Bavaresco, L.

Civardi, S.

Elothmani, D.

Ferrari, F.

Gatti, M.

Zamboni, M.

English

JKI Open Journal Systems (Julius Kühn-Institut)

Vitis 50 (1), 43–44 (2011)Research NotePreliminary results on the effect of cluster thinning on stilbene concentra-tion and antioxidant capacity of Vitis vinifera L. 'Barbera' wineM. GATTI1), 3), S. CIVARDI1), M. ZAMBONI1), F. FERRARI2), D. ELOTHMANI3) and L. BAVARESCO1)1) Istituto di Frutti-Viticoltura, Università Cattolica del Sacro Cuore, Piacenza, Italy2) Istituto di Chimica Agraria ed Ambientale, Università Cattolica del Sacro Cuore, Piacenza, Italy3) Laboratoire GRAPPE, Ecole Supérieure d’Agriculture, Angers, FranceK e y   w o r d s :  'Barbera', cluster thinning, resveratrol, antioxidant activity, DPPH.Introduction: Stilbenes are low molecular weight phenolics synthesized by several plants, including grape-vine, with a constitutive or inducible origin. It has long been established that trans-resveratrol, the first to be dis-covered and the most studied compound, plays a significant antifungal role acting as a phytoalexin. Other experiments have shown its important antioxidant activity is positively involved on human health (ALARCÓN DE LA LASTRA et al. 2006), as well as a role in extending the lifespan of yeasts and other organisms by interacting with the sirtuin metabo-lism (LAMMING et al. 2004). Stilbenes are synthesized fol-lowing the activation of stilbene synthase (VEZZULLI et al. 2007) by abiotic and biotic elicitors, including main fungal diseases (JEANDET et al. 1995; BAVARESCO et al. 2008). The grape variety, the environmental conditions (BAVARESCO et al. 2007, DE ANDRES DE PRADO et al. 2007) and some cultural practices affect grape and the wine stilbene concentration, and therefore site selection and cultural practices includ-ing cluster thinning (PRAJITNA et al. 2007) can be managed in order to increase the grape and wine concentrations of these beneficial metabolites. This investigation studied the influence of cluster thinning on stilbene concentration and antioxidant activity in wines from Vitis vinifera L. 'Bar-bera'.Material and Methods: The trial was carried out in 2009 on two Vitis vinifera 'Barbera' vineyards placed at 245 and 380 m asl, in Tidone Valley (Piacenza, Northern Italy), north exposed and planted in 1990. The vines were Guyot trained (vertical shoot positioning), leaving 11 nodes/vine, vine spacing of 2.3 m between rows and 2.5 m in the row, with coupled plants, corresponding to 3,500 vines/ha. At veraison (August 3) a cluster thinning treatment (CT) was applied removing the distal clusters and keeping only one cluster per shoot, corresponding to a 50 % severity, while unthinned vines were included as control (C). Treatments were compared in a 2 blocks design. At ripening (Septem-ber 17) the main yield (grape yield per vine, buds and clus-ters number) and qualitative (soluble solids, pH, titratable acidity) variables were determined and, according to the field replicates, two 10-cluster samples (about 3 kg) each from 5 vines/block were harvested and vinified per each vineyard. Grapes were destemmed, crushed and treated with 0.1 g·L-1 of potassium metabisulfite, and stored ac-cording to the experimental design. Inoculation was made with Saccharomyces cerevisiae (Fermivin PDM®, DSM Delft, The Nederlands), hydrated in sucrose solution and, added at 0.2 g yeast/L of must. Fermentation was carried out in 2.5 L flasks at 25 °C during 13 d; cap was manually pushed down twice a day. After fermentation wines were racked and cold-stabilized at 2 °C for 30 d, bottled and stored at the same temperature. Wines were analyzed in or-der to determine its stilbene concentration (January 2010) and