Phenolic characterization and antioxidant capacity of ten autochthonous vines grown in southern Italy / Caratterizzazione fenolica e potere antiossidante di dieci vitigni autoctoni allevati nel Sud Italia

Abstract

In plant foods are naturally present some bioactive compounds, that are compounds having or not nutritional value and with biological activity that is expressed in reducing the risk of developing many chronic diseases, therefore leading a key protective effect on our health. Within this group of compounds the antioxidants are included. The importance of antioxidants contained in food is associated with their ability to exert in vivo, in the human body, beneficial effects against chronical- degenerative diseases induced by oxidative stress and age. It has been attributed a positive role to grape polyphenols in terms of increase in endogenous antioxidant defenses, thanks to regulation of genes coding for key enzymes of antioxidant system. For the polyphenols it has also been recognized a specific action of tumor growth inhibition, linked to the modulation of enzymes involved in carcinogenesis or to the inhibition of growth factors and cell proliferation activation. After carbohydrates and acids, the phenolic compounds represent the largest group among grape constituents. The synthesis of these secondary metabolites takes place in two distinct phases of vine growth cycle: fruit set and maturation. The polyphenolic composition contributes to grapes and wine sensory properties, such as color, flavor, astringency, and determines the antioxidant capacity of the extract. These metabolites are mainly related to the variety and their content is influenced by climatic and environmental factors. Among the polyphenols, anthocyanins, hydroxicinnamiltartaric acids, flavonols, flavans, stilbene and resveratrol are of particular interest. Despite numerous studies in the vine-wine industry on polyphenols quantification and qualification, we don't know much about the environmental conditions that affect their synthesis in grapes and how they are extracted from it in wine production. Therefore, the aim of this work has been the study of antioxidant property and phenolic profile of ten autochthonous vines grown in two different areas of South Italy. By spectrophotometric analysis it has been possible to analyze quali-quantitive characteristics of such substances, while by ORAC method (Oxygen Radical Absorbance Capacity) we have measured, in vitro, the antioxidant action. The oenological potential has been evaluated, in relation to polyphenols content, of ten Vitis Vinifera varieties belonging to autochthonous vines of Basilicata, grown in espalier and tent in two areas: in the vineyard of Val d'Agri (PZ), in Basilicata, and in South-East Bari area, in Rutigliano (Ba), in Puglia. The ten varieties belonging to Southern Italy autochthonous vines include four black grapes and six white grapes. Data obtained on total polyphenols content, view of the considerable variability encountered, allow us to affirm that the polyphenolic ripening of wine grapes, thus the reaching of the maximum level, is very influenced by the “terroir”, defined as the cultivation area or environment, by season trend, by cultivation techniques and by the different vines nutritional conditions. The same holds true for the antioxidant activity of the 10 wine grapes varieties of this study, since it is closely related to the polyphenol