Pulsed Light Effect in Red Grape Quality and Fermentation

Vitis vinifera (variety Tempranillo) grapes were processed by pulsed light (PL) at several treatment conditions before fermentation. The effect on grape external structure, wild microbial populations, phenol extraction and wine composition was monitored. PL treatments decreased significantly microbial loads in grapes. After treatment, the grapes were inoculated and fermented with Saccharomyces cerevisiae following fermentation during 2 weeks with skins and seeds. Temperature was set at 22 °C. PL treatments control wild microorganisms, especially yeasts, facilitating the growth and development of the yeast starter affecting wine quality. PL treatments of grapes can help to increase the shelf-life in postharvest technology but also improve fermentative purity and wine quality. PL is cheaper and easier to scale-up at winery than high hydrostatic pressure, pulsed electric fields or e-beam irradiation.