THE EFFECT OF PULSED ELECTRIC FIELD AND WINE AGING ON TOTAL PHENOL CONTENT AND COLOUR OF RED WINES

Pulsed Electric Field (PEF) is a non-thermal emerging technology that is applied as pre- treatment to the extraction of bioactive compounds from grapes in order to obtain high quality wine. In the present work, we applied PEF treatment (with different parameters) to two varieties of red grapes (Pinot Noir and Merlot) and recorded the total phenols and chromatic properties (RGB, CIE L*a*b*, CIE L*C*h*, wine colour index (CI), and wine tint (Tint)) of fresh (November 2016) and aged wines (6 months, April 2017). Our results showed that the efficiency of PEF treatment depends on the variety of grapes. The best extractivity of total phenols was obtained for Pinot Noir grapes, compared to Merlot (2.5 times, and 1.4 ti m es, respectively, compared to the untreated sample). All PEF treatments, for both Pinot Noir and Merlot wines, produce an increase in wine quality by positive higher levels of chromatic properties, wine colour properties. These properties are changing with the aging of wine, but differently for Pinot Noir and Merlot wines. Our results show the PEF treatment can be used in the winemaking process in order to increase the phenol content and consequently colour intensity in the red wine