Evolution of polyphenolic compounds in red wine obtained from Garnacha grape trated by Pulsed Electric Fields

MARCOS MAZA; JAVIER RASO; IGNACIO ALVAREZ

Congreso; Second WORLD CONGRESS on Electroporation; 2017

Phenolic compounds play a very important role in the quality of red wine. Its concentration is strongly affected by oenological techniques and practices. The application of pulsed electric field (PEF) to the grapes after destemming, increases the extraction of phenolic compounds during the maceration-fermentation stage. The effect of the PEF has been widely investigated. However, most of these studies have been performed in batch and when the treatments has been applied in continuous flow the highest electric field assayed was 4 kV/cm. The objective of this research was to evaluate the evolution of polyphenols in wine obtained from Garnacha grapes treated by PEF at electric field strength in the range of 1 to 8 kV/cm after 5 months of bottling. The PEF modulators used in this research were Modulator PG (ScandiNova, Uppsala, Sweden) for treatments of 4, 6, and 8 kV/cm and EPULSUS® PM1-10 (Energy Pulse Systems, Lisbon Portugal) for treatments of 1 and 4 KV/cm. The treatment chamber was collinear with two treatment zones of 2.5 cm of gap and 3.5 cm and of inner diameter. Processing flow was 400 kg/h. The maceration-fermentation was carried out in tanks of 100 L at 18ºC. The maceration for the control sample was 4 (CS4) and 13 (CS13) days. For samples treated with the PG modulator for 8 kV/cm (SCA8) and 6 kV/cm (SCA6) was 4 days and for samples treated at 4 kV/cm (SCA4), 1 kV/cm (EPS1) and 4 kV/cm (EPS4) was 6 days. Total polyphenols (TPI), color intensity (CI), total anthocyanins (ANT) and condensed tannins (TA) were analyzed from fermentation and up to 5 months of conservation. Significant differences were found in the wines obtained from grapes treated at 6 and 8 kV/cm with respect to the CS4 after 5 moths of bottling, but no differences were observed between treatments of 6 and 8 kV/cm. TPI, CI, TA and ANT of wines treated by PEF were 46, 72, 95 and 34% higher than the CS4 and 12, 28, 21 and 20% higher than CS13. There were no significant differences in oenological parameters between wines obtained from grapes treated at 4 kV/cm and the values of these parameters were between those obtained from grapes treated at 1 and 6 kV/cm with the two different modulators. According to the results obtained in this research, the differences observed between the wines obtained from grapes treated by PEF and the control wines at the end of the maceration were kept after 5 month of aging in bottled and confirm that a treatment of 6 kV/cm and 6 kJ/kg was the most efective in order to reduce maceration time or to improve polyphenol content in Garnacha wine