antioxidant activity (April 2010).S t i l b e n e s :  For each treatment, four wine sam-ples (2 per vineyard by origin) were processed in triplicate. Wine was directly injected after a 5 min centrifugation at 3500 rpm. Analyses were performed by an HPLC (Agilent HP 1100 – Waldbronn, Germany) coupled to a diode detec-tor (DAD) set at 325 nm to detect every stilbenes except cis-resveratrol which was set at 306 nm. A C18 (Supelco Supelcosil) column was adopted according to BAVARESCO et al. (2008). Commercial standard of trans-resveratrol (Sig-ma chemicals) was utilized while piceid standard was kind-ly supplied by F. MATTIVI, Fondazione Mach, S. Michele all’Adige, corresponding to a purity above 98 %. Quantita-tive analysis was performed by measuring peak areas.A n t i o x i d a n t   a c t i v i t y :  The antioxi-dant activity was determined by reduction of free radical DPPH method (BRAND-WILLIAMS et al. 1995) modified by the authors as follows. A stock solution of diluted red wine (1:25 in methanol) was stored at 4 °C for 90 min and then centrifuged (7 min at 8000 rpm) to promote a precipita-tion and a separation of pectins, respectively. Afterwards the stock solution was further diluted to obtain 5 final dilu-tions (1:25, 1:50, 1:125, 1:250, 1:500). A 150 µL of diluted wine was added to 3 mL of a 1.64 M methanolic solution of DPPH (Carlo Erba, Milano), incubated for 60 min at room temperature in the darkness and then the absorbance of the reaction solution was measured at 517 nm. For each sample, a blank containing 150 µL diluted wine and 3 mL methanol was incubated to correct the wine interference on absorbance. A control containing 150 µL methanol and 3 mL of the same DPPH solution was incubated. The percentage of inhibited DPPH was calculated as follows: %inib = 100– [(DOsample - DOblanc)/DOcontrol] * 100. A linear regression was obtained and the EC50 (the final wine dilu-tion required to inhibit 50 % of the initial DPPH in the reaction solution) was calculated based on the line equa-tion. Antioxidant capacity was reported as mmol Trolox equivalent per L of wine (TE mmol·L-1).S t a t i s t i c a l   a n a l y s i s :  Data were analyzed using analysis of variance and the least significance differ-Correspondence to: Prof. Dr. L. BAVARESCO, CRA-VIT Centro di Ricerca per la Viticoltura, V. le XXVIII Aprile 26, 31015 Conegliano (TV), Italy. E-mail: luigi.bavaresco@entecra.it 2 M. GATTI et al.ence was calculated by LSD test (α = 0.05). A SPSS 15.0 per Windows software was adopted.Results and Discussion: Cluster thinning applied at veraison reduced grape yield by 51.7 %, and titratable acidity by 9.6 %, while increasing the soluble solids and pH by 8.2 % and 2.6 %, respectively (data not reported), consistent with the literature (MAZZA et al. 1999, REYNOLDS et al. 2007). The wines made from treated vines showed higher anthocyanin and polyphenols concentrations (Ta-ble) compared to the control, ranging from 730 mg/L (CT) to 524 mg·L-1 (C) and from 3,535 mg·L-1 (CT) to 2,698 mg·L-1 (C), respectively. Cluster thinning enhanced the trans-piceid and trans-resveratrol wine concentration over the control, as well, ranging from 0.40 mg·L-1 (CT) to 0.26 mg·L-1 (C) and from 1.41 mg·L-1 (CT) to 0.98 mg·L-1 (C), respectively (Table). The TE was higher in wines from cluster thinning treatment (10.0 mmol·L-1) than the con-trol (6.60 mmol·L-1), corresponding to a 52 % enhance-ment (Table). Wine stilbenes and antioxidant activity of thinned vines were ≈ 50 % higher than the control vines, corresponding approximately to the cluster thinning sever-ity. Results suggest that the antioxidant activity is related to the polyphenols, anthocyanins and also stilbene content in spite