Enhanced Extraction of Valuable Compounds from Merlot Grapes by Pulsed Electric Field

Abstract

The objective of this investigation was to study the influence of pulsed electric field application on the fermentation process and wine characteristics. Investigations related, in particular, to the effects of pulsed electric field pre-treatment (500–700 V/cm) of the grapes with a short treatment duration (40–100 ms) on the evolution of color intensity, anthocyanins and phenolic content during the alcoholic fermentation of Merlot grapes and seven months after bottling. The kinetics of the extraction of valuable compounds during the vinification stage was established. Sensory analyses of untreated wines were compared to those of pulsed electric field treated wines. These results showed that the permeabilization of Merlot skin by application of a pulsed electric field treatment resulted in increased extraction of polyphenols and anthocyanins. Pulsed electric field of moderate intensity and short duration accelerates the flow kinetics of phenolic compounds through the cell membranes. Compared to the classical process, pulsed electric field treatment has the advantage of being a method of non-thermal selective extraction (<5°C) involving no loss of product quality. Phenolic compounds have an important role in enology owing to their contribution to the sensory properties of wine and to their participation in various phenomena during the vinification and aging processes. Tasting shows that pulsed electric field treatment contributes to the enhancement of the sensory attributes of wine. This technique seems to be an interesting alternative to current pre-fermentative techniques.