Gamma irradiation as pre-fermentative method for improving wine quality

Merlot and Traminer (Vitis vinifera L.) grapes were subjected to gamma irradiation at the panoramic 60Co source at four doses (670, 1300, 2000, 2700 Gy) and wines were produced from the irradiated grapes. HPLC analysis of musts have shown a negative impact of irradiation on the amino acids content. However, Merlot wines produced from irradiated grapes demonstrated better extraction of the coloring matter. The concentrations of anthocyanins increased with the increasing absorbed irradiation dose, while flavonols and flavanols were not affected by irradiation. Irradiation with doses up to 2000 Gy increased concentrations of fruity- floral aroma compounds, especially monoterpens and C13 norisoprenoids in wines, while a maximal dose of 2700 Gy expressed more the toasty and caramel notes due to higher concentrations of furfural and furfuryl alcohols. Results obtained suggest that ionizing irradiation might be a suitable method for grape treatment since better chemical properties in wine could be achieved.