of their lower concentration. Our results confirm previous findings on wines from hybrids (PRAJITNA et al. 2007) even though in the present experiment a later time of thinning was applied and the grape variety belongs to Vitis vinifera. Other investigations are required to confirm these preliminary data and further studies on the gene expression level are in progress.This research is carried out by the financial support of Can-tina Sociale di Vicobarone (Piacenza, Italy)ALARCÓN DE LA LASTRA, C.; VILLEGAS, I.; RAMÓN MARTÍN, A.; 2006: Res-veratrol as an antioxidant. In: B. B. AGGARWAL, S. SHISHODIA (Eds): Reveratrol in health disease, 33-55. Taylor & Francis, Boca Raton, FL, USA.BAVARESCO, L.; PEZZUTTO, S.; GATTI, M.; MATTIVI, F.; 2007: Role of the variety and some environmental factors on grape stilbenes. Vitis 46, 57-61.BAVARESCO, L.; VEZZULLI, S.; CIVARDI, S.; GATTI, M.; BATTILANI, P.; PIETRI, A.; FERRARI F.; 2008: Effect of lime-induced chlorosis on ochratoxin-A and stilbenic phytoalexins in grapevine (V. vinifera L.) berries infected by Aspergillus carbonarius. J. Agric. Food Chem. 56, 2085-2089.BRAND-WILLIAMS, W.; CUVELIER, M. E.; BERSET, C.; 1995: Use of a free radical method to evaluate antioxidant activity. Food Sci. Technol.-Leb. 28, 25-30.DE ANDRÉS-DE PRADO, R.; YUSTE-ROJAS, M.; SORT, X.; ANDRÉS-LACUEVA, C.; TORRES, M.; LAMUELA-RAVENTÓS, R.M.; 2007: Effect of soil type on wine produced from Vitis vinifera L. cv. Grenache in commercial vineyards. J. Agric. Food Chem. 55, 779-786.JEANDET, P.; BESSIS, R.; SBAGHI, M.; MEUNIER, P.; TROLLAT, P.; 1995: Res-veratrol content of wines of different ages: relationships with fungal disease pressure in the vineyard. Am. J. Enol. Vitic. 46, 1-3.Lamming, D. W.; Wood, J. G.; Sinclair, D. A.; 2004: Small molecules that regulate lifespan: evidence for xenohormesis. Mol. Microbiol. 53, 1003-1009.MAZZA G.; FUKUMOTO L.; DELAQUIS P.; GIRARD B.; EWERT B.; 1999: An-thocyanins, phenolics, and color of Cabernet Franc, Merlot, and Pinot Noir wines from British Columbia. J. Agric. Food Chem. 47, 4009-4017.PRAJITNA, A.; DAMI, I. E.; STEINER, T. E.; FERREE, D. C.; SCHEERENS, J. C.; SCHWARTZ, S. J.; 2007: Influence of cluster thinning on phenolic com-position, resveratrol, and antioxidant capacity in Chambourcin wine. Am. J. Enol. Vitic. 58, 346-350.REYNOLDS, A. G.; SCHLOSSER, J.; SOROKOWSKY, D.; ROBERTS, R.; WILLW-ERTH, J.; DE SAVIGNY, C.; 2007: Magnitude of viticultural and enological effects. II. Relative impacts of cluster thinning and yeast strain on com-position and sensory attributes of Chardonnay Musqué. Am. J. Enol. Vitic. 58, 25-41.VEZZULLI, S.; BATTILANI, P.; BAVARESCO, L.; 2007, Stilbene-synthase gene expression after Aspergillus carbonarius infection in grapes. Am. J. Enol. Vitic. 58, 132-134.Received May 27, 2010T a b l eImpact of cluster thinning on anthocyanins, polyphenols, stilbene concentration and antioxidant activity of 'Barbera' winesTreatmentAnthocyaninsmg/LTotal Polyphenolsmg/Ltrans-Piceidmg/Ltrans-Resveratrolmg/LTrolox equivalentmmol/LCluster thinning 730 3535 0.40 1.41 10.0Control 524 2698 0.26 0.98 6.6F 11.40 22.81 15.85 63.36 6.94Significance * ** ** *** *LSD0.05170.0 487.2 0.051 0.316 3.12*,**,***, ns: Significant at p ≤ 0.05, 0.01, 0.001, or not significant, respectively. Means were separated by the LSD test.44

Preliminary results on the effect of cluster thinning on stilbene concentration and antioxidant capacity of Vitis vinifera L. 'Barbera' wine

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Preliminary results on the effect of cluster thinning on stilbene concentration and antioxidant capacity of Vitis vinifera L. 'Barbera' wine

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