Primi risultati della utilizzazione del legname di Quercus pubescens Willd. (roverella) per la produzione di botti da invecchiamento

Abstract

Quercus pubescens Willd. (Pubescent oak or downy oak), a semi-deciduous oak, widespread in western, central and south-eastern Europe (Jalas & Suominen, 1999) is characterized by a high morphological variability (Schwarz, 1993). It grows in thermophilous broad-leaved forests, with optimum in the sub-Mediterranean belt, and is well adapted in growing in different types of soils. Thanks to its drought resistance, probably linked to the fact that it easily hybridizes with other species of Quercus genus (Ferrari & Medici, 2003), it is commonly used in reforestation. In the past, the downy oak wood was mainly used for railway thanks to its good durability properties, while nowadays it is used as firewood, occasionally for carpentry or boat construction. Recently its use has been revalued and addressed to the production of aging barrels for the production of high quality wines. Usually for aging oak barrels are used; they are made with French oak ( Quercus petraea [Matt.] Liebl.) a wood species widespread in France but also in Eastern Europe and in some areas of Asia Minor and Morocco. Its wood gives color stability, spontaneous clarification and a complex and structured aroma to wine. In an experimentation undertaken by our research team two samples of the same red wine (Aglianico made by Cantine del Notaio, in Rionero in Vulture), aged for twelve months respectively in barrels of downy oak and of French oak, were compared to evaluate chemical and sensorial differences. The comparison also involved the study of the anatomical structure of wood, and the type of drying of the staves, since the speed and type of aging can be influenced by these. It is actually important to activate reactions between wine and the surrounding environment that are responsible of the wine color, aroma and taste. Oxidation, in particular, stabilizes wine allowing it to resist longer over time, while the release of tannins permits taste harmonization. By precision analytical instrumentation it was possible to quantify the content of resveratrol and tannins, also evaluating the antioxidant power of the two tested wines. In order to evaluate consumer’s acceptance and expectations in relation to the specific perceptible profile of the product, a sensory testing of aged wines was carried out, in addition to the chemical-physical analyses. Instrumental analysis of a food can actually assure the compliance with the hygienic-sanitary and physic-chemical parameters required by the legislation, but it does not provide data on its pleasantness to the palate or on the emotion induced by scent and aromas. The sensory experience was carried out not only on two wines but also on a blended wine obtained by mixing in a 1:1 ratio the two samples. The chemical analysis showed a higher content of resveratrol and lower of tannins in the wine aged in the downy oak cask, whereas the sensory analysis showed a greater liking of the blend. It is evident that new perspectives of exploitation of downy oak wood can be opened, which could allow the production of high quality wine, also from a nutraceutical point of view, with the consequent valorization of the currently underestimated stands of this specie