Volatile and Phenolic Composition of Monovarietal Red Wines of Valpolicella Appellations
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Received: 29 June 2020 y Accepted: 27 January 2021 y Published: 15 March 2021 DOI:10.20870/oeno-one.2021.55.1.3865 Volatile and phenolic composition of monovarietal red wines of Valpolicella appellations Davide Slaghenaufi, Enrico Peruch, Marco De Cosmi, Léa Nouvelet and Maurizio Ugliano* Department of Biotechnology, University of Verona, Italy *corresponding author: [email protected] ABSTRACT The volatile and phenolic compositions of nine monovarietal wines from the following grape varieties allowed in the Valpolicella appellation were investigated: Corvina, Corvinone, Rondinella, Molinara, Oseleta, Raboso, Croatina, Sangiovese and Cabernet-Sauvignon. Different clones were also investigated for Corvina and Corvinone, the two main varieties of the appellation. All grapes were harvested from a single experimental block and vinified following a standard protocol. Wines from different clones of Corvina were characterised by higher monoterpenols content, including linalool, α-terpineol and geraniol, as well as by a peculiar pattern of C6-alcohols. Relatively high levels of monoterpene alcohols were also found in Corvinone wines, while Oseleta showed the highest concentration of terpinen-4-ol and cis- and trans- isomers of linalool oxide. The evaluation of the wine aroma profile by means of different aromatic series indicated higher values for the “floral”, “fruity” and “ripe fruit” series for Corvina and Corvinone wines. Major differences in phenolic composition were found between the different varieties of wine. The total phenolics and total tannins values for Corvina, Corvinone, Rondinella and Molinara wines indicated relatively low phenolic content in comparison with Croatina, Oseleta, Cabernet-Sauvignon. There were also major differences in the content of individual phenolic compounds, in particular anthocyanins, between the monovarietal wines. KEYWORDS wine aroma, red wine, monoterpenols, Valpolicella OENO One 2021, 1, 279-294 © 2021 International Viticulture and Enology Society - IVES 279 Davide Slaghenaufi et al. INTRODUCTION wines (Slaghenaufi & Ugliano 2018; Slaghenaufiet al., 2019). Moreover, an evaluation of different In traditional wine producing countries, such as percentages of a combination of Corvina, Italy, France and Spain, the appellation of origin Corvinone and Rondinella has been carried out system is well-established and plays a central for the production of Amarone wine (Bellincontro role in the economic success of local wines in et al., 2016). Nevertheless, a comparative study international markets (Dorfmann, 2016). This that can set the ground for improved vinicultural system aims to convey to the consumer a message and winemaking practices within the appellation of uniqueness of individual products, which has not been carried out to date. reflects the relationship between the characteristics of a given wine and the geographical area in which The aim of this paper is to characterise the volatile it is produced. As such, appellations of origin and polyphenolic profile of different monovarietal have been considered of primary importance wines obtained from Valpolicella varieties, for the sustainable and cultural development of including different clones of Corvina and producing areas (FAO, 2018). Among the many Corvinone, in order to provide useful information specifications that define the characteristics for winemakers with view to improving the of individual appellations of origin, the grape production of Valpolicella wines. varieties used in winemaking are a major element of distinction. While many appellations restrict MATERIALS AND METHODS grape selection to one single variety, others allow 1. Reagents and materials a number of varieties, so that within certain limits producers can opt for different blends, with the aim 2-Octanol (97 %), 1-hexanol (99 %), cis-3-hexenol of optimising the final wine style. In the current (98 %), trans-3-hexenol (97 %), cis-2-hexenol context of climate change, there is great interest (95 %), vanillin (99 %), 2,6-dimethoxyphenol in revisiting the characteristics of different grape (99 %), linalool (97 %), terpinen-4-ol (≥ 95 %), varieties (Hannah et al., 2013), including the so- α-terpineol (90 %), nerol (≥ 97 %), geraniol called ‘minor’ varieties that are often limited to (98 %), linalool oxide (≥ 97 %), β-citronellol particular regions as part of specific appellations. (95 %), β-damascenone (≥ 98 %), isoamyl 2 alcohol (98 %), 1-pentanol (99 %), benzyl alcohol Valpolicella is a hilly area of about 240 km in (≥ 99 %), 2-phenylethanol ((≥ 99 %), vanillyl north-eastern Italy, which is located in the province alcohol (≥ 98 %), ethyl butanoate (99 %), ethyl of Verona between the city of