Ozone Fumigation Postharvest Treatment for the Quality of Wine Grape

High quality wine requires high quality grape. High quality grape means good aromatic properties and texture, excellent phenols panorama, and salubrity. Ozone is known as a great sanitizing agent but little is known on its effect on grape metabolism. Grape bunches of 'Sauvignon Blanc' (Vitis vinifera L.) were hand harvested at the end of day in Castello de La Sala winery, placed in perforated boxes in one single layer and then stacked in a cold room at 10 degrees C and 70% RH (relative humidity). Ozone treatment (1.5 g h(-1)) started immediately and bunches were sampled before and after treatment which lasted 4, 8, and 16 h. The control sample consisted in grape bunch treated in similar way, placed in another cold room without ozone treatment. Total phenols on dry weight (d. w.) basis increased of 10% after 8 and 16 h treatment compared to the control sample. Hydroxycinnamic acids increased 50-100% in ozone-treated sample. Even total carotenoids raised in ozone-treated sample after 16 h. Glycosilated volatiles organic compounds (VOCs) increased in ozone-treated samples while decreased in untreated one; in contrast the free VOCs, which means the perceptible aroma compounds, were higher in untreated grape. This is an important result because the grape for vinification must have many glycosilated VOCs before fermentation which are released during the process by yeasts.