Viticulture and oenology of Estonia. Polyphenols of wines of hybrid cultivars

Transcription

1 Viticulture and oenology of Estonia. Polyphenols of wines of hybrid cultivars Tõnu Püssa a, Priit Pedastsaar a,b, Kadri Karp b a Department of Food Hygiene, Estonian University of Life Sciences, Kreutzwaldi 58A, 51014, Tartu, Estonia b Department of Horticulture, Estonian University of Life Sciences, Tartu, Estonia INTRODUCTION The purpose of the presentation is to provide a short introduction of viticulture and oenology in Estonia, and to present the very first results obtained by comparing the chemical compositions of the wines of Vitis vinifera and hybrid grapevine cultivars. VITICULTURE AND OENOLOGY OF ESTONIA Climate Estonia is a northern country where it is still possible to grow grapes outdoors on the whole territory. Estonian summers are relatively short (mean frost-free period 130 days) and cool (mean accumulated temperatures over 10 C , absolute maximum C). Winters are unstable. There can be one year when the temperature falls below -35 C (absolute minimum 45.3 C) for several decades. At the same time, lasting thaws or quickly alternating periods of thaw and frost are more common. The mean yearly precipitation is mm. Viticulture The first records of growing grapes outdoors date from 1887, but this practice gained a wider popularity in the last decades of the 20 th century. Nowadays grapevine is a common hobby garden culture. About a hundred grape cultivars have been tested in Estonia (northern latitude o ), 12 of which are already in the list of recommended cultivars. For outdoor growing, hybrid cultivars of Vitis vinifera, V. amurensis and V.labrusca, such as 'Hasanski Sladki', 'Rondo', 'Zilga', Kuzminski Sinii', 'Sukribe', 'Yubilei Novgoroda' and 'Silva' are recommended. At Räpina School of Horticulture grapes have been grown outdoors since There are about 70 varieties in the collection now. Students of Räpina School have been exploring grape varieties since The Estonian University of Life Sciences (Eesti Maaülikool) has the first trial plantations of grapevines in different parts of Estonia since The main trial plantation at Rõhu near Tartu that is the practical base for teaching and scientific research in the field of viticulture and oenology was established in Viticulture is an integral part of Bachelor and Master studies in

2 horticulture at the Department of Horticulture of Eesti Maaülikool. By now we have already doctoral students studying in these fields. Oenology Traditionally, wines in Estonia have been fermented from fruits (apple) and berries (currants, strawberries etc). Grape wines represent a rather new purview and the scientific research is in its initial stage. For more information, please visit the internet site Grapes in Estonia POLYPHENOLS OF DIFFERENT WINES MATERIALS AND METHODS Polyphenols were identified and quantified in wines fermented from the berries of the following cultivars: Wine 1. Cabernet Sauvignon, France, Cabernet Sauvignon, Spain, Cabernet Sauvignon, Chile, Pinot Noir, Romania, Shiraz, South Africa, Merlot, South Africa, Hybridic Rondo (over 50% of V.vinifera), Estonia, Blend of hybridic Rondo, (50%), Zilga (25%) and Hasanski sladki (25%), Estonia, 2010 The polyphenolic composition of the wines was studied by reversed phase high performance liquid chromatography-tandem UV diode array-ion trap mass selective detection (rp-lc-dad- ESI-MS/MS) on an 1100 series system of Agilent Technologies (Palo Alto, USA). Under special attention were three classes of compounds with the highest antioxidant potential as well as hydroxystilbenes, famous for their specific health-promoting effects. RESULTS AND DISCUSSION Concentration of anthocyanins (diagram 1) The anthocyanin profile and content are cultivar-dependent, whereas the wines of hybrid cultivars are distinguished by a wider variety of anthocyanins, the list of which contains all the compounds determined in wines of V. amurensis including pelargonidin diglucoside [1]. Concentration of flavonols (diagram 2) The group of flavonols contains aglyconic quercetin, myricetin and kaempferol as well as their glycosides. Wines of hybrid grapes are characterized by relatively higher concentrations of flavonol glycosides. The highest content of total flavonols was established in the wines of Cabernet Sauvignon. The wine of Pinot Noir had a very low content of flavonols in any form.

3 Concentration of flavan-3-ols (diagram 3) Red wines studied contain remarkable amounts of catechin and epicatechin as well as their isomeric dimers (procyanidins), and B-type trimer isomers. The total content of these flavonoids, characterized by a high antioxidative capacity, is presented in diagram 3. For the content of flavan-3-ols, wines No. 4 (Pinot Noir) and No. 7, and No 8 (wines of hybrid grapevines) stand out. Concentration of hydroxystilbenes (diagram 4) Hydroxystilbenes are represented by cis- and trans-resveratrol, 3-O-glucoside = piceid, and 4-O - glucoside = resveratroloside, as well as traces of resveratrol dimers, and piceatannol and its glucoside. The concentration of aglyconic resveratrol was the highest in the wines of Pinot Noir (4) and Merlot (No. 6), followed by the wines of hybrid cultivars. In the wines studied, resveratrol is mostly in the form of two glucosides. The total molar concentration of resveratrols ranges from 22 to 40 μmoles/l, their highest content was established again in the wines of Merlot (6) and Pinot Noir (4). The wines of V. amurensis hybrids had an approximately equal content of hydroxystilbenes with the wines of Cabernet Sauvignon and Shiraz. These numbers are in the same order with hydroxystilbene contents in the wines published in literature [2,3]. CONCLUSION The number of the analysed red wines is too small to draw any profound conclusions. However, it is obvious that Nordic wines from hybrid berries that have similar contents of all the studied groups of polyphenols to the traditional red wines deserve serious attention as a potential source of physiologically active compounds. REFERENCES 1. Q. Zhao, C.-Q. Duan, J. Wang. (2010). Int. J. Mol. Sci. 11, G.L. La Torrre, M. Saitta, F. Vilasi, T. Pellicano, G. Dago. (2006). Food Chem. 94, L. Gambelli and G.P.Santaroni. (2004) J.Food Comp.Anal. 17, 613

4

5

6

7

8