Comparison of the free radical-scavenging activity in infected oidium and sound dolcetto grape cultivar grown in a terroir of Central Italy

The importance of polyphenols, which are present in many vegetables and grapes too, is well-know and documented. Specific research works about the red grape and its derivative juices and wines show that the antioxidant and/or antiradical activities are directly correlated with the complex polyphenol matrix. The content of polyphenols in grapes is clearly affected by agroecological factors: the cultivar, climatic condition, the effect of geographic origin of grapes, soil, chemistry, fertilization, and the degree of maturation. Aim of this work was value the radical-scavenging activity of polyphenols extract from skins and seeds of Dolcetto cultivar derived from infected Oidium grape and from the same sound grape. Infested Dolcetto grapes and sound Dolcetto grapes were grown in same terroir and with same training system (cordon spur).
The antiradical activity was determined by assay of free radical– 2,2 Diphenyl-1-picryl-hydrazyl (DPPH) method and total polyphenols content was determined by Folin – Ciocalteu method. Data show significant increase of total polyphenols both in skins and seeds from infected Oidium Dolcetto grape with respect to skin and seed total polyphenols from sound grape. To the contrary antioxidant activity calculated as value of ARP (1/EC50 P/D) in infected grape decreased significantly respecting sound grape. Therefore a possible relationship between the change composition of polyphenols in infected grapes and antioxidant property is suggested. While the antioxidant activity, calculated as micromoles of Trolox/g sample, increase in skins and seeds from infested Oidium grape with respect to skins e seeds from sound grape.