Effect of Pulsed Electric Field treatment on the anthocyanin composition of Grenache wines obtained with different maceration times and aging in oak barrels

MARCOS MAZA; JUAN MANUEL MARTINEZ; JAVIER RASO; IGNACIO ALVAREZ

Workshop; IFT-EFFoST 2018 International Nonthermal; 2018

Anthocyanin compounds play a very important role in the color of wine. These compounds are very unstable when wine is conserved during long time. The stability depends of oenological practices and the composition of wine. The most important factor affecting the content of these compounds in wine is the winemaking process technology and their transformation during the wine aging process. The effect of pulsed electric field (PEF) on the improvement of the extraction of polyphenols during maceration-fermentation step of red winemaking has been extensively investigated. However, the evolution of the anthocyanins obtained from grapes treated by PEF during aging in oak barrel and bottle preservation has been scarcely investigated. The objective of this research was to compare the evolution of anthocyanins during oak barrel aging of Grenache wines obtained from untreated and PEF treated grapes. PEF treatments were conducted at a flow of 2.5T/h. Six tons of grapes were treated at 4 kV/cm and 9 kJ/kg applying 370 µs-square wave pulses. Maceration time for both control and PEF wines were 3 and 6 days. Evolution of anthocyanin content (AC), total polyphenols (TPI) and color intensity (CI) was similar for the control and PEF wines. While the TPI and CI were kept constant after 6 months of aging, the AC decreased. After 6 months of aging in oak barrel the AC, TPI and CI of the PEF wine obtained with 3 maceration days were similar to those for the control wine obtained with 6 maceration days. The HPLC anthocyanic profiles of wines obtained from PEF-treated after 6 months in oak barrels were similar to those of control wine indicating that the permeabilization of the cell membranes of pomace did not produce a selective effect on any anthocyanin. Malvidin-3-glucoside and Delphinidin-3-glucoside acetate were the predominant anthocyanins in both control and PEF wines. According to the results, the application of a PEF treatment permitted to reduce the maceration time from 6 to 3 days without affecting the anthocyanic profile and content of Grenache wines after 6 month aging.