UVC LIGHT IRRADIATION EFFECT ON GRAPE BERRIES ANTHOCYANINS AND TRANS-RESVERATROL

DE ROSAS, MARÍA INÉS; PONCE, MARÍA TERESA; MANZANO, HUMBERTO; MARTÍNEZ, LILIANA

Congreso; Reunión de las Sociedades de Biología; 2011

Anthocyanins (ANT) and trans-resveratrol (TR) are grape phenolic compounds which contribute to its nutraceutical properties, being very important for wine industry. UVC light irradiation increases these polyphenols depending on the cv. and the given conditions. The aim of this work was to identify the best treatment conditions of UVC light irradiation on harvested berries of Cabernet Sauvignon (CS), Tempranillo (T), and Malbec (M) in order to increase ANT and TR contents. Grape berries were irradiated with 240 W at 20 and 40 cm from the light source, for 30, 60 and 120 seconds. Polyphenols extracts were analyzed by HPLC. UVC irradiation modified ANT profile of the three cultivars.  The treatment for 30s at 40 cm on T increased the 3?4?5?-OH ANT over the 3?4?-OH and the methylated over the non methylated ones. These changes on the ANT profile switch berries tonality to bluish colors due to F3?5?H enzyme stimulation. Methylation confers more stability to ANT, being this appreciated to preserve color during wine aging. On CS the treatment for 120s at 40 cm decreased these ratios, leading to reddish colors and not such stability on the ANT. TR was increased by 30s 40 cm. The ratios on M were not affected.