Verona (south) and 3-methyl butanoate (≥ 98 %), isoamyl acetate the Lessini mountains (north). The renowned (≥ 95 %), ethyl hexanoate (≥ 95 %), n-hexyl Denomination of Controlled and Guaranteed acetate (≥ 98 %), ethyl lactate (≥ 98 %), ethyl Origin (DOCG) Amarone and Recioto are octanoate (≥ 98 %), ethyl decanoate (≥ 98 %), produced in this region, as well as Denomination furfural (≥ 99 %), benzaldehyde (≥ 99.5 %), of Controlled Origin (DOC) Valpolicella Classico hexanoic acid (≥ 99 %), octanoic acid (≥ 98 %), and Ripasso. These wines are obtained using local 3-methylbutanoic acid (99 %), α-ionone (90 %), grape varieties, mainly Corvina and Corvinone, β-ionone (96 %), methionol (≥ 98 %), α-ionol with smaller portions of other local varieties like (≥ 90 %), 1-butanol (≥ 99 %), 4-ethyl guaiacol Molinara, Rondinella, Oseleta. A maximum of (≥ 99%), 4-vinyl guaiacol (≥ 98 %), methyl 10 % of other grape varieties authorised in the vanillate (99 %) and ethyl vanillate (99 %) province of Verona can be used, with Raboso, were supplied by Sigma Aldrich (Milan, Italy). Croatina, Sangiovese and Cabernet-Sauvignon Dichloromethane (≥ 99.8 %) and methanol being most frequently used. Although Valpolicella (≥ 99.8 %) were provided by Honeywell (Seelze, wines are an example of blended wines where Germany). minor local varieties contribute to the production of wines with distinctive character and value 2. Wines (Paronetto & Dellaglio, 2011), little is known about the chemical composition of the wines obtained Grapes were harvested from one single experimental from grapes typically used in the Valpolicella plot of about 1 hectare, located in the town of San appellation. Pietro in Cariano (VR; 45.515264°, 10.908528°). Three clones of Corvina (ISV-CV 7, ISV-CV 48 There are a few available data to date with and VCR 446), four clones of Corvinone (ISV-CV regards phenolic characterisation (Nicolini 2, ISV-CV 3, ISV-CV 4 and ISV-CV 6), as well as & Mattivi, 1993; Mattivi et al., 2002) and the study Rondinella (clone VCR 38), Molinara (clone ISV- of certain grape-derived Corvina and Corvinone CV 100), Oseleta (clone VITIVER 1), Sangiovese 280 © 2021 International Viticulture and Enology Society - IVES OENO One 2021, 1, 279-294 (clone APSG5), Croatina (clone MICR 9), Raboso chromatograph coupled to a 5977B quadrupole del Piave (clone VCR 19) and Cabernet-Sauvignon mass spectrometer equipped with a Gerstel (clone FV6) were selected for the study. All MPS3 auto sampler (Mülheim/Ruhr, Germany). grapes were in healthy condition. Five kilograms Separation was performed using a DB-WAX of each grape sample were destemmed and one UI capillary column (30 m × 0.25, 0.25 μm film single pool of berries was obtained. Potassium thickness, Agilent Technologies) and helium metabisulfite (100 mg/kg) was added to 800 g as the carrier gas at 1.2 mL/min constant flow of grape berries. The berries were then hand- rate. The GC oven was programmed as follows: crushed and transferred to 1.5 L glass containers. at 40 °C for the first 3 min, then increasing to Fermentations were carried out at 22 ± 1 °C in a 230 °C at 4 °C/min, at which it was maintained for temperature-controlled room. The temperature 20 min. The transfer line was set at 200 °C. The of the liquid was measured twice a day and the mass spectrometer operated in electron ionisation weight loss monitored daily. Saccharomyces (EI) at 70 eV with an ion source temperature of cerevisiae VL3 (Laffort, Floirac, France) was 250 °C and quadrupole temperature of 150 °C. used for inoculation. The yeast was rehydrated Mass spectra were acquired in Scan mode. in 37 °C water for 20 min and was added to individual fermentation batches at a rate of 20 g/ Calibration curves were prepared for each analyte hL, as recommended by the manufacturer. The cap using seven concentration points and three was mixed twice a day by gently pushing it down replicate solutions per point in the model wine with a dedicated plunger, and fermentations were (12 % v/v ethanol, 3.5 g/L tartaric acid, pH 3.5). considered complete when no change in weight 20 μL of internal standard 2-octanol (42 mg/L in ethanol) were added to the solution. SPE was observed for two consecutive days. At the extraction and GC-MS analysis were performed end of fermentation, the wine was separated from as described above for the samples. Calibration the skins by pressing at 1.5 bar for 10 min with curves were obtained using Chemstation software a pneumatic press. Potassium metabisulfite was (Agilent Technologies, Inc.) by linear regression, added in order to reach a concentration of 25 mg/L plotting the response ratio (analyte peak area/ of free SO . The samples were then clarified by 2 internal standard peak area) against concentration centrifugation at 4500 rpm for 10 min at 5 °C and ratio (analyte added concentration/internal stored