.
- Welke, J.E.; Manfroi, V.; Zanus, M.; Lazzarotto, M.; Zini, C.A. Characterization of the Volatile Profile of Brazilian Merlot Wines through Comprehensive Two Dimensional Gas Chromatography Time-Of-Flight Mass Spectrometric Detection. Journal of Chromatography A 2012, 1226, 124–139.
- Mallouchos, A.; Loukatos, P.; Bekatorou, A.; Koutinas, A.; Komaitis, M. Ambient and Low Temperature Winemaking by Immobilized Cells on Brewer’s Spent Grains: Effect on Volatile Composition. Food Chemistry 2007, 104, 918–927.
- Duarte, W.F.; Dias, D.R.; Oliveira, J.M.; Teixeira, J.A.; De Almeida E Silva, J.B.; Schwan, R.F. Characterization of Different Fruit Wines Made from Cacao, Cupuassu, Gabiroba, Jaboticaba and Umbu. Food Science and Technology 2010, 43, 1564–1572.
- Song, S.; Tanga, Q.; Hayat, K.; Karangwa, E.; Zhang, X.; Xiao, Z. Effect of Enzymatic Hydrolysis with Subsequent Mild Thermal Oxidation of Tallow on Precursor Formation and Sensory Profiles of Beef Flavours Assessed by Partial Least Squares Regression. Meat Science 2014, 96, 1191–1200.
- Capone, S.; Tufariello, M.; Francioso, L.; Montagna, G.; Casino, F.; Leone, A.; Siciliano, P. Aroma Analysis by GC/MS and Electronic Nose Dedicated to Negroamaro and Primitivo Typical Italian Apulian Wines. Sensors and Actuators B 2013, 179, 259–269.
- Vilanova, M.; Paz Diago, M.; Genisheva, Z.; Oliveira, J.M.; Tardaguila, J. Early Leaf Removal Impact on Volatile Composition of Tempranillo Wines. Journal of the Science of Food and Agriculture 2012, 92, 935–942.
- Martínez-Pinilla, O.; Guadalupe, Z.; Ayestarán, B.; Pérez-Magariño, S.; Ortega-Heras, M. Characterization of Volatile Compounds and Olfactory Profile of Red Minority Varietal Wines from La Roja. Journal of the Science of Food and Agriculture 2013, 93, 3720–3729.
- Fiorini, D.; Caprioli, G.; Sagratini, G.; Maggi, F.; Vittori, S.; Marcantoni, E.; Ballini, R. Quantitative Profiling of Volatile and Phenolic Substances in the Wine Vernaccia Di Serrapetrona by Development of an HS-SPME-GC-FID/MS Method and HPLC-MS. Food Analytical Methods 2014, 7, 1651–1660.
- Bartowsky, E.J.; Costello, P.J.; Chambers, P.J. Emerging Trends in the Application of Malolactic Fermentation. Australian Journal of Grape and Wine Research 2015, 21, 663–669.